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one other possibility I read on here somewhere was a certain valve between the intake and brake booster. it's basically an almost v shaped check valve. I'll try to find a part number. if this is faulty I suppose this could be the culprit.
and input is much appreciated. thanks
FWIW, that valve is variously called the vacuum suction pump, suction valve, suck valve or suck pump. Audi official name is vacuum suction pump I think. It is not electrical, but they call it that because of its venturi air regulation built into the inside. On my C5 4.2 it was Y shaped and right against firewall. On W12 it was T shaped on directly off one of the intake boots between air box and throttle body on driver's side--twin air boxes on W12. On W12 mine broke open at one point, which caused a big time vacuum leak that was super obvious by sound. I epoxied it while new one was on order.
Ah, yes, it's a Y shape. thank you for clarifying.
OK so update.
I'm almost certain that the gasket for 077109087e cam adjuster is leaking. it is located between the adjuster and block/valve cover. it's either that or the actual valve cover gasket is leaking...
there is a semi circle hole just under the adjuster and if I stick my finger in there best I can, while under pressure, the hissing leak has a noticeable tone change...
Ah, yes, it's a Y shape. thank you for clarifying.
OK so update.
I'm almost certain that the gasket for 077109087e cam adjuster is leaking. it is located between the adjuster and block/valve cover. it's either that or the actual valve cover gasket is leaking...
there is a semi circle hole just under the adjuster and if I stick my finger in there best I can, while under pressure, the hissing leak has a noticeable tone change...
That half moon shaped rubber piece is std. port 4.2 and should definitely not leak--air or oil. See below for a picture of gasket set with the blue colored half moon seal. I just borrowed it from ECS since they have good pictures usually. See: https://www.ecstuning.com/b-victor-r...77198025a~vic/ Victor Reinz is high quality German gasket provider, without having to pay dealer price. Can look at other sets too. If you do the valve cover, which definitely sounds like you should from what you describe, look at both as far as any leaks and likely plan do do both. At that point will make sense to do spark plugs if not recently changed since you are right there and the igniters need to come off anyway.
One thing I don't remember is if you can get that piece out by itself. IIRC it is sort of under the cam connecting chain tensioner, but you can likely loosen just that and then can work it out. What you don't want to back into is having to pull the cams, which then means timing belt has to come off. The seal is there BTW because the two heads are actually interchangeable. When used on reverse side, that opening is where the camshaft would stick out and have the timing belt cam drive gear attached. It's been a long time, but I think one side may have a half moon thing and the other a circular plug the same size as a cam seal would be.
I'm going to pull the valve cover today to get a better look but it appears I don't have a half moon plug installed at all! That's the hole I was sticking my finger in lol. Here's the best picture I could grab with a busted camera lense.
Yep, the problem. Basically on the side with the tensioner that flat surface of the bottom of tensioner fills the top half of the "hole" used for camshaft when head is rotated 180 degrees for opposite side. Then the half moon fills the bottom half. Can't believe someone would have left it out--and then a question why anyone was previously in there that deep for that matter. Hopefully you basically find it sitting inside motor at top of head, though design is such that shouldn't happen and rubber seems very tolerant to any oil or heat effects. Unlikely in my mind it blew out unless the motor has/had serious pressurizing issues from bad PCV valve or other things. You will want to watch for crankcase pressurizing issues with restart, which can be death to not just this seal but really painful ones like main crank seals and upper to lower oil pan seals. As in, step 1, pull motor. Hopefully explainable by something really dumb like someone pushed it in.
I saw some pictures of the heads with the covers off and it seems like there are two positions this half moon seal could sit in - either flush with the face/front and covers the hole we see...or..it possibly could be recessed in there 1/4"-1/2" and leaves what looks like a hole from this angle...
I'm off to buy another t30 bit and try to get this dang valve cover bolt out. It's the lower rear, and starting to be a pain in my lower rear lol
I've paused the tear down until my new gasket sets come in. I'm going to replace the cam tensioner gasket, half moon valley seal, and all the valve cover gaskets...
The only codes popping up now are p0174 and p0430. Bank 2 too lean and bank 2 O2 Sensor. I'm guessing it's air leaking in after the maf, skewing O2 readings.
I doubt it's the intake manifold loose bolt TSB, as I've tightened them all down in proper sequence. Some were tight, some not as much.
Gaskets are here! I made sure to order the valve cover set as well because I'm opening it up. No need to risk the old ones not sealing....and for $66 CAD I got all this. I have an AMAZING vw parts guy....I cannot say enough good things about Dubsport in Edmonton.
nice. Mine were recessed for sure, looking like they were missing, but they were completely hard and probably ready to leak. Hope this helps your leaks
03-23-2017, 06:16 PM
