Greddy T78/88 Boost Creep Fix

**Kirk** · 11-14-2007, 03:59 PM

You will notice that the wastegate has 8 allen head screws that tighten down to compress the spring.

These screws also tighten down on the wastegate diaphram to make a seal.

Under that you will find 3 larger diameter allen bolts that connect the lower aluminum wastegate base to the cast metal housing.

Between these 2 pieces there is a seal.

My seal was leaking preventing the wastegate plunger from being raised enough to regulate boost.

I unfortunately didn't have a new seal so I made one out of universal gasket material and it worked great.

Also be sure to use blue loctite on the threads of the 3 larger allen heads bolts or air WILL leak out of the threads (I learned that the hard way).

I also recomend while you have the gate apart to clean all the carbon and oxidation off of the plunger and associated parts with some 1000 grit sand paper or a scotch brite pad.

Also use some antiseize on the plunger shaft.

Before reinstalling the gate I also suggest puting around 15psi of pressure on the side port and spray the gate with soapy water.

If there is still a leak it will bubble the soapy water.

I was always afraid to take my gate apart in fear that I would not be able to compress the spring again.

It is a little tough but anyone can do it especially if you have a second person helping.