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Old 09-23-2013, 06:37 PM   #38
Board Member
Join Date: Jan 2007
Location: Vero Beach

Nope, this thread still isn't dead yet. Miraculously, the car isn't either.

I finally have some time to work on the stupid car again. I've been driving it around and it seems to have settled into a reliable, if slow and boring, mode of operation. Pathetic attempts at boost when cold, getting less punchy as it warms up. Otherwise runs rock solid.

After buying a few more pieces for my kit, I have conclusively determined that the leak is either in the turbo housing itself or the wastegate actuator. I am leaning towards the actuator but before I go buying parts I want to check that I'm not crazy.

(Just for reference, the way I determined this was by applying a pressure plug to the turbo outlet and pressurizing the intake as normal. Pressure will not build in this configuration unless I hold the air compressor valve open. I did a similar test to rule out the intercooler with a perfect result - it held pressure north of 20 psi.) I can hear air leaking somewhere but I cannot feel air leaking anywhere.

Previously if I tested the wastegate actuator by applying air pressure directly to the signal hose, it would instantly move. However, if I pressurize the turbo from the air inlet, it doesn't start to move until around 30-40 psi! This strikes me as being a big problem. If I happen to be wrong here please let me know, but I think I'm finally on to something given that it's supposed to open at 7-8 psi stock.

If it ever stops raining (not going to risk my life on jackstands on a sloped, wet driveway), I am going to pull the actuator out, check the wastegate arm for smooth operation, and check for a blown gasket. Assuming I find a smoking gun in there, any recommendations for a Garrett T3 wastegate actuator? I don't mind spending a bit extra for something I can use for years. Current plans are to keep the car at ~12 psi until I can swap the M46 for something less likely to explode, so something adjustable would be nice but not necessary right away. I keep seeing references to a Forge unit but their website doesn't have one specifically for the T3, so it's probably a crossover and I have no idea which variant would be the right one - advice would be awesome!

Thanks again guys. With any luck I can FINALLY put this stupid project to rest and focus on something more fun.
AdmiralSenn is offline   Reply With Quote