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We have had some of these on NordicAudi, just like yours where the valve guide is worn and in some cases the valve shaft too.
Any mechanical work shop should be able to machine a new one for you.
5/100 millimeter play between the shaft and the guide has proved to work just fine.
Yep , there will always be leakage around the stem of the WG valve. Also be careful with applying pressure before the turbo. People have blown oil seals in the turbo due to no counter pressure at the exhaust side. Best thing is to pressure test from the hose that goes to the IC.
1995 RS2 on Alcohol (6.8sec 100-200km/h)
1994 80E Avant
1986 2L Golf 2 on Alcohol
Don't know if you Paul and Espen is referring to me but, I for one has never said that that the guide and the valve stem can create an airtight seal.
That's just not possible.
I was just implying that if all other faults has been written off then it could be the WG valve being stuck open dumping boost, if it has too much play in the guide.
This is a at least in Sweden a well known fact.
Agreed if WG valve is stuck open - or the guide is massively worn then problems can result.
Also agree with Espen - boost leak test is best performed from hose that attaches to output side of compressor.
The MAF hose and compressor inlet is not expecting pressurised air at that point - they suck - and consequently you get air forced past the oil seal in the turbo cos its just not designed for that. Might be airtight on a freshly built turbo.
The hose system needs to be airtight from turbo outlet thru the intercooler to throttle body.
A leak in the MAF hose will cause unmetered air on vacuum.
Also look carefully at the ISV hoses near the throttle body - a leak on those causes unmetered air on vacuum and loss of pressure under boost.
Finally check the PCV hoses properly for leaks... possible source of unmetered air as well.
've just been applying pressure to the pipe feed to the wastegate diaphram. So nothing else is getting pressurised. I started buy pressure testing the whole system and found the leak to be in the WG. At least thats where it could be heard leaking from.
The pressure does not hold at all not even for a second and can be heard leaking out. No visable split in the diaphram.
I have mm's of play in the valve in its guide, surely thats not normal?
've just been applying pressure to the pipe feed to the wastegate diaphram. So nothing else is getting pressurised. I started buy pressure testing the whole system and found the leak to be in the WG. At least thats where it could be heard leaking from.
The pressure does not hold at all not even for a second and can be heard leaking out. No visable split in the diaphram.
I have mm's of play in the valve in its guide, surely thats not normal?
Sounds excessive
1995 RS2 on Alcohol (6.8sec 100-200km/h)
1994 80E Avant
1986 2L Golf 2 on Alcohol
I took the wastegate in pieces to Doug at MRC who gave it a clean bill of health and listened to my symptoms. He suggested my timing was out and explained to me where it should be and that a certain place who had adjusted it often adjusted it wrong.
I have to say that I was suprised to hear that my timing was out after I ha changed belt as I was very careful to check it many times and marked it all up with old belt etc.
So I moved my timing back to how I had it and rebuilt wastegate and refitted etc. I also stripped every boost hose off. Cleaned, inspected and refitted all bosst hoses etc.
Also in a moment of clarity the other night I suddenly wondered if my dump valve was on teh right way round. A random thought but as i'd never taken it off, and the boost system had been checked buy the same place as timing changed I had no reason to think anything different.
Either way when I refitted everything I put it back on correctly. Then hey presto full boost and a massive grin!!!!
Many thanks to everyone for your help. Keep up the good advice, i'm sure i'll need some more soon!
yeah one tooth out. I changed belts and got it right but then it was 'put right' whilst car was at specialist being diagnosed for boost problems. Then I put it back to how it was.
Wasn't the only fault the wrongly fitted dump valve etc did'nt help but that was like that from when I bought car so hadn;t spotted it!
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