weird noise past 4500 rpm's

[mkiii 4 life]

My car is making a weird screetching type of high pitch noise past 4500 rpms. Im not sure what it is. I just got a new mbc and now im at 9 psi and it is making this noise only while boosting. Any ideas? My mods are: intake, full 3" exhaust, joe p mbc at 9 psi, and bosch bpv. Any ideas would be helpful.

 

[radiod]

Checked for any boost leaks? It could be an intake air escaping causing a whistling noise.

 

[Quin]

Check the turbo for shaft play. Could be the compressor wheel grinding against the housing.

 

[mkiii 4 life]

i have not checked for boost leaks. The turbo had some side to side shaft play last time i checked. I will check again soon. Car also blows some black smoke at WOT

 

[ben1984j]

My last car (MR2 turbo) did this exact same thing - a weird screeching sound that only happened on boost. Turned out to be a leak in the exhaust manifold. So +1 on checking for boost leaks. They can cause black smoke too, or so I've read on here.

 

[mkiii 4 life]

thenks for the help guys. This weekend i will spend some time searching for the problem. The only obvious place i could think of a leak is the on the accordion hose where it connects to the turbo the clamp is bad and i can't tighten it all the way. The first thing i will do is replace that when i check the shaft play.

 

[mkiii 4 life]

Now it is starting to make the noise at 3500 rpm's. Im just too damn busy to look at it. Hopefully i will have time this weekend.

 

[mkiii 4 life]

I looked over the car today and i think their is a little more shaft play than their was last time i checked. Should their be any shaft play? I also checked the exhaust manifold, ic pipes, and made sure the downpipe was tight on the turbo. Their were a few loose nuts on the exhaust manifold but now they are all tight and it is still making the same noise :nono:. So im guessing its my turbo?

 

[mkiii 4 life]

I just found this video on youtube and my turbo sounds just like this one.
http://www.youtube.com/watch?v=W5rUiBQFCs0&feature=related

 

[bozosoku]

I had a similar whistling sound during transition from vacuum to boost, turned out to be a loose spring in the BOV caused the valve to flutter at certain speed. A new BOV solved the problem.

 

[mkiii 4 life]

Maybe i should put the stock bpv back on and try that

 

[ft413]

did you recirculate your new blow off valve? im assuming that you have new one because you said you took the stock one off.

 

[mkiii 4 life]

yes i recirculated the bpv. its a bosch bpv. I just put the stock one back on and that wasnt the problem. Any other ideas?

 

[mk3tattoos]

i had the same problem, it turned out to be a bad manifold to turbo gasket, once the bolts back out the damage is done. You can not just tighten it up, you need to replace it.

it might be a good idea to get new studs in there as well.

 

[mkiii 4 life]

i had the same problem, it turned out to be a bad manifold to turbo gasket, once the bolts back out the damage is done. You can not just tighten it up, you need to replace it.

it might be a good idea to get new studs in there as well.

thanks for the help. The bolts werent too loose. I turned the wrench less than 1 full 360 degree turn on each bolt. You think the gasket would be bad?

 

[mkiii 4 life]

Their is no way to tell if the gasket is bad without taking the turbo off right? I guess i might have to take the turbo off :dunno:

 

[mkiii 4 life]

Would the car be running bad if it was the turbo? I noticed these holes in the manifold the other day when i was looking over the car. Could this be the problem?

 

[supra90turbo]

Checked all the bolts on the manifold and turbo? My supra made that noise, had some loose bolts, so I tightened them but it was too late, blew the gasket out between the turbo and manifold.

I bet that's what it is.

 

[mkiii 4 life]

Checked all the bolts on the manifold and turbo? My supra made that noise, had some loose bolts, so I tightened them but it was too late, blew the gasket out between the turbo and manifold.

I bet that's what it is.

I am starting to think its the gaskets. The nuts on the manifold where it connects to the head have come loose multiple times