cpt_koolbeenz

Somewhere I was reading that the turbos on 951's are not supposed to make noise if everything is working properly... (should I believe it?)
I hear mine whining kinda like a VERY faint police sirin when it is spooling down after RPM drops from 4.5k down to about 2k...

Is this normal or would the noise indicate a leak after the turbo causing the turbo to spin really fast, making the noise?
Everything elese seems normal - boost, acceleration, etc. (maybe some very light surging upon acceleration sometimes - not sure if that is because it wasn't warmed up yet or what...)


Thanks
Chris
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UPDATE:

users.adelphia.net/~robertlange/1.mp3


Can anyone host this for me?
It only works sometimes

Okay guys here is the noise...

It is the end of the clip that you hear it...
It was recorded in the cab...
I also recorded it in the engine, however it is not as loud for some reason?

Is this sound normal? It is a little more pronounced in real life.

Thanks
Chris

cpt_koolbeenz

ne1 with 951 that can answer??

coolhand

You hear a whine when your RPM's drop? Is that in gear? I've never heard that before.

cpt_koolbeenz

hm... no i think it is with the clutch in when im shifting - - maybe in gear - - i will find out tomorrow and maybe i can catch the sound on tape and post an mp3...

it smells a little rich when under boost... possibly indicating a leak in the pressure side of the turbo??

any other suggestions?

cpt_koolbeenz

951 Owners HELP!
I will try to do the above today...

Perry 951

Yes.. you should check all your hoses and connections. If the intake is stock, you should not hear it spool unless you are really trying to hear it. If it is running rich under boost, and did not before you heard the sound, chances are you have a leak.

Even with my MAF and big turbo, the compressor whine is not too noticeable. Now.. you can hear the hot side spin up and down through the exhaust, but that is supposed to be there.

schlag

Sure the sound isn't coming from the gearbox or transmission?
Mine does that because its old and beat.

cpt_koolbeenz

"Now.. you can hear the hot side spin up and down through the exhaust, but that is supposed to be there."

Hmm... now I have to find out where I hear it... It seems like it is comming from the drivers side engine compartment (turbo location right?)...

The noise seems to be when im not pulling a load...
I'll be right back (need to go check it)...

cpt_koolbeenz

users.adelphia.net/~robertlange/1.mp3

Okay guys here is the noise...

It is the end of the clip that you hear it...
It was recorded in the cab...
I also recorded it in the engine, however it is not as loud for some reason?

Is this sound normal? It is a little more pronounced in real life.

Thanks
Chris

Redeye

Just a shot in the dark but, is your bypass valve hooked up correctly?

Perry 951

That is not turbo whine. It sounds like an accessory. Free rev the motor and see if the noise is there. If it is, it ain't the turbo.

Velvet951

I have the EXACT SAME THING GOING ON. It only happens when I'm under boost. Nothing at idle or just reving while stationary. It's really pissing me off. I ripped everyhing out on the inlet side. I think it's exhaust related. I also just replaced my BOV, so I don't think it's that. Please HELP US. I can tell it's killing my boost. My car doesn't have any punch, just smooth roll on. The turbo is still present. Could it be the wastegate? It's only loud in the cabin.

James86-951

I can't load the mp3, but my old 300 turbo had a very noticable whine from the engine compartment.(Most noticable under light acceleration up to 1 bar. (0 psi)) It was even louder after some upgrades. The turbo was a fresh rebuild from a reputable shop.

Do you have stock intercooler pipes, etc?

Velvet951

James, That's exactly it! Noise under light acceleration! What was it???? Yes I have stock IC pipes. Checked 'em all. Tight and new.

James86-951

I never found out why it made that noise. It had good oil seals and held boost well. The wastegate for the turbo was actualy on the hot side itself and the rod had been replaced with a threaded rod for me to adj max pressure. (up, of course) It ran 30 psi all the time and never gave me problems. (Great headgaskets and machine work.)

It became more noticable after I wrapped the crossover pipes and down pipes with 1/8" thermal wrap. The turbo itself was never wrapped because of oil coking concerns. (I hadn't purchased a turbo timer yet.)

The shop that rebuilt it didn't really have an explanation. They tested it and said it was in good shape.

If it doesn't have any axial play, the clearances are good and the bushings are good, just run with it. Oh and go with synthetic oil. It won't coke nearly as easy as petroleum oil.