MFilippello

iTrader: (2)

How common is it for wastegates to leak from around the valve stem seal area. I have an exaust leak and tracked it down to my turbosmart 48mm wastegate. It is not leaking at the vbands, but where the valve stem exits the 1st chamber. there is a seal there but air comes out. I have gone over the exhaust inch by inch and have eliminated all leaks except this one.

Here is what is going on. While driving, I can definately here an exhaust leak. I put the car on the lift and after it cools down, I run a shop vac in reverse, and stick the hose in the tail pipe. I then go to every joint with some soapy water and check for leaks. I had a bunch. I took the entire system apart and bench sanded every surface from the manifold back. the exhaust manifold was warped and leaking at the block. it was leaking at the turbo. It was leaking at the vband. You get the idea. After spending a whole day putting everything back together, the only place where air is coming out is at this valve stem.

My wastegate is routed back into my exhaust. By pumping air in from the rear I am pushing air into the backside of the wastegate valve. The side with the valve stem. In normal function, the exhaust would hit the front face of the valve and stop. Unless I am pushing enough boost to open it. I am breaking in the motor so no boost for me. The air in the downpipe is going out and flows past the hole where the wastegate dumps back into the exhaust. I would think this would create suction on the dump return but who knows.

Anyway this is the only place air comes out and I do not know if that is normal. Putting a shop vac in my tailpipe is not normal so I do not know if this is a valid test. I definatey still hear a leak.

Mike

GUITARJUNKIE28

good idea with the shop vac! use a dj fog machine with that and no leak will be safe!!

if you're leaking from the valve, the valve probably isn't seated.
my guess is if it's bad enough to hear when you're cruising, it's maybe warped or something.

if it's just a teeeny tiny leak, you can take the wastegate apart and use lapping compound to reseat the valve. (yea, same exact way as lapping the valves on pappi's chevy engine)

RacerXtreme7

iTrader: (2)

It sounds like he's describing the leak from the valve stem area were it goes into the head portion of the gate like a valve guide type of thing rather then the actual valve seat. Sorry I'm no help (I don't know if the Turbo Smart are supposed to be sealed here or not), but I wanted to clarify this for others who might be reading so to get the proper answers for this guy.

~Mike.............

MFilippello

iTrader: (2)

This is exactly correct. the air is coming out where the stem passes into the main housing. The other end goes up to the diaphram side.

Mike

GUITARJUNKIE28

oh... that's a vacuum leak then. not an exhaust leak.

pop off the top and make sure the diaphragm isn't pinched or torn. good thing you found that before you started boosting. that was a boom waiting to happen!