Where did my boost go?

[timcarson]

My 1986 911 turbo has plenty of boost when the motor is cool, but when it reaches operating temperature it quits making boost. I've replaced the silicone o-rings and rubber sleeves along the boost plumbing path, but it made no difference.
Has anybody heard of this problem or have any thoughts as to what I might check in order to fix this problem?
Thanks.
TC.

[Ronnie's.930]

One possibility is that the wastegate valve is sticking open when the wastegate heats up (this might be a longshot, however). The next time this happens, maybe you can run the car in neutral and check to see if exhaust gas it coming out of the wategate muffler (or straight pipe if you have replaced the OEM muffler) when parked and in neutral.

[gsxrken]

Another way to Dx the waste gate would be to pull the hose that goes to it from the intercooler and see if it still boosts when you get it hot.
This is also a good way to over boost and cause detonation > broken rings, so be smart about it.

And with these cars it's always good to check your fuel pressures with a CIS gauge kit when something is screwy.

[timcarson]

Thanks, I'll try your suggestion.

[Miguel Antonett]

First post here... Welcome!!!

Pictures of the car are imperative to continue the dialogue.

Heat sink is always an issue with our cars.

[T77911S]

WG.
more than likely the valve guide is worn out.
get a tial form himniracing.com

i pulled my WG and put about various amounts of air pressure into to test its opening pressure. i could hear and feel the air coming out of the pipe with it closed