951mat

My 86 951 is not boosting correctly. It makes about 1.2 bar on the dash gauge. Runs smooth, just no power. I don't think its the wastegate, I clamped the line going to the top and it does the same thing. Cycling valve is new and make a bunch of noise w/ battery voltage hooked to it. I've replaced almost all the vacume lines I can also. Here's the strange part. I cut a fuel filter in half and put a tire valve stem in the end, clamped it inside the intake boot going into the turbo, and pressured up to listen for leaks. This is a procedure in the manual. I have air coming out of the oil dipstick tube! Can someone explain this to me? Is this my problem?

Rob

It's not your problem. The intake boot where you clamped the half filter into has a large hose that goes from the boot to the air/oil seperator. This line provides positive crankcase ventilation, since this boot connects to the intake side of the turbo and normally only experiences a small vacuum pressure. This means that when you are pressurizing it, you are also pressurizing your crankcase. So, whenever I pressurize the intake tract to look for air leaks, I disconnect this hose from the boot and plug the hole. This way I am not pressurizing the crankcase and all it's associated seals.

Good luck with your search.

Rob

Dal Heger

Wait a minute. You clamped which line? The one going to the wastegate? If you clamped the one going to the wastegate to test the wastegate and it still only boosted to 1.2 on the gauge, then it's the wastegate. With that line clamped, you should see the turbo spooling and producing boost much higher than 1.2 bar (actually, you should overboost and hit the overbost protection - take the foot off the throttle before you blow the engine up!).
When you replaced the CV, did you make sure that all the lines were hooked up correctly?
Did you test/replace the bypass valve (the one connecting the intercooler to throttlebody pipe to the intake boot (to the turbo)? It could be that you're boosting correctly, just that bypass valve is busted and recirculating air into the turbo intake again. If you can blow through any of the holes in that bypass valve it's toast! Get a new one (make sure to get the 993.xxx.xxx.xx part number).

Good luck!

Dal.

951mat

I know I hooked up all the lines correctly to the cycling valve, and yes my bypass valve is new. I agree that with the line pluged to the wastegate it points to a wastegate prob. I swapped out my for my friends spare and it made no difference, granted his spare used one could have been bad too. According to the manual it could also be intake leaks, exhaust problems, turbo problems, or KLR. Still looking. Thanks.

Perry 951

If the wastegate is stuck open, there is an easy quick test to check.

Start the car cold, and get under the car. Put your hand on the bypass outlet pipe. If it begins to warm up within a few minutes, then the wastegate is bad. If it stays cold and the rest of the exhaust is hot, you are ok.

951mat

I did the wastegate check and it isn't stuck open. It doesn't heat up just idling. I did notice that my wastegate and my friends that I borrowed both have 2-3 small cracks in the valve seat. Could this definately be my problem, I thinking it may be. I shimmed one of the wastegates w/ 2 washers and noticed a .2 bar increase. I put on 2 more washers and it didn't help noticably. Has anyone noticed that they have cracks in the valve seat but still make good boost pressures?