8 cylinder front engine iconic vehicle
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By captainOCD
Yes, there are parts lists out there, but I figured I'd both bring some more content here and get some answers to some questions I have at the same time.

Anyway, my intake sure seems like it could use some attention. The car runs fine (at least as far as someone that's only driven this 928 can tell), but there is certainly some oil leaking into the valley and all over the throttle body.

The intake just looks plain ratty at this point too.

I certainly will be replacing the intake gaskets. I already have paper ones that someone gave me, but I think based on serial number my car might have the metal ones. Are the metal ones really worth the $300-$400?

I want to replace all of the rubber sleeves and orings joining up the different parts of the intake system too. They're old, cracked, and nasty looking. Replacing things like the small vacuum lines makes sense too.

Not sure if the ISV or TPS should just be changed or left alone if not seeming to give problems. Sounds like the TPS can be tested, but not sure if that's true of the ISV. Idle seems to be stable at around 800-900 rpm for what it's worth.

What I'm hoping to find out though is do you really need to get things like original molded pcv hoses? This car isn't an all original/concourse winning/etc vehicle. It's a high mileage driver. So if I can just use normal vacuum hose for stuff like that rather than $50 per hose to go from the cam cover to the intake, I'd rather go that route.

While the intake is off, I'll of course repaint it. I'd also like to replace the cam cover gaskets and inspect the timing chains and tensioner pads.

So far these are the parts I'm planning to get. Hopefully someone can help me fill in the blanks.
paper intake gaskets (have already) - 928.110.568.00
8 small runner seals - 928.110.343.00
2 large runner/"T" seals - 928.110.347.00
large maf oring - 999.701.699.40
small maf oring - 999.701.183.50
maf sleeve - 928.110.243.02
throttle body oring - 999.701.436.40
throttle body sleeve - 928.110.248.03
8 sets injector seals - 944.110.901.00
vacuum hoses and elbows I'm hoping can be off the shelf parts unless they must be molded to locate things or something

2 cam cover gaskets - 928.104.447.06
8 cam cover orings - 999.701.731.40
26 cam cover bolt seals (not sure if these are correct) - 928.104.115.02

So what does everyone think? You can tell me I'm an idiot if I am.
By captainOCD
I should add water bridge seals and oil filler seals to the list too. Figure I may as well change those as they may be seeping some. I'm also interested in adding some baffles to the filler neck and cam covers. Seems like the current ventilation system sucks too much oil into the intake.
By Addlight
Here is a write up I did for when I did my 86.5 intake:

With the help of a half-dozen other Rocky Mountain Sharksters, a lot of beer, some brats, chips, fresh homemade cookies, watermelon, sodas and water, we did a true and complete intake R&R on my car yesterday.

Here is what my problems were: rough running that I thought may be from vacuum leaks and at least one cylinder not firing from what I figured was a bad or clogged injector. This is a long-dormant car to which I had already: done TB and WP, new plugs, wires, rebuilt MAF, installed new coils, cleaned grounds, installed new filters and drained old gas.

I replaced everything I could think of that needed replacing to make the car go fast. I did replace every rubber hose, every vacuum line and connector, injectors, gaskets, ISV, boot, rubber stand and sensor (except TPS, which I should have).

When I got all my parts, I printed out the corresponding pages in the PET for air box, vacuum, oil system, coolant system and intake system and marked on the drawings where each part I received went on the diagram by matching the P/Ns to the PET. This is pretty valuable because many boots, O-rings and hoses look similar to the untrained eye.

I started five days earlier with the disassembly. It seems daunting at first, but actually only took about five hours total over three nights to get everything but the water bridge and oil filler neck off. What was removed, in approximate order, was:
- strut bar across engine bay
- intake tubes and airbox, taking care to be gentle with the connector for the intake sensor mounted on the bottom
- MAF - again, gentle with the connector
- intake wings. I then shop-vacced everywhere I could get to
- center intake tube (the big diameter T that feeds out to the wings). I used a long screwdriver to undo the clamp holding it to the throttle body
- fuel injector rails. I used a Ziploc baggy held under the connectors to collect the fuel. I worked the rails so the injectors came out with them - I plugged the injector holes with used rubber gloves. I then Shopvacced as much crud as I could get to.
- intake tubes, at which time I found one with a gasket, one without - I removed the rubber gloves and stuffed rags into the intakes.

I use a grabber to hold the pins when I disconnect the sensors and injectors. I still lost one pin.

At this stage, the hideous filth of the valley is mostly revealed. It's not that filthy. But mine was home to many mice who enjoyed two things: eating acorns and crapping. Lots of acorn shells and, well, crap were found. I was lucky, the valley was largely dry and not too oily.

The Shop-vac was used to suck up as much crud as possible. I think it is extremely important to vac frequently throughout this process because even with rags in the intake ports they are vulnerable to debris, tiny clips, nuts, washers and earrings. You know, like if your wife comes out and is so fascinated by what you're doing that she has to take a close-up look. I also photographed parts before I removed any hose or vacuum line, and if I could, reconnected then after removing parts, just for later reference.

Removing the throttle body and air guide is straightforward. Four bolts hold the body to the guide. Three rubber stands with bolts top and bottom hold the guide down. Two of mine were split, but I had replacements for both. The old ones were removed by using a Dremel and cutting wheel to cut off an edge so they were easier to unscrew from the block.

In case you find a split rubber stand and have no replacement: they are the same P/N as the rubber bumpers that support the airbox, so you can use one of those in a pinch. At least those are easier to get to to put replacements on.

Once it's off, I used a screwdriver, putty knife, lots of engine cleaner and Simple Green to get off the hardened crud, oil, dirt and corroded magnesium off the block. A toothbrush and larger scrubbing brush came in handy, as did loads of paper towels.

Putting it all back together takes longer because of cleaning and the assembly of new parts.

Saturday, the rest of the crew came over, led by Stan (mrmerlin). I told people we'd start at 10, so he was there at 8:30. That was fine with me, and a real mark of dedication on his part. And, by the way, his perlglanz car is absolutely gorgeous.

Saturday morning we removed the oil filler. I had purchased a gasket, but it turns out the car needs an integrated baffle/gasket. It's a steel plate with the rubber gasket mounted in it. Make sure you get the right part for this. We used the old baffle with a coating of silicone grease along the old gasket and some high-temp RTV gasket maker on the other side.

We got busy building all new fuel lines using Roger's kit. It is all the clamps, enough EFI hose and one OEM hose with the correct fittings to redo all your fuel lines. Most of the old lines have the schwage as has been discussed here before, and you will cut your fingers peeling them off. Stan cut the schwages with a dremel and I removed them with wire cutters. I then used a razor blade to cut the old lines enough to pull them off the barbs.

Making the new ones, Stan told me to push them directly on, using spit as the lube. Twisting them on can weaken the hose. We did not tighten the clamps onto the hose, waiting until they were on the motor so we could orient them correctly.

We also used engine cleaner, Simple Green and BrakeKleen to clean fuel-rails, intake tubes and the intake wings as much as possible. Then rinsed them and left them in the sun to dry until we needed them. Oh, and we had plenty of sun, since it was about 97 degrees outside.

As others arrived, Stan directed them to various tasks, such as greasing the new injectors and fitting new rubber hoses. I bought a set of new Ford Motorsport blue top 24# injectors. They are a direct fit. You do not need to swap the O-rings for the 85-86 cars.

Under the air guide and throttle body is the heart of the vacuum system: the seven-way splitter. This runs off the back of the throttle body in a single line which feeds to the seven-way and out to a bunch of systems I may never fully understand. I'll get to it that after I understand quarks and neutrinos. Well, mice chewed a big hold right through my seven-way, so I didn't have vacuum to any system.

Things were reinstalled in the following order:
- fuel lines
- oil filler neck
- thermostat housing with thermostat inspected and cleaned
- vacuum lines routed, although not all can be fully connected until the intake is in place.
- air guide rubber stands and the air guide
- throttle body, then TPS and throttle were adjusted to trigger the TPS at WOT (mine was not clicking before adjustment)
- hoses, hoses and more hoses - oil breathers, air and others whose jobs I can't remember - at this point you may need to temporarily disconnect other parts to fit the hoses
- intake gaskets (dry) - I used paper ones specced for an 85 because they cost 1/10th what the metal/rubber 86 ones cost
- intake pipes
- coolant temp sensor
- airbox sensor
- fuel injectors - placed in rails and then fitted as units to either side - use some pressure to get them seated.
- intake wings

Throughout the process, Stan made sure everything was either greased or anti-seized. Take the time to do this.

We did not put the air box back on so we could watch the fuel lines and injectors when we cranked the car to look for leaks. We had a fire extinguisher handy and the car was on rollers so--if there was a problem--we could shove it out onto the lawn next to my rusted-out Nova up on blocks and the old fridge we let my son play in. While Stan cranked fuel pressure up, two of us stood with lights on the engine, one with the extinguisher and the rest with their hands on the front bumper ready to roll it.

It cranked, cranked and cranked and then vrrrrroooooom. Rock steady and beautiful idle. No leaks. Since I have had this car, I have had moments of smooth idle but they never lasted long. And it was never as smooth as this. Everyone had to take a turn goosing it and listening to the instantaneous and smooth response.

I was just about jumping out of my skin with joy. When you have problems like a rough idle, your mind always wanders to the worst-case scenario and every little smell your car makes is cause for worry. But finally hearing it so healthy lifted a huge amount of worry off my brow. Hearing six other owners say, "That sounds great" and Stan say "That sounds so hot!" is very reassuring.

We watched for leaks of any kind and saw nothing. The temp gauge went to halfway and sat there, nice and steady. No warning lights. The torque tube started to whine, which is new, and the driver side exhaust manifold leaked. That I knew about and have an X-pipe to put on there as soon as I can Sawz-All off the old, rusty bolts.

Then, we drank beer until it was all gone.

If I had to do this myself, I would guess 15 hours to clean, build, replace. With the gang there, it was a solid 7 hours with a break for lunch, but it was done much better and all those extra eyes and expertise are hugely valuable when dealing with vacuum line routing, which piece to put in before which and all the BTDT experiences.

By captainOCD
Thanks, definitely a lot of detail there. Sounds like it was a fun day too.
By Addlight
One more thing to add: I would splurge on a vacuum kit, unless you feel comfortable that you can source all the splitters and elbows and have every hose the right length. There are many, many hoses and connectors, and the connectors need to be the right type of rubber to withstand underhood temps. The first kit I bought from another 928er was made up of medical grade rubber and degraded fast. Our vendors will steer you straight.

To me, the peace of mind and the savings in time of having the right parts will outweigh the cost savings. I got mine from Roger (this was a while ago)
By Addlight
Thinking about this some more, here a few suggestions/thoughts. When I did mine, I did a full top-end refresh, but that isn't necessary if your engine is in good shape, so:

- paper gaskets have been fine for me. The intake job is simple enough that I think you can use them and go back in if you have an issue. I installed mine dry and have had no issues. Just make sure you clean the intake and block surfaces really well. Don't push a razor blade over them to remove old crud, but drag it so you don't nick the surfaces.

- Definitely replace all the rubber intake connectors (8 small/2 large). These things basically soak in oil and crumble. I typically look at them every year and replace the rotten ones every couple of years. The two large ones seem to go first. If a ring is in decent shape, I treat it with silicone dressing or DC111 and hope they stay pliant. Not a bad idea to keep the best ones you pull off in reserve. Also, when putting it back together, make sure the runners are seated and the clamps are a tiny bit tighter than you think they should be because these things are where I have experienced air leaks.

- If you paint the intake, really, really degrease the heck out of it and even run some sandpaper or a wire wheel over it to get the flakes off. Use an engine or brake temp paint. Most people powder coat but I think you can get a decent result with paint and a load of prep.

- ISV and TPS - they don't need replacing if they are working fine, and if you already have a steady idle, the ISV probably is. There are good writeups on testing and adjusting the TPS.

- Be prepared for a lot of brittle plastic and rubber under the intake, such as the stands. Just take your time with it and be very gentle. Also, be prepared to get halfway through the job and realize you need to order another part or a few. So, do the work where you can leave the car sitting for a few days.

- It is a lot of work to clean as you go, but really rewarding to see everything coming back to its original glory. Plan for it to take some time and have plenty of solvents on hand.

- As for hoses, get the right ones. If you cut and fit your own, the bends may crimp and restrict or you may find you cut yours just a hair too short or too long and they don't fit. Or, your bends are where they shouldn't be and the hoses rub. If you're doing the fuel lines (which you should if they've never been done), get Roger's. New hoses that fit will give you peace of mind that far outweighs the cost.

- Treat your two intake tubes like gold. In my experience, they are the most unobtainable items under the hood.

- Finally, expect everything to be connected by one more bolt than you expected and that bolt will be the hardest to get to. So, be gentle pulling things apart.

By linderpat
Great stuff so far. Another thing, take lots and lots of pictures from every angle under the sun(hood). You cannot have enough reference pictures. Take them before you start taking things apart, than as you go. Every angle and multiple shots. You will be happy later.
By worf
There's an extension harness from the Idle/WOT switch (a.k.a. TPS) to the LH engine harness.

Chances are that the connector bodies on the extension harness are dust. Last time I looked the extension harness was NLA. I made a new one with connector bodies from eagleday.

Idle/WOT switch is easy to test with a multimeter. LH/EZF troubleshooting guide details how to test it at the ECU pins. Or you can test at the switch (or extension harness.) It's two simple open/closed circuits. One pin for idle, one for WOT, one for ground. IIRC ground is middle.
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By Landseer
Roger had been remaking that extension harness, he might still stock it.

Replace the three rubber standoffs that have the treaded mounts. 3 under throttle body, 2 others supporting air box. Careful there are 3 sizes amongst the 5 needed.

Can you post a close up pic here please of your car's cam cover bolt heads? There are at least two versions. Some have o ring and a flat washer style rubber gasket, some dont have that gasket. Am told the S4 style is on piece bolt, safe and simple. I think they are exposed allen heads?

The two piece cam cover bolts can be diabolical. My 86.5 had same as my 2 86 and 85 cars ... two piece standoff style cam cover bolts. The exposed heads are 13mm. But beneath the cover they have necked them down to tiny male threads that in turn screw into standoffs. The standoffs have tiny threads that in turn screw into the heads. You haven't lived til you've had the standoffs shear off in the head. Not sure if the better bolt removal tactic is slow pull or impact. But the extraction process if sheared took me 12 hours. It can become a very difficult extraction .
By Geza-aka-Zombo
Not sure if you know of this, but 928 Specialists has an intake refresh kit that lists relevant parts.

When it comes to repainting, I'll do a little write-up of what I did for mine. It came out great, seems to be holding up (been over a year now) and is fully DYI.


By SeanR
Roger does have the TPS harnesses in stock, I made a bunch more last Friday.
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By captainOCD
Looks like I've got the allen head bolts for the cam cover with rubber washers under them as far as I can tell.

Is this the TPS harness coming up to the front of the motor? Mine has been disintegrated since I got the car. I heat shrink wrapped each terminal (the part not making contact of course) so they wouldn't short out, then taped up the connection so it wouldn't get wet. Either way whatever that connection is, the connector is hosed.

Sounds like the molded hoses under the intake are a good idea then. As for the TPS I guess I'll test it when I get things apart. Not sure the ISV can be inspected for proper function or not.

I'll be working on the car in the garage, so it can sit if need be if I need to order more parts. I just hate to spend money on parts that still have plenty of life left in them.

As far as painting the intake, I've read enough horror stories about left over powder to not want to mess with that. I'd rather just clean up the old paint, find something that is fairly close to the original color (if not, probably silver), and fog it. May use some of the enamel paint I have left over from doing valve covers on my Durango and paint the lettering black or something.

I did see the intake page from 928 specialists. Everything seemed reasonable there, just that some of those molded hoses were $50 - $130 in some cases. That's what prompted me to wonder if some of those hoses could be substituted with some generic hose. Also looks like Roger has an intake kit, but it's listed at $1900 and doesn't list out what's included on the site. Guess I'll have to call him to see what all is included there.

It's just when you look at some hoses like this 928.110.673.00 you just can't help but thing that it's not that special looking and there has got to be something similar out there that isn't $130.
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By Landseer
Always buy the molded hoses. The majority have multiple diameter ends. Cobbled just plain looks bush league.

That said, one of them, the rear most cam cover vent hose.... And it might be the one you pictured,....was discontinued the last couple of times I bought parts. But roger sells a suitable semi professionally pre cobbled substitute that doesnt look too bad.

That TPS test port wire that Sean produces looks great. The TPS itself is interesting. Roger identified that they have a weakness and crack at solder joints. Plus they fill with oil. If you reuse, consider separating the case, rinsing with solvent and reassemble. Remember you need the mounting o ring in either case. Else risk vac leakage. Also, butterfly shaft bearings and seals can clean up vac leaks.
By worf
Landseer wrote: Mon Apr 05, 2021 1:33 pm Plus [the TPSs] fill with oil.
If the Idle/WOT switch is filled with oil then two things are called for:
- replace bearings on throttle plate spindle with 2RS versions
- deal with the oil ingestion issue.

Solutions for the latter in S4 Land are well known and documented. Likely the same basic solutions will work for an S3:
- remove plastic air/oil seperator(s) from under cam covers (these are really just vacuum nozzles for aerated oil) and replace with baffle plates.
- additional oil filler neck baffle
- additional crank case breathing (vent the other cam cover)

I don't recall seeing a ProVent setup for the organ pipe motors, but I'll bet they are out there.
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