S2 3B and ABY and RS2 ADU Boost Leak Testing (Draft)

[John.]

If anyone can point me in the right direction here I'm listening ! Car is a 1995 ABY

After checking tailpipe emissions at my friendly MOT station, lambda was roughly 0.7 v , CO was 6%(ish) and HC was high too....... wish I'd got a print-out.

So carried a smoke test and whilst we couldn't locate a boost leak, when I removed the oil cap there was a slight noise, so I'm assuming there's an issue with the crankcase breather system.
I bought a new PCV valve but not fitted it yet, I can suck and blow through the new one exactly like the old one so I'm assuming it's not that?
I've been reading through Dave's (UrS4boy) 1st post and my head's bursting !........but as the crankcase ventilation system is mechanical I'm hoping I can get my head around it! ........ the non return valve, on the ABY is this located beneath the idle air valve ?

Thanks, over and out.

[Tractor Dave]

I would replace both the non return valve and the by pass valve. The non return valve is well hidden inside the pipework so not obvious when you look for it, but yes under the intake. The rubber pipe that holds it is also quite fragile.

[John.]

I would replace both the non return valve and the by pass valve. The non return valve is well hidden inside the pipework so not obvious when you look for it, but yes under the intake. The rubber pipe that holds it is also quite fragile.

Thanks Dave, hopefully get to the non-return-valve over the weekend. Hoping TPS can sort me out with the bits?

[Fat Audi 80]

Another leak question:

I have spent many hours with a compressor hooked up to my intake system and have found a few small leaks in various places that I have fixed.

Currently the situation is this:

The car holds 1bar pressure for about 30 - 40 seconds before dropping to about 0.7 bar when my compressor kicks in to re pressurise. First off all, does that sound correct, my assumption is that a healthy car will just hold pressure for minutes or longer?

Assuming I do have a leak, what next?

I can "hear" a leak but cannot find it. I have narrowed it down to between the MAF inlet and the turbo outlet. (Breather to inlet manifold is blocked)

I have sprayed soapy water everywhere and cannot see a leak, yet I can "hear" a slow whooshing leaking sound if I put my ear to the lower turbo hose.

It is possible the the turbo is leaking internally through to the hotside??? Is this something that happens?

Any other opinons?

Thanks

Steve

[Tractor Dave]

I bought one of the cheap smoke machines recently and its made the whole process so easy. I think i posted some pics on my Rs2 project thread.

[newsh]

Another leak question:

I have spent many hours with a compressor hooked up to my intake system and have found a few small leaks in various places that I have fixed.

Currently the situation is this:

The car holds 1bar pressure for about 30 - 40 seconds before dropping to about 0.7 bar when my compressor kicks in to re pressurise. First off all, does that sound correct, my assumption is that a healthy car will just hold pressure for minutes or longer?

Assuming I do have a leak, what next?

I can "hear" a leak but cannot find it. I have narrowed it down to between the MAF inlet and the turbo outlet. (Breather to inlet manifold is blocked)

I have sprayed soapy water everywhere and cannot see a leak, yet I can "hear" a slow whooshing leaking sound if I put my ear to the lower turbo hose.

It is possible the the turbo is leaking internally through to the hotside??? Is this something that happens?

Any other opinons?

Thanks

Steve

He Steve
Yes the turbo can leak past the bearing seals, it would then go through the oil drain pipe to the sump and/or out the hot side.
Have you tested the DV for a leaky diaphragm? That would be leaking back to the IM up the vac line.
I once had a small leak under the clamp on the cold side outlet, had to take the hose off to find it, are you on rubber hoses or silicone?

BTW 40 secs is not bad IME..