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Hi
I have a 1998 C2 tiptronic with 138 000 km. The car used to idle rough on cold start and i changed the coil packs which eliminated this problem. It now stumbles on idle occasionally. A system scan showed Mass Air Flow Meter out of voltage range so i replaced it and the car seems smoother now. While working on the car i got a friend to pump smoke into the inlet manifold and saw some smoke escape from the large pipe behind the throttle body. There appears to be a fitting of some sort on the pipe and smoke seemed to drift out from here. Any idea how to fix this? Do i need to drop the motor or remove the throttle body? i dont want to make more leaks along the way.
How much pressure was he using?
Smoke machines should have a regulator that prevents more than about 1.5psi.
Depending upon what tool(professional or home-made) he used you may have had too much pressure.
If not, I'd bet there's an o-ring that needs replacing.
I use a home-made smoke machine that uses a propane regulator.
But I've seen people make them and not use a regulator.
That is a pivot point for a resonance flap inside that tube. It should not leak from there, I’ve never heard of anyone trying to take it apart to reseal.
You can remove it without dropping the engine or removing the side intakes, but it’s certainly a pain to get back together properly to avoid leaks.
More commonly, the rubber ring gaskets sealing the center tubes to the sides get damaged or miss positioned and leak all the time. Also, there are several hard plastic vacuum lines that plum into those rubber ring gaskets, which can come out or break, especially with any recent work being performed.
Im just saying, yes you can replace that part with the engine in the car but be certain it’s not coming from a more easily correctable location close to there
Another thing to remember is with a smoke machine you're using positive pressure.
That can force air and smoke out of areas that are better sealed(closed) when there is a vacuum.
It was a very fancy looking professional smoke machine, i will have to check what pressure he used.
Thank you
I wouldn't worry about the pressure then.
It's the poorly made home jobs that you have to worry about.
Every time I get close to buying a professional made one I find other tools or toys to buy.
So far so good. I just smoked the engine again about a week ago and it’s still holding tight.
Unfortunately I can’t say for sure if those in your link are the same. They should work given that they are 3/4” though. Probably worth a shot.
It was the same, after all. I checked it out with the manufacturer part numbers. Anyway, it sealed tight, and guess what? The elbow that you had leak in your aforementioned post leaked in mine! I used the elbow you used with a couple 20mm spring clamps, and it's fixed-- except, now my throttle body is leaking from the dried out gasket/seal. Oh well, 30 dollars to fix three leaks that would cost nearly two grand at a shop (I guess they'd need to pull the intake manifold to get at the resonance tube on a cabriolet like mine).
It was the same, after all. I checked it out with the manufacturer part numbers. Anyway, it sealed tight, and guess what? The elbow that you had leak in your aforementioned post leaked in mine! I used the elbow you used with a couple 20mm spring clamps, and it's fixed-- except, now my throttle body is leaking from the dried out gasket/seal. Oh well, 30 dollars to fix three leaks that would cost nearly two grand at a shop (I guess they'd need to pull the intake manifold to get at the resonance tube on a cabriolet like mine).
01-24-2019, 02:42 PM
Erratic idle - vacuum leak on inlet
