gtred

I have been slowly picking away at a few issues on a new-to-me100k mile 2001 turbo. Interior and exterior are now very nice. New radiators and all the forward hoses. Engine basic service then a UMW tune.

However, I'm still not seeing the total turbo nirvana as it seems I have a boost leak. When the engine sees .3 bar it quacks like a duck and then gradually builds boost to .6-7 bar. I did a boost leak check blocking off and pressurizing the turbo outlet lines; the system did not hold pressure. There appeared to be air leaking out near the "f" pipe, but as I was doing this alone, it was difficult hold the air chuck under the car and also try to pinpoint the exact failure/breach on the top of the engine.

I'm going to try to lower the engine a bit and perhaps get a friend to help. I guess we'll just remove the diverter valves and see if they hold pressure. Am I on track here? If they are bad, just replace with OEM? OEM "f" tube?

Also, how hard is it to also replace the check valves and other "common failure points".

xmaciek82x

I had about 2" crack in my f-pipe. There had been multiple cases f-pipe cracking. There are various vacuum houses around the DVs that can cause leaks. Instead of replacing parts, try to find the actual leak.

Kevin

Classic Diverter/Bypass valve failure.. Geese honking under engine load>>boost does not build up. Turbochargers are killing themselves as they overspeed to the darkside...

So, to troubleshot this you need to get a MityVac pump and pull vacuum on the top port of each diverter valve. If it is a open blown diaphragm (torn) you would be able to build vacuum.

Please go through this exercise and post your results so that when people use the SEARCH, this thread will show the failure, the trouble shooting and fix.

Order new Kaiser replacement Bosch 710N diverter/bypass valves

gtred

Thank you Kevin. I've been working on fixing the "little things" on this car off/on since the beginning of the year. While I want to get it all done and right, I'm getting a bit impatient lately. I'd really like to get it all buttoned up and drive it soon + test out that UMW tune! Craig

gtred

Diverter valves and f-tube checked out fine. The problem ended up stemming from a vacuum line that blew off (under f tube). Now holding 1.1 bar... hard to imagine how a little leak like that can cause a loss of half a bar....

An additional leak was found in the non-pressurized side... one of the intake hoses behind the motor. This looks to be an engine-out repair and will likely have to wait until I wear out the clutch with my new-found boost.