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Help Needed! High Pitched Whining Noise When Boosting...

pixel8r

By pixel8r,
in Four Door Family & Wagoneers

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Spammeoff Contributor

Spammeoff

Posted
Posted

So tonight I blocked the little 2-3mm hole in the bov with some duct tape and went out and tried to stall the engine (thinking it would.. see above), but nope no stalling at all. So that little hole will serve some purpose, but blocking it didn't cause stalling. So I put my bov blanking plate back on for another test to be sure, and yep, stalling again. Btw all testing has been done once engine at operating temp, won't stall when it's cold.

So I figure the best solution for me is to refit the factory bov with that little hole permanently blocked (as its a boost leak in my opinion). I figure it'd be best to weld that hole, anything you jam in there you risk going through the motor.

So then no stalling, but I will test that bov for leakage even with that bypass hole blocked, last time I tested it I didn't know about that hole, so naturally I thought bov was leaking! I wonder if many others have made that mistake.

But of course Nissan put that little air bypass through the bov back to the turbo inlet for some reason, I wonder what I'd be loosing by blocking it off...

pixel8r Mentor

pixel8r

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I originally only blocked off my bov completely just to diagnose whether the bov was leaking or not. ie. by isolating different parts its easier to locate where a problem is.

After taking it for a run down the road and discovering the noise was still there, I took it back and put everything back together with the bov in place as it should be.

I agree with the other posts - the bov is there for a reason, and blocking it off will cause air to rush back through the turbo which can only be a bad thing.

Spammeoff Contributor

Spammeoff

Posted
Posted

Fair enough, if the valve body isn't leaking under whatever boost your running, and the car's an auto, then it certainly isn't doing any harm. The small hole is still some sort of compromise though, a calculated boost leak to provide some other functionality that I'm not aware of.

BensDR30 Experienced

BensDR30

Posted
Posted
Hi all,

I have a '99 Stagea S2 (neo) and since I bought it back around march/april its been doing this squeal / whining noise under the bonnet when the turbo spools up. Its fairly loud too.

It seems the faster the turbo spins, the higher pitched the noise gets.

I've recently done the mod to the stock boost solenoid where you ground one of the wires so it now runs 7-8 psi boost and the higher boost means the noise now reaches a higher "note" when it maxes out.

Haven't had the turbo properly checked out but on just taking it for a test drive some people have said its probably the turbo on its way out and others have said its a leak in the factory blow off valve.

the car is completely stock and has made this noise since i bought it.

Any help as to what it is?

A ticking noise is usually a leak at the manifold/head. A squealing is indicative of a leak at the base of the turbine to the manifold. I blew out a turbine base gasket in my Z a few years back and it squealed - LOUD!

Ska Grand Master

Ska

Posted
Posted

This "little hole" you are talking about, it is on the inside of the bov right? Buy a Bic brand ball point pen, on the opposite end of the pen insert it's like a little plug to fill the other end of the pen. Anyway take that out and whack it into the hole on the bottom of the bov, I did that to my r33 bov and it stayed there for 2.5yrs with no problems, didnt notice any difference though and in the end cbf taking it all off to get it out, so it stayed in :thumbsup:

Spammeoff Contributor

Spammeoff

Posted
Posted

Haha, how'd you figure that out....?? Not a bad trick, just before now I dropped bov off at engineering shop to have hole welded up, and yes small one on underside of bov. Setting up the iebc this weekend, so wanted to make the most of it I guess.

Be interesting to pressure test my intake for leaks now..

Ska Grand Master

Ska

Posted
Posted

I didnt figure it out, as I said this exact subject has been thrashed out on SAu more times then a thai hooker gets laid! Do a search and you will find heaps of info!

Ska Grand Master

Ska

Posted
Posted

Well i am bored so went searching and found a couple of threads about the flutter sound and bov's

http://www.skylinesaustralia.com/forums/in...=126045&hl=

http://www.skylinesaustralia.com/forums/in...c=60654&hl=

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