8 cylinder front engine iconic vehicle
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By jschiller
#207887
I am gathering parts for an engine-out head gasket job on my 1989 S4 5sp. The engine has 165k miles on it so its way overdue to have the gaskets checked. I'm pulling the engine so I can do the timing belt/water pump, motor mounts and other while-I'm-in-there goodies at the same time. I don't find a definitive answer in my searches on whether I can safely reuse the head bolts or if I need to budget an extra $1k or so for them. I gather a visual examination after removal doesn't tell you much.

I have fairly complete maintenance records for the last 80k miles and the engine has never been touched except for peripherals like TB/WP, cam gears, top end reseal, air conditioning, etc. so I am certain that the heads have never been off and the bolts never reused.

What does the brain trust think? New bolts are going to about double my costs on this job so is the insurance worth it? I expect I am going to find a lot of other things will need to be replaced anyway once the teardown has started and that $1k for bolts will be useful if I don't need them.
By worf
#207901
jschiller wrote: Wed Mar 29, 2023 6:12 pm I am gathering parts for an engine-out head gasket job on my 1989 S4 5sp.

...

New bolts are going to about double my costs on this job so is the insurance worth it?
I highly doubt that $1k worth of bolts will double your actual out-the-door cost. If that is the case then you are not planning to replace a bunch of stuff you probably should and you also have a machine shop, are skilled with aluminum welding, and have done 928 heads before. At 165k you should do a head job. You will have some guides out of spec and I'd be shocked if you didn't have at least one bent valve. You should expect some welding to be required to fix damaged areas on the head deck.

My last estimate for JUST the parts for an on-stand motor rebuild where everything is needed is $9k to $16k depending upon the state of things like plug wires, cam gears, rod bearings, etc. That doesn't include labor or outside services (machine shop, etc.) But, it does include all wear items like belts, all hoses, cam chains and pads, and everything else that's rubber or a roller or a sender known to die (CPS, knock sensors, WOT switch, etc.)

If you already have done a bunch of stuff - intake refresh, plug wires, fuel lines, cooler lines, etc. - and are not including the cost of a pro doing the head job then maybe you can get away with skipping most of the expensive stuff in that 9-16k. But, just the parts for a thorough t-belt job are closer to $1k than $500 these days.

A new set of bolts should be under $800. Still ridiculously expensive for 20 bolts. I get it.

jschiller wrote: Wed Mar 29, 2023 6:12 pm I don't find a definitive answer in my searches on whether I can safely reuse the head bolts or if I need to budget an extra $1k or so for them. I gather a visual examination after removal doesn't tell you much.
A visual inspection will tell you if they are rusted. If they are rusted then they are done.

What it won't tell you is if they have "fatigued" out. I am of the opinion that the head bolts are not 'torque-to-yield' bolts but that doesn't mean that they won't succumb to fatigue from repeated hot/cold stretch/shrink cycles eventually.

I wouldn't rebuild your 928 motor without new head bolts. I don't have a specific cut-off for mileage. The motors I get tend to have no more than 50k or 100k+. On the former I have reused head bolts on most occasions. On the latter only once because the state of head decks, bolts, etc., was like a 928 with half the mileage.

My advice would be to wait until you have everything in pieces and see what your actual costs will be and what your bolts look like.
SeanR, Mrmerlin liked this
By jschiller
#207912
Thanks for the reply, Dave. My mistake. I didn't state clearly enough where that (additional) $2k outlay was coming from. I already have the TB/WP job parts on hand (rollers, seals and all other small bits). My figure of $2k was based on the additional new parts/labor I would need if everything was good after the teardown. Of course, I know it will not. But even then, I can see my estimate was pretty far off. My car was well maintained by the previous 2 owners and a lot of the external parts were properly replaced, more or less as needed. But I hadn't reckoned with some of the items you mentioned...cam chains, pads and other internal parts, head work, etc., so I think I need to make an upward adjustment to the budget and add in the head bolts as well. I just hope the heads are not too far gone to salvage.
By Sazerac
#208516
Yes, your last sentence in the post immediately above was what I was thinking. Don't forget to budget some money for some kind of head restoration work. On the optimistic side, my wild guess is that you can assume USD 1'500 - USD 2'000.
By worf
#208539
jschiller wrote: Wed Mar 29, 2023 9:39 pm My car was well maintained by the previous 2 owners and a lot of the external parts were properly replaced, more or less as needed.
This -^ is the mental model that needs to be thoroughly examined. At 165k-miles and over 30 years old, what parts, not already replaced recently, have lived their expected lifetimes? Are you treating this like "maintenance" or "restoration?" And what kind of "maintenance?"

Would you fly on an aircraft where it was only "maintained" when it was broken?

How reliable do you want your 928 to be? How often do you want to "go back in?"

Once you have the heads off, you will have disturbed almost every single gasket on the motor. Are you going to reuse the pressure washers for the intake or cam covers? Intake gaskets? Cam cover spark plug well gaskets? What about injector o-rings? Breather hoses to the ISV and air guide? CPS? Knock sensors? Motor mounts? Rusty fasteners?

Only you can answer those questions. It is up to you since you are "warrantying" your work.

But, we are here to help.
By worf
#208541
jschiller wrote: Wed Mar 29, 2023 9:39 pm I just hope the heads are not too far gone to salvage.
The guy that does my heads has told me "no heads are too far gone to salvage." The caveat is that heads can be so far gone that the cost to salvage them is in excess of getting used heads that don't require as much "salvation."

However, my personal experience is that, so far, '87 to '89 heads are more robust that '90+ heads. If you have records that show a good history of coolant changes (every 2 to 5 years) then your '89 heads will not be in the too-far-gone category. On the other hand if you have no history or the history you have is poor, then expect you heads to require some welding.

You can get a 'feel' for how much damage has occurred once the heads are on the bench and you can look at the deck and old gaskets. But, you can't know with confidence until the head decks have been soda blasted.
By jschiller
#208564
worf wrote: Sun Apr 02, 2023 8:42 pm
jschiller wrote: Wed Mar 29, 2023 9:39 pm I just hope the heads are not too far gone to salvage.
If you have records that show a good history of coolant changes (every 2 to 5 years) then your '89 heads will not be in the too-far-gone category. On the other hand if you have no history or the history you have is poor, then expect you heads to require some welding.

My goal is more a restoration of the mechanicals than maintenance so everything will be replaced that I can source (seals, gaskets, timing chains & pads, etc). I plan on pulling at least one rod bearing cap but I'd rather not have to split the block to check the mains. What do you think? Can I expect good mains at 165k? After the engine is done, I will move on to the suspension.

My records start in 2004, therefore nearly 20 years worth. In that time I have receipts for 2 coolant changes and two TB/WP jobs in between, so presumably 4 full or partial changes in that time period. There may have been some undocumented coolant changes as well with references to "Vehicle serviced" as well but I am going to assume there have not been until the heads come off and the full story is known. I do know that's skirting the outside limit on what we now know is acceptable. So my expectations are rather low for no head cancer. The PO documented every tire, windshield wiper and brake pad he put on the car so who knows. It's a massive project and I hope to live long enough to see it done! My son thinks I'm crazy for starting this project at my age (76). But I tell him he's going to end up with this car and he'll have me to thank for every mile he will put on it.
By maddog2020
#209062
once you get the heads off, you will know what they look like, as well as the bores. with the heads off you can get a really good reading on the crank movement to get an idea on the main bearings. Typically the thrust surface and the front main bearing show the most wear. These blocks are incredibly robust, and if you end up having to split the block, you can save half the cost of the main bearing set by buying the glyco 944 main bearing set and the 928 thrust bearing. toss the 944 thrust bearing as you wont need it.
By Stepson
#209140
Nice tip Maddog!

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