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[larso]

Ok, so I stumbled upon a really nice, fascinating trick that has helped me diagnose.

1. Took off boot from air filter box to distrib housing.
2.I was pouring slowly, a few drips of water right onto the fuel meter plate, while engine idling.

3. Engine to sucks in water. Nice and slow though, so it doesn't stall...

4. After a few moments, water starts dripping out the aluminum air intake pipe, that connects to the turbo...the one that has that oring in it.

Diagnosis: now I know I have a vacuum leak..water showed up, so there must be a leak! Easy, safe, and fun way to test for a problem...no guess work with spraying carb cleaner..which is also dangerous.

5. Also, I notice that my engine "clacking" disappears...while I am pouring water into the engine.The engine goes from being CLACK CLACK (not sexy) to being smooth as a cat purring, just by pouring water.

Diagnosis: Either the bypass valve is sucking water in, and trapping some in there to lubricate it..stopping the clacking,

Or: I have some sort of pinging, and the water is helping...can anyone tell me what pinging actually sounds like? I hear a clack clack, not a clunk, not a knock..its a clack, or really LOUD click click sound.

I used distilled water, and yes I know pouring water into there can destroy the turbo after long use, but then so can rain so it's not a big deal to do it occasionally.


Anyway, if I can't fix my car in the mean time (if I need the car, and can't put it on jacks for a few days), I'm going to spray water in there while driving until I can fix it. Water fixes all my problems. Funny, but honestly all noises disappear like magic. Car runs a little less power but no noises at all. I feel like it's some sort of snake oil, it just solves all the problems...and yet I don't think it's pinging. Richening the mixture has no effect on the clack sound, even richening it up to the point where the engine is smoking black. So I am guessing the water is lubing the bypass valve that can clack?

[Cbass]

ping sounds like a top fuel/funny car at idle...

[bho]

Hi Lars, I thought I'd try to help a fellow canuck.

1. Your water trick is a standard procedure for testing possible vacuum leaks around the intake system. Just spray some water around a suspected gasket and if the problem goes away, you've got your answer. There must have been a huge vacuum leak at your O ring to have water come out with the engine on and intake vacuum present.

2. As for the long term use of water in small quantities in the intake charge, that has also been done for a while. Back in the early 80's when I first got my 931, I discussed upping the output of the car with a fellow who built and raced turbo charged cars. He suggested upping the boost and intercooling. Intercoolers back then were prohibitive and plumbing non tivial. Solution was to do water injection. The water did two things to reduce detonation. It cooled the intake charge and the presence of the water increased the octane of the intake charge. It also did a great job of keeping the combustion chamber clean. I could however only get up to 12lbs of boost before detonation with this setup though. By the way, Buick had used this trick in the late 60's, I believe, on their only turbocharged V6 at that time.

3. With respect to that clacking sound. I would guess that it is coming from the front of the engine. And do you hear it as a rattling sound at idle with one distinct clack on acceleration and one on deceleration. If so, it is probably coming from the popoff valve of the turbo charger. This usually means that the two silicone gaskets on either side of the popoff valve, which cushion the valve, are worn. These can be replaced without removing the turbo.