take your dump pipe off and have a feel around inside might be something loose... if u cant find anything then just disconnect the wastegate, the more boost the better

99% sure it's not the manifold gasket.... I recently ran it with the wastegate linkage disconnected - The buzzing sound disappeared.

Pretty sure it's not the diaphram in the wastegate actuator, but I'll check that too.

Hmmm...... Food for thought.
I'm now thinking it's either the wastegate shaft / housing bushings or a problem at the actual wastegate seats.
Looks like I'm resigned to pulling the turbo off, cracking it open & taking a peek.

Quote:

Reading your suggestion, I can see where your handle comes from...

Coops, I have an external waste gate, sometimes it would also start barking and buzzing, the car would then jerk and choke when that happened, although that was right near the end. Eventually I found out that the gate's valve had come loose from the actuator and it's membrane. Tightening up the little grub screws fixed the problem. Just a thought that the little flap/valve might be worked loose from it's shaft, that's if the other suggestions don't serve up anything...

are u sure it's not the turbo/manifold gasket?

Good idea Mike.... I'll try to hook up a spring somehow.

I'd ask you how your project is going, but I don't want to tie you down for the next hour thinking about which project I'm talking about .

Knock it back a gear, problem solved. . .

Can you wire another spring alongside temporarily to take up the slop? A bit of chewy even to pinpoint the cause?

I don't imagine the wastegate would be starting to lift off the seat during cruise.

I'm getting a buzzing sound coming out of the turbo @ 2000 rpm.

I'm 90% sure the buzzing is happening at the wastegate at the point where the exhaust gas pressure @ the wastegate is starting to equalize against the force being supplied by the actuator.

The shaft bushings where the linkage extends through the turbo housing seem a bit sloppy & probably need to be replaced..... Not sure if this is the source of the buzzing or if it's the actual wastegate vibrating on its seat.

Don't really want to go to the trouble of removing the turbo if I can help it.

What I was wondering was if there's any way you can adjust the linkage length & if this will change the rpm where the buzzing occurs.
2000rpm is town cruizing speed...... AND THE BUZZING IS DRIVING ME CRAZY!

Running a T28 turbo off a S15 200sx.