Wastegate Stuck Open?

[Feadz]

A few days ago I noticed a different sound coming from my car at idle/ no load, at first I thought it was an exhaust leak, so I thought nothing of it. Then I noticed my car would build boost on and off, say I'd do a pull in second gear it would build 10 psi by 3.5k, then the next pull it would hit 1-3psi max.

Specifics: JGS log manifold, JGS400 w/ "Medium Spring ("8-10psi)" , HKS hi-powwwah, and AEM truboost.

-The vacuum/pressure lines to the wastegate are hooked up correctly and was running fine until the noise appeared. Not even 500 miles on this setup.
-The floating valve seat is installed between manifold and wastegate.

First thought was a boost/vacuum leak, so I grabbed my smoke testing machine and ran it through my BOV vacuum line, no smoke/leaks. I hooked up my boost leak tester to my hot pipe and charged the pipes to 20psi and it held steady, which lead me to the wastegate problem.

The initial test: Turn the car on, feel around for exhaust leaks. I didn't feel any exhaust escaping from the exhaust itself, but I did feel some exhaust coming out of the dump tube at idle. From my knowledge the wastegate should be closed on idle, so it shouldn't be venting any exhaust out, correct?

The next test: I turned the car off and I ran the smoke tester through the exhaust, the smoke started pouring out of dump tube, so I plugged the dump tube and smoke started to seep out around the wastegate/manifold flange. (The video below shows the smoke, it looks like its coming from the wastegate/dumptube flange, but it's not.) So I need to fix that leak.


[youtube]http://www.youtube.com/watch?v=avxmDY8Zq1U[/youtube]

My question is:

Should smoke be coming out of the dump tube with the car off, or should it be closed and not venting?

If it's supposed to be closed, then the only way smoke would be able to get through the wastegate to the dump tube would be if the wastegate was stuck open, right?

[chillmieste]

not 100% sure on if the dump is closed with engine off. BUt i am 100% sure you should not feel any exhaust coming out of the dump when ur engine is running. Check ur wastegate sealing ring, some people (including myself) have put them on upside down and it creates a leak from not sealing properly. anyway if it is on properly and it still leaks i would spend some money on a good WG as they are very important to a turbo setup, that is unless u r already using some baller stuff.

[C-Kwik]

The boost symptoms do kind of indicate its a problem on the exhaust side. Boost leaks large enough to cause that much loss in pressure would likely cause you to stall when you let off. Make sure your wastegate is on there tight and that the gasket between the manifold and wastegate isn't compromised. If the nuts/studs/bolts start to loosen, the gasket generally gets blown out as well (except for metal gaskets). And due to the heat cycles, its not uncommon for the hardware to come loose. If you haven't done so already, use some kind of a locking mechanism for the hardware. I had ended up using socket head bolts that were modified to accept safety wire. I went through a ton of gaskets before I did this.