Strange noise from turbo

[hitzkrieg]

I have a 94 touring wagon that was purchased recently, and now I'm noticing a strange noise from the turbo area, only when the engine is fully warmed up. It sounds like a rattling/grinding noise that flutters a bit under part throttle around 2500-3000rpm. When the car isn't at operating temperature, the turbo spools fine and sounds great. Even when it's making the noise, it doesn't seem to hesitate or misfire, and there's no oil consumption. The car has 93400 miles on it, and a stack of dealership maintenance receipts in the glove box. The oil was clean when I bought the car, but I recently changed it using 10w30 castrol syntec, a BG MOA and a Subaru oil filter. Not quite sure what's the cause of the noise, I'm hoping that I don't have to replace the turbo since I just bought the car and it has low mileage

[BoostedSubie]

Check the wastegate acuator, the rod, and the gate itself. The c clip that holds the rod to the lever that opens the gate on mine came loose one time so the waste gate was futtering and sounded like jingling keys under my hood. I don't know if thats the sound your talking about but check that the rod is tight and that the gate is fully closed.

[wtdash]

There are also many heat shields on the exhaust manifold and around the turbo area that could be loose. Most of mine have come loose over the years and needed to be 'fixed'.

Td

[hitzkrieg]

I don't think it's a heat shield or the waste gate, because it only makes the noise when the engine is fully warmed up. I checked the waste gate actuator, the vacuum line for it, the waste gate rod and c-clip, everything is tight and the actuator operates fine. I'm beginning to think it's the bearings in the turbo since it only makes the noise when the oil/engine is at operating temperature

[hitzkrieg]

I'm still confused on this noise, I pulled the intake hose from the turbo inlet while the turbo was warm, and there's no shaft play. Revving the engine with no load on it will not reproduce the noise. Is it possible for the wastegate actuator to malfunction when it's heat soaked?

[hitzkrieg]

So I'm bumping this old thread... replaced the turbo on my car today with a known good unit and I'm still having the issue with the whining/grinding noise when the turbo is supposed to be boosting. I replaced the vacuum hoses for everything mounted to the strut tower while I had the car apart. I know that the lines are all routed correctly. There are no cracks in any of the inlet hoses, the turbo to manifold hose or the bypass valve. The wastegate actuator functions normally and the rod is tight with no play. I'm thinking I should just replace the BCS, but I have no clue. Some input would be appreciated, I'm tired of trying to figure out what's wrong with the damn thing...

[wtdash]

Can you make a video/recording of the noise and post on youtube or somewhere?

[hitzkrieg]

I'll try to take a recording of the noise sometime soon, but I need to locate my video camera.

When the turbo is supposed to be boosting, it seems like the boost level fluctuates because I notice a drop in power when it makes the noise, but on occasion it does boost fine and has good power... the noise sounds like someone letting air slowly out of a balloon and completely replaces the normal whistle of the turbo when boosting. The only time the noise occurs is above 2200 rpm with moderate throttle while driving, also.

[asotwavb]

When i was home 6 months ago, my friend had a newer 08 WRX and just installed his uppipe.He called me up because it was making a crazy sound very similar to what your describing.

The flange on his uppipe to turbo was slightly warped, and would begin to leak out air and made a crazy weird noise like ive never heard. We at first thought it was a faulty turbo or wastegate.

He installed a new thicker gasket and was good to go.



Maybe this is a similar issue?

-William

[hitzkrieg]

When i was home 6 months ago, my friend had a newer 08 WRX and just installed his uppipe.He called me up because it was making a crazy sound very similar to what your describing.

The flange on his uppipe to turbo was slightly warped, and would begin to leak out air and made a crazy weird noise like ive never heard. We at first thought it was a faulty turbo or wastegate.

He installed a new thicker gasket and was good to go.



Maybe this is a similar issue?

-William

Thanks for the tip. I replaced both exhaust gaskets for the turbo and didn't notice anything unusual about the old up pipe gasket. That'd explain the loss of boost if it was leaking from the up pipe flange. I'll have a look at it tomorrow.

[wtdash]

How about your BPV?

[Legacy777]

I'd look at your BPV like Todd suggested.

Other thing you can do is to bypass the BCS and just run a vacuum line from the compressor outlet to the wastegate actuator solenoid. This will eliminate the BCS and all the electronics stuff as a potential cause.

I'd start with bypassing the BCS first and then check the BPV. That should confirm with relative certainty what the problem is....assuming it's one of those two things.