rufrob

Happy New Year and all the best for 2017.
I am reviving my 86-951. I worked on in a lot 1 year ago, but I has been sitting idle since then.
Over the holidays I gave it a fresh coat of paint and worked on the interior. I noticed it wasnt boosting as it did before.
I tried the wastegate test as set out on Clarkes Garage, but I dont understand something. I start the car, the crossover pipe and turbo pipe warms up but the wastegate stayed cold. I applied the maximum vacuum and it holds pressure but the wastegate remained cold. What am I missing? I thought if the wastgate is closed then it should boost, open and no boost.

rlm328

The waste gate is to relief excess pressure by by-passing the hot exhaust gasses. If it is not boosting does not by-pass the exhaust so it does not get hot. When these things don't boost the first things you should eliminate are vacuum line leaks and bad IC pipe connections.

I would try these first.

Jherriott

Isn't the wastegate open very slightly at idle and part throttle so the engine isn't losing efficiency pushing exhaust past the turbo? Maybe you have your vacuum lines crossed? Also I would check and recheck all your vacuum lines for leaks. Easiest way to do this is buy a vacuum line set from Lindsey in a new color and go through and replace them all.

If you are running your original wastegate, it's highly likely your springs have weakened or even broken, bleeding boost. But then your wastegate would be hot after a good run.

NCLA951

I sure hope the wastegate is not open at idle or part throttle! The bypass valve may be open at idle due to vacuum, my forge hisses at idle, but the wastegate should be closed until preferably the boost controller tells it to open, or with an old factory WG when the spring is overcome by exhaust back pressure.

GPA951s

E-Z waste-gate test= Vice grips on the hose going to it, after the cycling valve. Hit it once and it will take off like a rocket, then I would suspect its the cycling valve itself. The valve sees 12V after 1/2 throttle, when I tested one , I made a T connector for the plug, ran wires up though the hood into the driver compartment, and I tie wrapped a mulit-meter to the dash. I always had 12 v after 1/2 throttle but intermittent boost. take the valve out, put 12 v to it and make sure the ports "switch", you will hear the valve "click" as well. That is the biggest failure point, its plastic and sits on top of the hot motor and under a hot intake..so its dutch door action as far as heat goes.. I always carry a spare to the track when I go, they really can't take a joke.

Luis de Prat

Check the blow-off valve. It may be stuck.

rufrob

Thanks for the advice. I'll check for vacuum leaks first. Turns out I have a cam cover leak, again!