The internal wastegate on my disco potato is occasionally sticking open.
Its exactly like this guy's:
except it only happens occasionally and it isnt a chinaturbo, its a Garrett.
After pulling the DP and inspecting, it appears its doing exactly what Corky describes in his WG porting guide
as a possible problem created by over-porting the wastegate:
Note that the wastegate valve (flapper door) can move around quite a bit. This freedom of motion causes a problem with enlarging the port. The hole cannot be uniformly larger as the free motion of the valve can cause the edge of the valve closest to the pivot arm to collide with the edge of the hole and jam it open.
Except I don't believe my wastegate is ported (I'm the 3rd owner of this turbo, so I can't be sure)
How can I solve this problem?
My first thought was that if I could make the flapper not quite so loose on the arm, it would solve the problem... maybe putting a circlip or safety wire around the shaft that connects it to the arm to take up some of the slack? Not sure if either of these would survive in there though.