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Turbo noise

HighSierra86

HighSierra86

Active Member
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Location
Northwest CT
So after about 6 months, I've decided to clean up my suburban and drive it. I planned on just fixing it then turn around and sell it quick, but I think I am just gonna drive it for now. Been back and forth to the junkyard and have the interior all cleaned up nice now, and I've been cleaning up the exterior as well.

Anyways, put plates on it today and went for a test drive as I haven't driven it much more than around the farm for the last few months. The truck now has a whine that seems to be in sync with when the turbo spools. It's not the turbo whistle, and it dosent seem to be a drivetrain whine.

Turbo is I belive a gm4, the tag is unreadable. But it has a fair amount of shaft play. Not really end play but side to side. Spins freely and the wg seems to be functioning properly.

So I guess what I am trying to find out here is if it is possible that a bad bearing could create this noise or if it could be something else. It sounded fine when I purchased the burb back in the fall, but having sit all winter I'm wondering if it picked up some moisture/rust on a bearing. Thanks ahead for the replies, and by just FYI the truck has 208k
 
buddy said:
Did you change the intake on it, or does it still have the stock rectangle?
Click to expand...

Has the stock rectangle as of now, but i also tried tried an elbow and k&n filter with no difference in noise. I could hear the whistle a bit more as expected with the k&n but that was it
 
Check your heat shield between the turbo and and injectors. My 92 had an annoying high frequency vibration/whine around 1800rpms.

Since then, I always put some RTV in the slots on the bottom of the heatshield to minimize the chance of it happening again.
 
midniteplowboyy said:
Check your heat shield between the turbo and and injectors. My 92 had an annoying high frequency vibration/whine around 1800rpms.

Since then, I always put some RTV in the slots on the bottom of the heatshield to minimize the chance of it happening again.
Click to expand...

Ill check the shields. The noise is only under load. If you increase the rpms in park, you will never hear the noise. Seems to only be while driving and over 1600 rpms. Im trying to remember, but i think it drops off at high rpms as well, just about exactaly where the factory vaccum setup would drop boost pressures. I might try to run a temporary boost guage to see if this is the case.

As for the exhaust it is stock. I havent done anything else other than glow plugs, lift pump, fuel filter, ops, and the cps since I bought it.
 
Checked the heat shields yesterday....front side was loose but had no effect on the whine. The whine can be heard very slightly in park when you drop rpms from say about 2800 or so. I think im just gonna swap in the gm4 from my other truck to see if that gets rid of it or not.

And on a side note.....pmd crapped out while i was running the truck to listen for the noise. Ah well, just one more thing to buy now. Anyone have a cooler and pmd for sale?? haha i need kenny's suicide smiley.

But I did repaint all my rims this weekend, along with the fender flares, inner fender wells, and the frame. Looks much better now
 
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