whistle while boosting?

EvilAsPie

New member
So, while i was driving home in the crap storm Wednesday the legacy starting making a different noise while on boost. I wasn't even accelerating that fast given the weather. I'm used to a turbo making a whining noise, but now i am hearing a higher pitched whistle sound. I was having some over boosting issues, so i removed the MBC thinking that might have been it, but it wasn't and i am not running on wastegate boost.

Unfortunately i can only get it make the noise while boosting under a load so i can't hear it while under the hood. So i can't be certain it is coming from the turbo or somewhere else in the intake system. I have checked all hoses and vac lines.

I have no performance issues, just this strange whistle.

Has anyone ever hear of something like this before? Is it something i should worry about? And where would i even start to try to find the source?

Thanks.

 
If its a loud whistle or screaming noise often times that can mean you have an leak in the exhaust before the turbo or possibly a very small boost leak??

Generally a loud whistling or screaming is a small exhaust leak at a gasket area. There is so much air going through that uppipe at high load usually that's why you will get that sound. Generally that is what I've heard about or seen is the cause of that type of noise.

 
that would stand to reason, since the up pipe was leaking before and when we put new gaskets in it, it still didn't fit very well. that up pipe might just be pooched pete.

 
and if UP is leaking, escaping gases tend to cook plastic stuff nearby, so look for blackened, burnt, or melted plastic bits and/or wiring.

check esp closely around UP flange...sounds like that's your problem area

 
Sounds like that def could be it. There is a leak where the header connects to the UP and where the UP meets the turbo. The turbo leak is better then it was, but is still there. Probably means to UP is warped or something, but either leak could be the source i guess.

Sure wish i could check the UP without having to drop the entire exhaust cause it's all one piece. :
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remember?

Thanks everyone.

 
a cracked turbo or sticking wastegate will whistle while you drive
Wastegate was the first thing that immediatley came to mind when I read the op's thread topic...

Hard knowing w/o hearing the actual whistle though, right?

Best of luck figuring it out aspie.

 
So i've checked and tightened everything i can easily with no luck.

But, when i drove the car yesterday it sounded like the whistle was even louder, and starting sooner (as pressure was approaching 0 psi). It also sounded like the exhaust leak at the UP/Turbo was louder.

When i drove it today the exhaust sounded loud still, but the whistle was gone. So i would assume with the new gasket that the leak was whistling, and now that it is louder the whistle is not happening anymore.

The trouble is to try to tighten where the leak is i have to drop the entire exhaust. So i am going to try to leave work early today and give it a shot.

Fun fun!

 
Oh i know exactly where the exhaust leak is. >
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I was just unaware that an exhaust leak could whistle like that.

The main problem is stopping the exhaust leak. I just had the turbo off and replaced the gaskets in hoping it would fix the issue. Back to the drawing board now.

 
its just like putting a piece of grass between your thumbs an blowing

i would try doubling up on the gasket and some muffler cement or high temp form-a-gasket when reassembling

trying to tighten the gasket will just make it worse the gasket is already warp and blown out by now

 
i would try doubling up on the gasket and some muffler cement or high temp form-a-gasket when reassembling
Great suggestion. I even had everything ready to do that. Till i looked under there again and found the leak is actually under the flange. So the up pipe is actually cracked.

So i need an up pipe. An STi one will fit right in, or a WRX one (un-catted). Anyone got anything? I think i will PM urabusturbo, i think he had one.

Thanks again for all the input.

 
well at least you know what the problem is now! that's better then it was this morning!!

p.s. there are a ton on ebay for cheep money

 
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