hey

my car is a series 1 r33 gts25t. Lately my turbo has been making a very faint whining noise every every now and then. This happens between -30cmHg and -20cmHg (read out on blitz dual sbc spec s). This is the only time i hear this noise (under very light throttle), never when making positive boost or under hard/harder acceleration.

Is my turbo on the way out? Or is a maybe a slight leak somewhere, or possibly something else?

I've searched some other posts and people say they get a squeal/whine noise when making boost at say 3500rpm, yet i get a faint whine at about 1800rpm, so i'm not too sure...

Is it blowing any smoke on boost that you've noticed? Or is it just the faint whining?

How many kms on the car? What sort of boost are/have you been running?

no, it doesn't blow any smoke (looked for that, and have also looked for any oil coming out of the turbo or piping and there is none).

the car has done about 104000km (assuming if it has been wound back, then more than this figure). It is a 93 model.

boost is stock and a setting at 10-11psi. But before the ebc (about 1 and 1/2 yrs ago) who knows what it could have spiked to during the period after the exhaust was fitted, as all i had to go by was the stock boost gauge.

mine does the same on slight acceleration - changed oil regularly and all seems fine tho - still makes slight whine (like a dog whistle almost) which I've heard on lots of others - bear in mind this turbo is spooling up to the phenomenal speeds it spins at just before the actuator opens so on slight accel your gonna hear something spin up - I haven't heard a totally silent one yet myself but I'm no expert either so every skyline I've driven or drove in might have been knackered lol!

Could quite possibly be a small leak in your induction system somewhere. Check hose clamps, holes in piping, maybe some silicone hose got scraped on the ground coming out of your cooler. You get the drift.

it could also be the turbo gasket starting to leak, i would check to make sure all bolts on the turbo are tight, once the turbo starts sound like a super charger then you have issues

the slight noise you could be hearing could be air passing through the bov. there is a point where you can hold the throttle where the bov will be open slightly. and since there is air permanently leaking around the bov through a recirculation hole, it can cause a whistle.

Yeah I'd think it's not really anything to worry about.. turbos on their way out usually do something more drastic than make a slight whistle at lowish throttle....

hey mad082 - you mention a bov (I'm assuming thats a blow off valve heh!) - do all r33gtst's have them or are they aftermarket addition?

I only ask as mine too makes this subtle whistle and it is at a certain point on the throttle as you said but I dont have an aftermarket dump valve on my car

theres other signs that your turbo is going anyhow - small puddles of oil in that metal piping that feeds up from your intercooler. There can be slight smears in the pipe that you can wipe of with your finger (charge pipe is it?) so dont fret if you pull it off and see that but if you pull if off and see it dripping then I'd be a bit more worried

smoke out the back on hard boost - basically oil escaping I think.

only know this as I had to disconnect mine getting to the spark plugs and we checked this area recently

all 33's came stock with a blow off valve... although the correct name is compressor bypass valve. it is situated just before the throttle body, on the cabin side of the piping. the are hooked back up to the intake between the air filter and the turbo, so that when you lift off the throttle the air goes back through the turbo to keep it spinning (like blowing on a kids windmill that you get from fair).

fantastic thanks mad

also i had oil dripping out of my intercooler piping at the throttle body, and a small amount through the piping before i did my frount mount. I thought it might've been the turbo on the way out, but after a few weeks with the front mount i pulled one of the new pipes off and there was no trace of oil at all. it turns out that the stock front seal on the turbo will always leak a tiny amount of oil. the front seal is like a piston ring. it isn't a full circle. it has a slight gap in it.

so my problem was just old oil, and a bit of blow by.

Edited June 21, 200620 yr by mad082

thanks guys. I will get the car on a hoist and a have a good look to check for tiny leaks in intercooler piping, as well as make sure the bolts on the tubo aren't loose.

Didn't think of the that tiny air recircualtion hole in stock bov, could be that.

Cheers...

Don't discount the bearings.

Mine had that whine on boost, it was on and off, and didn't really effect the performance.

I did a track day at Winton, all was good, but on the video, I coul hear it whining. high pitched noise.

A week later the bearings shat themselves.

So I got a high flow.

mine makes noises when my oil temp gets up

new turbo on the way before it breaks