It's not a belt

[Rawze]

Every time I have heard that metal-to-metal screeching -- most of the time the truck driver swears it is the turbocharger going bad but rarely it ever is. Shop gets you for a new turbo when in most cases all it was is the mounting gasket instead.

The most common cause of that horrible screech sound is actually the mounting gasket for the turbo itself or a manifold gasket blown out and/or failing and screeching very badly. Sounds horrible like someone letting the air out of a metal baloon and is very loud. Some describe it as A metal to metal high pitched white-noise type of screech. Sometimes you also loose a bit of power when it screeches because it looses back-pressure to drive the turbo when it does it too.

There can also be a problem with the turbo, don't rule it out, but the screeching itself is not likely to be the turbine. When the turbine is touching something it does not make a screeching sound but a very distinct high pitch whine instead described the same as a ringing in your ear, and has no white-noise screeching mixed in.

Do a turbo inspection and look for damaged vanes and metal shavings. There is supposed to be about 0.045" of side-play in the turbine. It is not supposed to be completely rigid. If it is not the turbo then it is more likely to be the mounting gasket where the turbo meets the manifold.

Had guys come over here after 2 different shops said his turbo was toast. ... He got it screeching really badly while here and I walked over to the turbo and touched the side of the mounting gasket (on one of the tabs of the gasket sticking out) with a long screwdriver and the sound stopped immediately. -- New gasket later and it ran like a champ again. - Not saying this is your problem but that is where I would definitely look first if no metal shavings or visible damage to the turbo were found.


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Even if it is only the mounting gasket, it is bad for the turbo and the truck. It will cause fual mileage loss and a lot of other boost related issues including problems with the regen process and excess soot problems in the engine. It will also cause hot exhaust gasses to drill holes and/or etch the mounting surfaces where it is leaking and cause sealing issues with the new gasket. This in turn can make for repeated failures and expensive component replacement to get it stopped/sealed properly.

I.E> -- IT IS A BIG DEAL AND NEEDS TO BE FIXED!!! Unlike what some complete idiot of a mechanic would tell you.

Tags:

turbo screech, turbo squeal, turbo rub, metal baloon, metal to metal sound