[WyattsRide]

Back story:
June of 2021, I went for a long drive on a beautiful Sunday evening. Arrived at my destination parking lot and while downshifting from 3rd to 2nd, the engine stalled. Restarted engine and it barely started and ran VERY rough. A little panicked, I tried to limp home when a dreadful sound screeched from the engine bay. Stalled again. Started again and ran rough and again stalled. Would not start again. Time for "Hilly" to get a ride to my indy shop.



After my mechanic had a chance to diagnose, he said the dreaded "Timing belt jumped a few teeth". He did a compression test on the cylinders. Here were the results. Valve damage?!?



After consulting all my 928 gurus and wizards, I was convinced to pull the engine myself (with help) and repair Hilly back to her former glory.

After months of my procrastination and then me finally committing to the work, Ed (linderpat) and I got the lump out.
Along with Ed, a ton of Thanks also goes Stan for guiding me (and Ed) through the removal process with calls, texts and Face Timing. Also, Thanks to Sean R, Pete K, Patrick, Thom, Roger and Joel for all their advice and to my other local guys Bill, Mike, Rick S and CJ for their help on the day we pulled the engine out. I've had a lot of help and support!!





To be continued......

[WyattsRide]

After the engine was out, we removed all the "accoutrements" (Wayne from NY's favorite word) and cleaning needed to be done.



Took off the Cam Covers. The spacer bolts were a problem. Even with penetrating liquids and heat, I still snapped off several of these bolts in the head. I think about 6. Looks like bolt thread extractions are in my future.

Are these spacer bolts still available? I'm hearing that they are not. If not, I would think all new Cam Cover bolts will be required. The original ones screw into these spacer bolts.



Here's my Cam Gears. I'm told they need replaced.
Right side


Left side



To be continued......

[worf]

Are you posting this on RL too?

[WyattsRide]

Are you posting this on RL too?

Not all of this. Maybe certain parts and questions. A lot of who I trust for answers are already here. I'm not really interested in a thousand opinions and comments.

[worf]

Are you posting this on RL too?

Not all of this. Maybe certain parts and questions. A lot of who I trust for answers are already here. I'm not really interested in a thousand opinions and comments.

Fair'nough. I ask because I don't want to have to keep two threads on two forums in my head so as to post something both coherent and non-repetitive.

The first issue that I see is that, apparently, you didn't set the crank to 45° BTDC before you removed the timing belt. Your crank looks like it's at 60° BTDC. *Maybe* you can very carefully turn it to 45° without 'touching' anything.

With the crank where it is right now, you can't turn the cam gears without the risk of more valve contact. And taking out the cams is more challenging/risky if you can't turn them.

From the looks of the motor as it came out, it was pretty close to TDC - at least by looking at the rotors. And both sides were pretty close to each other.

The last picture looks like the cam gears have 'jumped' counter-clockwise. So, without the crank at 45° valves may be in contact with pistons right now.

Jumping back, you have to have 'skipped' a lot of teeth for that to be the root cause. "A lot" is 4 or 5 minimum.

Now, maybe I'm reading to much into the pictures and making poor assumptions based upon them.

However, the procedure for taking out the cams without causing further damage will be somewhat different depending upon if you can safely rotate them or not.

With respect to the cam gears, yes, it looks like the left-side (driver) is done and the right side is "looking forward" to being done.

On the subject of the cam cover spacers.... those were just a bad idea to start with. I'm pretty sure some S3 folks have "deleted" those and used S4 bolts and "other stuff." However, at this point, I'm at the edge of my '928 map' as it does not extend too far into the specifics of S3 territory. @PorKen would be my first contact on the specifics of 'upgrading' those to something better.

Perhaps he'll jump in.

[WyattsRide]

duplicate post

[Crumpler]

Subscribed!

Following with interest.

[WyattsRide]

duplicate post

[WyattsRide]

Thanks WORF but I'm even further on my head removal than I have posted. This may be a problem. I don't know.

Just to be more clear. My indy mechanic reset the timing before all of the engine removal started. The engine was running but not well. He stated the timing was off 5 to 6 teeth when he got it and the tensioner was defective which was the reason for the loose belt. I'm not faulting the Poken Tensioner. I take the blame for not replacing the tensioner when I replaced the belt over 4 years ago. The Tensioner was 8 years old at that time.

Heads are removed.

Right side. Looks to us that the gasket was in great shape and no corrosion around the seal. The cylinders are all in perfect shape with no scoring. Just a lot of carbon on the piston heads. Are better pictures needed to confirm?


Left side
Same as the right side as far as conditions. Are better pictures needed to confirm?


Head bolt removal was straight forward. No problems at all removing them. Can these be reused or not recommended to do?

[WyattsRide]

The first issue that I see is that, apparently, you didn't set the crank to 45° BTDC before you removed the timing belt. Your crank looks like it's at 60° BTDC. *Maybe* you can very carefully turn it to 45° without 'touching' anything.

With the crank where it is right now, you can't turn the cam gears without the risk of more valve contact. And taking out the cams is more challenging/risky if you can't turn them.

From the looks of the motor as it came out, it was pretty close to TDC - at least by looking at the rotors. And both sides were pretty close to each other.

The last picture looks like the cam gears have 'jumped' counter-clockwise. So, without the crank at 45° valves may be in contact with pistons right now.

I can't say if the crank was a 45 BTDC before the belt was removed. Some over zealous "mechanics" removed all the front end parts (cam covers, rotors, belt, WP, Balancer etc) while I was away from the garage buying a couple correct bottom engine stand bolts. I hope everything can be put back correctly before reinstalling the heads and cams.

This is a far as I am. I have not done anything with the heads yet. They are sitting on my parts shelf until I get some additional direction.

[worf]

Thanks WORF but I'm even further on my head removal than I have posted. This may be a problem. I don't know.

It is what it is. Either the cams are in four pieces and straight, or they are not.

He stated the timing was off 5 to 6 teeth when he got it

That'll probably do it.

Right side. Looks to us that the gasket was in great shape and no corrosion around the seal. The cylinders are all in perfect shape with no scoring. Just a lot of carbon on the piston heads. Are better pictures needed to confirm?

Left side
Same as the right side as far as conditions. Are better pictures needed to confirm?

A calibrated Mark I eyeball looking close up is better than pictures.

If you say that you don't see any scoring then I don't need pictures to prove it.

What I do see is "shiny" spots in the carbon for the piston relief surfaces of all the exhaust valves. My expectation - just from the 'far away' pictures - is that all the exhaust valves are bent. If indeed it was the skipping belt that caused the engine to stop, then you know you have to have some bent valves somewhere.

I trust that the crank and pistons turn nice and smooth in the short block?

One thing you can do with some make-your-own-apparatus skills is to do a leak-down test of the short block and make sure you've got consistent leak-down across all 8 holes. That will give you a good indication of if you need to go further with wrenches.

For the heads, I would like to see a picture of each head's deck surface. I might ask to zoom in on certain sections after that. You don't want any corrosion within roughly 2mm of the edge of the fire ring and any deep holes should be 'dealt' with.

On the other hand, you can't really see how bad the corrosion is until the heads are soda blasted.

On the gripping hand, if valve contact has occurred then you're probably going to "do" the heads and a light decking - minimum - is going to be part of that.

When I have a set of heads on the bench these days, they always go to "my guy" for a thorough job. It doesn't make a lot of sense to go this far and not do that on a high-mileage motor IMO.

A lot depends upon how deep and expensive you are willing to go here. If your time is more plentiful than you money, then you can do a lot yourself, but far less efficiently than someone with all the right tools and know-how.

Head bolt removal was straight forward. No problems at all removing them. Can these be reused or not recommended to do?

Well, that's a $700 question. Those bolts look like they are in very good shape. No rust. I'm not a believer in the theory that the head bolts are "torque-to-yield" bolts that can only be used once. I am a believer in metal fatigue however.

Maybe @Geza-aka-Zombo can do some math with one or more sets of assumptions and come to a more-objective conclusion on that.

A couple of years ago I would have written: "Think carefully about skimping on the build."

These days, the new head bolts (at least the longer ones for '89+ heads) have no grade or maker's mark on their heads. It's not clear "what" they are without destructive testing. They leave me feeling uneasy about their use.

I can tell you that I'm building an '87 motor right now that I am pretty sure has 30k-miles or less on it. The head bolts look better - slightly - than yours and I'm not going to buy new ones...

... unless, when I torque them they turn "funny." My Stahlwille torque wrench used pretty-much only for engine builds shows torque and angle simultaneously so that I can see if a head bolt is yielding when I do the 90° turns.

[WyattsRide]

Thanks WORF but I'm even further on my head removal than I have posted. This may be a problem. I don't know.

It is what it is. Either the cams are in four pieces and straight, or they are not.

Well there are 4 cams and they are not in any pieces. They seemed straight when we carefully removed them. We did not have the special hold down Porsche tool though. I only dropped them twice. HA just kidding!

He stated the timing was off 5 to 6 teeth when he got it

That'll probably do it.

Right side. Looks to us that the gasket was in great shape and no corrosion around the seal. The cylinders are all in perfect shape with no scoring. Just a lot of carbon on the piston heads. Are better pictures needed to confirm?

Left side
Same as the right side as far as conditions. Are better pictures needed to confirm?

A calibrated Mark I eyeball looking close up is better than pictures.

If you say that you don't see any scoring then I don't need pictures to prove it.

What I do see is "shiny" spots in the carbon for the piston relief surfaces of all the exhaust valves. My expectation - just from the 'far away' pictures - is that all the exhaust valves are bent. If indeed it was the skipping belt that caused the engine to stop, then you know you have to have some bent valves somewhere.

I expect that due to the compression test done by my indy.

I trust that the crank and pistons turn nice and smooth in the short block?

Yes, they turn smoothly when we rotated the crank

One thing you can do with some make-your-own-apparatus skills is to do a leak-down test of the short block and make sure you've got consistent leak-down across all 8 holes. That will give you a good indication of if you need to go further with wrenches.

Can you elaborate on this more?

For the heads, I would like to see a picture of each head's deck surface. I might ask to zoom in on certain sections after that. You don't want any corrosion within roughly 2mm of the edge of the fire ring and any deep holes should be 'dealt' with.

I will provide pics soon


On the other hand, you can't really see how bad the corrosion is until the heads are soda blasted.

On the gripping hand, if valve contact has occurred then you're probably going to "do" the heads and a light decking - minimum - is going to be part of that.


When I have a set of heads on the bench these days, they always go to "my guy" for a thorough job. It doesn't make a lot of sense to go this far and not do that on a high-mileage motor IMO.

I will be sending out the heads to a Co that my indy uses or I will talk with Pete K about using his guy. I don't plan on doing anything myself with the heads. The only thing I'm not sure about is, do I leave everything as is and give the whole things to let them evaluate?

A lot depends upon how deep and expensive you are willing to go here. If your time is more plentiful than you money, then you can do a lot yourself, but far less efficiently than someone with all the right tools and know-how.

I have time. No money

Head bolt removal was straight forward. No problems at all removing them. Can these be reused or not recommended to do?

Well, that's a $700 question. Those bolts look like they are in very good shape. No rust. I'm not a believer in the theory that the head bolts are "torque-to-yield" bolts that can only be used once. I am a believer in metal fatigue however.

Maybe @Geza-aka-Zombo can do some math with one or more sets of assumptions and come to a more-objective conclusion on that.

I'm hoping I can reuse. But if the consensus is to not reuse, then it is what it is. I'll go new.


A couple of years ago I would have written: "Think carefully about skimping on the build."

These days, the new head bolts (at least the longer ones for '89+ heads) have no grade or maker's mark on their heads. It's not clear "what" they are without destructive testing. They leave me feeling uneasy about their use.

I can tell you that I'm building an '87 motor right now that I am pretty sure has 30k-miles or less on it. The head bolts look better - slightly - than yours and I'm not going to buy new ones...

... unless, when I torque them they turn "funny." My Stahlwille torque wrench used pretty-much only for engine builds shows torque and angle simultaneously so that I can see if a head bolt is yielding when I do the 90° turns.

[tungsten]

Have you pulled the heads before in your ownership? An ‘85 would have left Stuttgart with studs instead of bolts, so those may be a much newer vintage of steel than original.

[worf]

Have you pulled the heads before in your ownership? An ‘85 would have left Stuttgart with studs instead of bolts, so those may be a much newer vintage of steel than original.

Good point. I know the 86.5s use bolts and all the 16v use studs. Never thought about an '85 S3 engine.

The shop manual is silent on when the 32v engines when to bolts. It's probably in on of the year-by-year info books.

[linderpat]

to further elaborate, I'm the other guy working on this with Rick. We disassembled the heads on Sunday. Everything came apart smoothly, without drama. Camsare safely tucked away. No wear on the lobe surfaces either. They appear in great shape.

There is zero corrosion on the block and the head surfaces, and the gaskets were in great shape. It makes me wonder if the heads were done before Rick got the car. It used to be Steve G's car, so he may know and it is worth the ask. I am, also curious about the bolts, as I thought studs were used too.

As to the cylinders - no scoring. they are near flawless. The crank turns smoothly. The piston tops are carbon covered, but that may be the normal state, all things considered. It isn't that thick. Also, in real light in the garage, I saw no evidence of valve contact on the piston surfaces. There were no shiny marks at all. All of the valves appear to be seated properly, but we won't know until they are pulled out of the head.

Question - do the lifters have to stay in the order they come out? Also, some of them are sticking. should they be cleaned? I read on rennlist from Greg and maybe you too Dave, that these lifters can't really be effectively cleaned. What's the good word on that?

Thanks guys.

[ChrisZ]

Interesting post, and I'll be following this closely. Question: How do your cam chain tensioners look including the pads? I had one of the newer pads break on my 944S at 200k miles and it resulted in an exceptionally sad condition (took out the cams, cam chain, tensioner mounting point, and 12 valves if I recall). Took me a year to put it back together myself, but now everything is totally happy on that motor.

While the 928S is much gentler on the tensioner pads (engine turns 2000rpm at 60mph instead of 3000, engine lives most of its life at lower RPMs, etc) I fear a failure of them a LOT more than a simple timing belt fail.

[WyattsRide]

Have you pulled the heads before in your ownership? An ‘85 would have left Stuttgart with studs instead of bolts, so those may be a much newer vintage of steel than original.

I have not pulled the heads in my ownership which has been 13 years. I will contact the previous owner and ask if he did during his ownership which was I think, at least 8 years. He was a very proactive owner and did a lot of thorough maintenance. I don't remember him saying he ever had the engine pulled for anything.

Interesting post, and I'll be following this closely. Question: How do your cam chain tensioners look including the pads? I had one of the newer pads break on my 944S at 200k miles and it resulted in an exceptionally sad condition (took out the cams, cam chain, tensioner mounting point, and 12 valves if I recall). Took me a year to put it back together myself, but now everything is totally happy on that motor.

While the 928S is much gentler on the tensioner pads (engine turns 2000rpm at 60mph instead of 3000, engine lives most of its life at lower RPMs, etc) I fear a failure of them a LOT more than a simple timing belt fail.

This is a good point to discuss here. I will provide pictures of the chain tensioners for recommendations. I don't have any idea on what to look for. Thank you!

[worf]

Well there are 4 cams and they are not in any pieces.

Four pieces. One cam per piece is good.

One thing you can do with some make-your-own-apparatus skills is to do a leak-down test of the short block and make sure you've got consistent leak-down across all 8 holes. That will give you a good indication of if you need to go further with wrenches.

Can you elaborate on this more?

It's pretty simple, but the diagnostic value is somewhat lacking. It will tell if you've got a serious problem only.

What you do is get a hunk of metal or a piece of thick wood will do - that's what I did - that is exactly big enough to cover a cylinder and the four studs/head bolt holes around the cylinder.

- Get a rubber o-ring/gasket from your local hardware store that's as close as possible to the width and diameter of the cylinder wall.
- Route a shallow circular channel in the wood and glue the o-ring into it.
- Drill five holes in the "device": one for each "head bolt" and one in the center.
- Drill/tap/glue - whatever - an air-tool fitting that works with your leak-down tester to the center hole.
- Bolt this contraption to the cylinder with four head bolts to seal it.
- Attach your leak-down tester, air source, and do a leak down test.

All cylinders should be very-very close to the same leak down numbers.

If you have one or more holes that are 'off' then you have a sealing problem.

If you want to get more "ghetto sophisticated" you can
- do this test at several source pressures
and
- rotate the crank to move the piston from TDC to BDC and back during the test as a poor-man's(*) way to see if you've got problem spots on the cylinder walls.

(*) My "head guy" has a CNC cylinder honing machine. After seeing that thing in action, everything else is a "poor man's" device now.

I will be sending out the heads to a Co that my indy uses or I will talk with Pete K about using his guy. I don't plan on doing anything myself with the heads. The only thing I'm not sure about is, do I leave everything as is and give the whole things to let them evaluate?

You need to talk to 'the guy' that's going to "do" the heads to figure out what he's good at and with what he's not experienced or what he does not expect to do. Ideally your 'guy' has done a bunch of 944/968/928 heads, and then ...
- will want the heads with valves and springs still installed, one set of cams, and ALL of the cam bridges and a box of new valve stem seals.
- will tell you to remove oil check valves, plugs, lifters (obviously.)
- will have the tech specs for a 928 head on-hand, or will know enough to ask you for them
- understands that he has to deal with freeze plug removal and replacement and knows the tricks for 944/968/928 heads
- can source valve spring shims, stem retainers, valves
- is experienced at setting up the valve springs, etc.

Start by asking him what he expects you to bring to him and then ask questions based upon the list above. Does he expect you to tell him which valves are bent? Is he just going to do the machine work, hand the "empty" heads to you so that you can get the metal shavings out? Etc.

A lot depends upon how deep and expensive you are willing to go here. If your time is more plentiful than you money, then you can do a lot yourself, but far less efficiently than someone with all the right tools and know-how.

I have time. No money

The big variable here then, is how much of the head work you can confidently do yourself or what you will HAVE to do yourself. And also, if the heads required welding (due to corrosion.) In that case, I would want 'the head guy' to be responsible for the complete assembly.

I'm hoping I can reuse. But if the consensus is to not reuse, then it is what it is. I'll go new.

See if you can figure out how many miles are on them since it does seem like the heads have been off before. They appear to be reusable to me. But, again, if the new head bolts had maker's marks and grade on them, my answer would lean more toward replacing.

ONE THING that bothers me about this, is that so far, it seems that there's no indication of the cause of the "dreadful sound screeched from the engine bay" and why it "Would not start again" ... because ...

Also, in real light in the garage, I saw no evidence of valve contact on the piston surfaces. There were no shiny marks at all. All of the valves appear to be seated properly, but we won't know until they are pulled out of the head.

... this -^. If there's no indication on the piston top of valve contact or on the valve faces of piston contact then the belt didn't jump enough to be the cause.

Or, else, I'm totally missing something here.

If one or more valves is sufficiently bent that the car won't start then I damn well would expect to see evidence that is very obvious.

In my experience, most 32v 928s with "all original" heads have one or five valves that are slightly bent and it doesn't keep the motor from running half-decently.

There is zero corrosion on the block and the head surfaces, and the gaskets were in great shape. It makes me wonder if the heads were done before Rick got the car. It used to be Steve G's car, so he may know and it is worth the ask. I am, also curious about the bolts, as I thought studs were used too.

I will assume you've seen enough pictures of head deck corrosion that when you write zero you know what that means.

This, then, along with the bolts rather than studs, pretty much means that the heads have been off before. QED.

At this point, then, I would do nothing further with the heads and wrenches, until I was confident I knew the actual failure mode.

I think some information or observations are missing from this story, if you folks are confident with the failure mode and I can't see it. (Or, maybe my "entire head" isn't in this yet.)

As to the cylinders - no scoring. they are near flawless. The crank turns smoothly. The piston tops are carbon covered, but that may be the normal state, all things considered. It isn't that thick.

Did anyone attempt to turn the crank while the t-belt was still strung?

Question - do the lifters have to stay in the order they come out?

That is considered best practice. You can use three labeled clear plastic egg crates to keep the lifters organized. Hope the lifter horse is still in the barn.

Also, some of them are sticking.

Describe what you mean by "sticking."

should they be cleaned? I read on rennlist from Greg and maybe you too Dave, that these lifters can't really be effectively cleaned. What's the good word on that?

16v lifters can be disassembled (once.) 32v lifters can be disassembled either partially or completely and reassembled such that they are no worse for wear. Although complete disassembly is best done with a jig made for the purpose.

The answer to the "effectively" question depends upon the failure mode and how far you want to go with disassembly and cleaning in order to save the $1700 (minimum) expense for new lifters. (Unless you want to use the cheap VW lifters that seem to have a "debatable" reputation.)

With no failure mode - as far as I can tell - identified, it's too early to talk about lifters.

[worf]

Interesting post, and I'll be following this closely. Question: How do your cam chain tensioners look including the pads? I had one of the newer pads break on my 944S at 200k miles and it resulted in an exceptionally sad condition (took out the cams, cam chain, tensioner mounting point, and 12 valves if I recall). Took me a year to put it back together myself, but now everything is totally happy on that motor.

While the 928S is much gentler on the tensioner pads (engine turns 2000rpm at 60mph instead of 3000, engine lives most of its life at lower RPMs, etc) I fear a failure of them a LOT more than a simple timing belt fail.

The 944 appears to be legendary for eating its cam chain tensioner. I had a colleague last century that owned a 944 just long enough to have it feast on its chain tensioner a month or three after the warranty expired.

My *opinion* based upon never having seen what a 944 poops when it eats a chain tensioner, but having read about 944s and having seen a lot of 928 tensioners over the decades is that the 944 needs new pads every 75k-miles whereas the 928 needs them at 150k-miles or when they are 25+ years old and the pads have become brittle. I think that the primary reason for this is the angle of the head. On the 944 the head is much closer to 'upright' whereas the 928 is at a 45-degree angle.

Oil drains from the 944 head far better than the 928 head. The 928 head is filled with oil. The chain tensioner in the 944 gets "splashed" with oil whereas the 928 chain tensioners are more-or-less bathed in it.

That's -^ my opinion.

None of that is intended to mean that Wyattsride shouldn't contemplate the vicissitudes of his chain tensioners and pads carefully. Although, given what's "here" in the thread, I can't imagine that they are root cause. If they were there'd be obvious cam chain tensioner poop somewhere.

[linderpat]

This is really good stuff, and Dave your insights are invaluable!

As to whether the crank was turned with the belt on, Rick's indy did realign timing and the car was able to be started and moved under its own power, albeit roughly running. While the piston tops looked like no apparent valve contact, the bottom of the heads show a few valves that are slightly elevated out of their seats, which may mean slight bending? The leakdown that Rick posted above certainly indicates big leaks at cyl's 1, 2 and 5.

Fortunately, we were smart enough to leave everything together on the heads (lifter horse was in the barn ). Rick has since pulled the lifters, labeled and stored for later examination/cleaning etc. When I said a few of them appeared to be stuck, I meant that when you push on most of them in the head, they go down and spring right back up. A few would not go down when pushed (finger pressure).

[tungsten]

I have not pulled the heads in my ownership which has been 13 years. I will contact the previous owner and ask if he did during his ownership which was I think, at least 8 years. He was a very proactive owner and did a lot of thorough maintenance. I don't remember him saying he ever had the engine pulled for anything.

I’m pretty confident someone did during its history. This thread sent me down the rabbit hole, ‘87 Service Info book was the first mention of the switch to bolts, and PET shows studs all the way through the end of ‘86 production.

[WyattsRide]

Thanks Dave for all your replies. And everyone else's!

I will try to address your questions (and anyone else's) the best I can with my limited knowledge. Also, please understand our (Ed and mine) observations and condition opinions are based on online experiences from reading RL and other forums for years and some real life engine work. Ed has a lot more experience than I do. But, this is both of our firsts, diving this deep into an engine. I come here seeking advice and direction from guys like you, that have done this many times.

Here are the head surface pictures.
Left (drivers) Side


Right Side


Besides the gasket residue, to me, there doesn't seem like much at all or any, surface corrosion.

I probably need more light, so that the valves are more visible?

[WyattsRide]

Cam Shaft tensioners and chains. (I admit that now that they are out, I can't remember what side is the pad side. I will eventually figure this out. I'm thinking the black part )

Left side




Right side




Are my pictures too dark? I can't tell from my work computer. Everything is dark to me on this computer.

[WyattsRide]

I tagged, took a picture and then removed the lifters and boxed them. The tape helped protect the top surface when I used a magnet to pull them out. They all came out nice and smooth.

[linderpat]

Interesting - a couple of those valves do like like they have shiny edges. I didn't notice that on Sunday, although we didn't look closely at the underside of the heads because we didn't want the lifters to fall out.

[Mrmerlin]

Well you are moving right along,
if you look at the pictures of the heads you can see all of the exhaust valves have the lower edges carbon chipped off,
these indicate that all of the EX valves have contacted the pistons.
NOTE the same indications are on the pistons with chipped carbon,
NOTE clean the piston tops s and look for cracks where the valves hit , the pistons will probably be OK.
so a good chance your going for new valves really any valve that shows this damage should be replaced even if it not bent,
as it could fracture later and thus the head of the valve could come off and take out the piston
measure the valve guide clearance as well the guides could also be damaged ovaled.

I would swap in new cam chains, use the 951 turbo chains, they are stronger , get new pads for the tensioners
I agree with Dave here ,I would reuse the head bolts they look good.
head surfaces look great,
NOTE make sure to measure the heads before you send them off to verify the height REF WSM for how and where to take this measurement.
NOTE this so they dont cut off too much then it requires different thickness head gaskets.
hand fit the water bridge with no gaskets or O rings to the assembled engine ,
file to fit the feet as the angle will be off since the heads will be cut, its not too hard to do this.
otherwise the feet may leak.
Get a used set of cam cover bolts from 928 INTL to replace the standoff junkers

[WyattsRide]

Yes Stan we are moving along.

Sorry I didn't keep you updated on our progress after our last talk. I thought I bothered you enough. But, I was hoping you'd see this thread and contribute.

I'll get some more clear lighter pictures soon.

[linderpat]

Don't worry too much about bothering Stan or Dave, because they both know with absolute certainty that after this, you and I Rick will never effin do this job again, and just hand out Stan and Dave's respective phone numbers





I keed, I keed, sort of. The job so far hasn't been too bad, and Stan Dave and a couple of others have made all the difference in the world.

[worf]

As to whether the crank was turned with the belt on, Rick's indy did realign timing and the car was able to be started and moved under its own power, albeit roughly running.

Ah hah! That is the missing observation that links to a root cause for failure to start.

The "dreadful [screech] sound" is still something to chase down though. Valves bend silently (more-or-less in the context of all the other noises an engine makes.) A screeching noise is, most-probably, metal on metal not under the valve cover.

When the crank is trying to use the timing belt to push the valves through the piston tops, almost everything in bewteen is subjected to stress for which it wasn't designed. The cause of the noise requires further investigation.


@WyattsRide
What do the cam noses and the back side of the cam gears look like?

What do the cam nose bolts and their hexagonal think washers look like? (Best plan on replacing the bolts and washers, or at least new bolts and resurfaced washers.)

The Woodruff keys and key ways?

Or, in other words, did the timing belt 'drag' the cam gear around the cam nose until the gear was stopped by the key?

That'll make a noise.

How about the bolts for the rotors?

@Mrmerlin may have better thoughts on what might cause a dreadful screech while the piston tops are bending valves.

Inspect everything that would have been subjected to "improper" stress and look for something that would explain the screech. Whatever it was (or they were) may not be good for reuse.

While the piston tops looked like no apparent valve contact, the bottom of the heads show a few valves that are slightly elevated out of their seats, which may mean slight bending? The leakdown that Rick posted above certainly indicates big leaks at cyl's 1, 2 and 5.

As you read from Stan, he concurs with my initial assessment that there are numerous bent exhaust valves.

I'm going to bet that "the head guy" can instantly identify which valves definitely hit pistons. Furthermore some of the valves that don't show damage on the face are probably bent too.

@WyattsRide
Be prepared to replace a bunch of valves.

Taking note of Stan's list of things that need to be checked in the heads:
- valve guides, clearance
- valve seats
- spring perch surfaces, springs, hats
- keeper grooves and keepers in any valves that are 'good'
- cam bearing surfaces on heads and bridges.

Every single piece in the head may have been subjected to "breaking" force.

A good head guy will know all of that and more. In the context of a valve bending event they should know what must be checked. A great head guy would check everything no matter what.

When I said a few of them appeared to be stuck, I meant that when you push on most of them in the head, they go down and spring right back up. A few would not go down when pushed (finger pressure).

Lifters that feeling "springy" when they are still in the head (or when on their back and you're pushing "the button" (spring-loaded plunger assembly) via your finger) have no oil in "the button"; they are empty of oil. That may or may not be a problem. Lifters' plungers leak down. It's the speed of leak down that matters.

Lifters with plunger assemblies full of oil do NOT feel springy.


@WyattsRide
This - lifters - may be an area where you can save some money by spending a lot of time. But, I think that talking about lifters is still a distraction at this point.

Here are the head surface pictures.
...
Besides the gasket residue, to me, there doesn't seem like much at all or any, surface corrosion.

Stan writes that they look great. I'm going to write that they don't look obviously bad. Stan's a half-full guy and I'm a half empty guy. (But this glass has piss in it else the motor would still be in the car. :) )

All of the brown/white stuff is gasket, corrosion, or some of both. It's normal. The question is how deep is any corrosion? Is it just a "stain" or is there a "pit" under the stain?

Since the heads are definitely going to a shop for rework it's not imperative that we determine the level of corrosion in the half-full/half-empty glass. The shop's first step after complete disassembly *should* be to soda blast them at which point pitting will be revealed. At that point the 'clean' heads can be inspected to see if any of the pitting is close enough to the fire rings to require welding.

[Mrmerlin]

about that screeching noise I wonder if it could have been the tensioner pulley hitting something as the piston lost pressure,
I dont know enough about the Porkensioners to know the nuances.,
I am also taking for granted that the head shop will be inspecting the the whole head/valve system for damage due to a untimed belt episode.

The exhaust valves are just the most obvious thing I can see from a picture, but yes Dave is right you could also have a bunch of bent intake valves
When I pulled the heads off the 88 I did, the corrosion was pretty bad and easily seen , Lorenzos did a great job rehabbing them.

[The Fat Man]

Multiple person reply here:

Rick: I still have those raggedy 1985 S3 heads with good valves. You are welcome to any that you can use.

Dave: 1986.5 S3 heads still use studs to retain them.

Ed, Rick, and crew: bang up job on the work you have done!

[worf]

Good point. I know the 86.5s use bolts and all the 16v use studs. Never thought about an '85 S3 engine.

Dave: 1986.5 S3 heads still use studs to retain them.

It seems likely that I'm guilty of using a data set where N=1 to form my conclusion. And I'm reminded that as the fleet ages using today's observations to form definite conclusions about original condition is a trap.

Last November I built an 86.5 long block that had both head bolts and S4 chain tensioners.

History of that motor is unknown to me. Perhaps it suffered a prior valve crash and was rebuilt to "S4 specs" by a shop that knew what it was doing.

The latter sentence fragment seems like it should have a high probability of being an oxymoron though.

[Daniel5691]

Good point. I know the 86.5s use bolts and all the 16v use studs. Never thought about an '85 S3 engine.

Dave: 1986.5 S3 heads still use studs to retain them.

It seems likely that I'm guilty of using a data set where N=1 to form my conclusion. And I'm reminded that as the fleet ages using today's observations to form definite conclusions about original condition is a trap.

Last November I built an 86.5 long block that had both head bolts and S4 chain tensioners.

History of that motor is unknown to me. Perhaps it suffered a prior valve crash and was rebuilt to "S4 specs" by a shop that knew what it was doing.

The latter sentence fragment seems like it should have a high probability of being an oxymoron though.

Very interesting. At this point, a lot of what we seem to do has as much to do with forensic archeology as anything else...

[The Fat Man]

Dave, I too only have a sample size of N = 1, however, I have done alot of perusing of TOS, PET, and the internet in my 928 lunacy. 1986.5 S3's are a freak hybrid of S3/S4. 1986 S3 has studs for head retension and orginal S3 style chain dampers. 1986.5 has studs for head retension and S4 style chain dampers with specific 1986.5 S3 oil pipes for them. S4 oil pipes do NOT fit without 'massaging.' 1987+ S4 has bolts for cylinder head retension and S4 style chain dampers with S4 oil pipes.

Now, backdating an S3 block is a matter of heating and removing the studs, and cleaning the threaded holes. Then S4 bolts are fitted to secure the heads.
Granted, I have not done this myself, just read about it. Alot.


Disregarding all that, Rick's engine is currently fitted with bolts, and should go back together as such. New studs are a can of worms...
(If you listen really closely, you can hear that I am pretending to know what I am talking about. )

[linderpat]

what's interesting are the variations in these motors from the same years. Rick has many little differences from mine, even things like fuel lines and some ground wires Mine is all original; not much was ever done to it before I got it. It is an early 85, and Rick's is later. Also, I am on my second 85, and had an 86.5. There are lots of little differences in these S3 engines from one car to the next, and maybe depended upon what was in the parts bin on the day the car was assembled.

[worf]

Now, backdating an S3 block is a matter of heating and removing the studs, and cleaning the threaded holes. Then S4 bolts are fitted to secure the heads.

Yep. Can you imagine Acme European Performance Werks of North-NorthWest Tumbleweed North Dakota doing that?

I can’t. Possible. But about as probable as an honest politician. Even less imaginable that a dealer would have done it.

I will note that wyattride’s head bolts look exactly like the ones I pulled out of an early’87 squirter block a few weeks ago. Later-engine OE head bolts are not black.

It’s all very curious. But, no “decision” is required. It’s all data.

[WyattsRide]

Rick: I still have those raggedy 1985 S3 heads with good valves. You are welcome to any that you can use.

Sorry I haven't been around lately. Been really busy at work.

Last update is, just in the process of cleaning the piston heads. Nothing aggressive. Just enough to get off the carbon.

My indy mechanic came over the house on Saturday to have a look at our progress. He said that from the looks of the carbon removed on the piston heads at the Exhaust Valve relief area, that all the Exhaust Valves are probably damaged. He feels from the look of the pistons that the Intake Valves are OK. But, won't know for sure until the "head guy" goes through them. My indy mech has a "head guy" that he trusts. I will be giving the heads over soon.

Question - Above, Seth has offered me good "Used" valves. Is re-using good used valves OK to do?

[worf]

Question - Above, Seth has offered me good "Used" valves. Is re-using good used valves OK to do?

In principle it’s fine. As long as they are ‘good.’ Get’em all and send them along with the heads to the head guy. Expect that you’ll still need to source a couple of exhaust valves; not 100% chance that all 16 used exhaust valves are good (unless Seth’s head guy has so pronounced them.)

[JBRob007]

Just catching up on here... Great work you guys and you've got the 928 "brain trust" on line as well... except Seth Seriously, wishing you all well in this endeavor. We've rarely gotten in past the heads and only ONCE did a full engine rebuild - that was for Brett's S4 "Rosy" and even that limited experience was 10 years ago. Time flies when you're having fun! Keep at it

[The Fat Man]

Just catching up on here... Great work you guys and you've got the 928 "brain trust" on line as well... except Seth Seriously, wishing you all well in this endeavor. We've rarely gotten in past the heads and only ONCE did a full engine rebuild - that was for Brett's S4 "Rosy" and even that limited experience was 10 years ago. Time flies when you're having fun! Keep at it

Awww man...

[The Fat Man]

Question - Above, Seth has offered me good "Used" valves. Is re-using good used valves OK to do?

In principle it’s fine. As long as they are ‘good.’ Get’em all and send them along with the heads to the head guy. Expect that you’ll still need to source a couple of exhaust valves; not 100% chance that all 16 used exhaust valves are good (unless Seth’s head guy has so pronounced them.)

Uhhh...no. These are a tad on the ghetto side. I made a foolish purchase a few years ago of a set of 1985 S3 heads purported to have low mileage. I bought them on the sight of the head deck surfaces being in excellent condition. Too bad the heads came from an engine that suffered oiling system failure. All the cam journals are rough. But, the heads are complete, with all 32 valves, springs, etc...

I am offering them to Rick as a 'gimme' in exchange for a bag of cheeseburgers, and as a show of friendship. It is my assumption that they will have to be machined with the heads for a valve job. And or have the valve guides redone as well. Looking at Auto Atlanta, I am going to assume there is a typo, as exhaust valves are listed as $299.21. Each.

[worf]

... , as exhaust valves are listed as $299.21. Each.

So... note what I wrote above, excerpted below for convenience with added-by-me emphasis:

You need to talk to 'the guy' ... Ideally your 'guy' has done a bunch of 944/968/928 heads, and then ...
...
- can source valve spring shims, stem retainers, valves
...

I should have added parenthetically after "valves:" "that aren't made of gold."

Mark lists used exhaust valves for $100 each.

"My guy" gets new ones from a source in Germany for ~$45 each (for S4-size valves.)

[The Fat Man]

Mark lists used exhaust valves for $100 each.

[WyattsRide]

Finished the piston cleaning over the weekend. Also did the head surfaces. They look pretty nice and are very smooth with no pitting.

Right side. Head surface not cleaned on this pic. Just the pistons.


Left side all cleaned.

[worf]

Left side all cleaned.

That picture is prima facie evidence that the cylinder block has been decked. I have *never* seen a 928 cylinder block just "clean up" that well.

So, both the block and heads have been decked once before and explains why the studs were removed from the block.

If you are going to install, again, the Porken Tensioner when you are done, you should consult with Ken about getting a custom bracket to push the main roller closer to the center of the block.

[WyattsRide]

Left side all cleaned.

That picture is prima facie evidence that the cylinder block has been decked. I have *never* seen a 928 cylinder block just "clean up" that well.

So, both the block and heads have been decked once before and explains why the studs were removed from the block.

If you are going to install, again, the Porken Tensioner when you are done, you should consult with Ken about getting a custom bracket to push the main roller closer to the center of the block.

I'll put a little more light on the subject. There's approximately 17 years of unknown service from the time the car was new and when my previous owner bought the car in 2002.

I plan on putting the OEM Belt Tensioner back on this engine..... After refurbish.

[The Fat Man]

Left side all cleaned.

That picture is prima facie evidence that the cylinder block has been decked. I have *never* seen a 928 cylinder block just "clean up" that well.

So, both the block and heads have been decked once before and explains why the studs were removed from the block.

If you are going to install, again, the Porken Tensioner when you are done, you should consult with Ken about getting a custom bracket to push the main roller closer to the center of the block.

May I also suggest measuring the height of the cylinder heads in accordance with the WSM? To see how much the cylinder heads were machined. And whether Rick needs to consider the special 'thicker' head gaskets for heavily machined heads.


Looking good, Rick!

[worf]

I'll put a little more light on the subject. There's approximately 17 years of unknown service from the time the car was new and when my previous owner bought the car in 2002.

I think it was understood that some of the history was lost. There was the puzzle - at least in my mind - of head bolts vs studs and the educated guess that the studs had been deleted when the heads were - probably - previously removed.

My comment was intended along the lines of: well, that ship has now sailed. The cylinder block has been decked. That would have required removal of the head studs. So, now we pretty much know that this is the motor's second "open heart" operation.

I plan on putting the OEM Belt Tensioner back on this engine..... After refurbish.

I think that is a wise idea.

May I also suggest measuring the height of the cylinder heads in accordance with the WSM? To see how much the cylinder heads were machined. And whether Rick needs to consider the special 'thicker' head gaskets for heavily machined heads.

Given that it's now certain that everything's been decked before... yeah. Pretty much should do that.

It might also be interesting to calculate the new static compression ratio and see where it's at with either the standard or extra-thick gaskets.

I seem to recall reading on TOS that the thick gaskets were NLA. But as of this morning several sites show them as available. Might all be lies, damned lies and old java script though.

[maddog2020]

check the cam journals and caps very carefully. screeching sounds are usually metal on metal. also split the block and check rod and main bearings. if everything looks good no harm just more work and cleaning. you can number the pistons, and clean them really well, and re assemble without removing the rings. find a deck bridge on summit and than you can see if the pistons are protruding from the block, and see how much rock you have in the pistons. this will also give you an idea how much was taken off the block.

If you decide to do the main bearings you can cheat the cost by half, and buy the 944 main bearings set by glyco, and buy a porsche thrust bearing.

[WyattsRide]

I can't find head measurement tolerances for MY 85 heads in the WS Manual. I did find them for the 16V at 15-19. Can anyone direct me where in the WS Manual or where to measure and what the measurements should be?