Turbo Beginning To Go On Rb20det?

[mjfawke]

My engine has decided to start making a new noise - if I go from off-throttle to full throttle at reasonably high RPM (3k+) in 1'st/second gear, I get a squeal like a slipping fan belt for about half a second (and yes, I have checked the belt, and no - it's not wheelspin). No noise if it builds boost slowly. I can also get the noise by getting the revs up to 4K then going full throttle for an instant - but it's so damned noisy under the bonnet I can't work out where it's coming from (but it's not the fan belt). I'm thinking turbo thrust bearing... any dissenting opinions?

[crofte]

Pull off the air box lid and filter, give the bitch a tweak of the throttle and listen to the turbo. You should be able to determine any unsatisfactory noise. Failing that remove the pipework and check shaft, carefully.

[limpus]

Its highly likely its the turbo manifold gasket...have a look...

[DjeMz]

is ur bov blocked off?

when my bov started leaking it made a VERY high pitch squeal... just take the bov off, clean around the seal thingy and put it back on

[Leadfoot]

My engine has decided to start making a new noise - if I go from off-throttle to full throttle at reasonably high RPM (3k+) in 1'st/second gear, I get a squeal like a slipping fan belt for about half a second (and yes, I have checked the belt, and no - it's not wheelspin). No noise if it builds boost slowly. I can also get the noise by getting the revs up to 4K then going full throttle for an instant - but it's so damned noisy under the bonnet I can't work out where it's coming from (but it's not the fan belt). I'm thinking turbo thrust bearing... any dissenting opinions?

Yep, sounds like turbo bearings.

Had same thing. At first the squeal only came in under boost.

By the time I got home it was constant.

The best way I could describe it would be the "woooooooo" sound made by a crowd at the fireworks.

Even with turbo removed there was no real discernable play in the shaft. All turbine blades were attached. Turbo looked fine.

Rotating the shaft by hand the bearings felt a bit rough however even that was difficult to tell.

In the end, turbo replaced, no more noise.

[Fry_33]

I would be checking all of the hose clamps on your piping first. If one one these isn't tight you may have a leak which could only be present on boost.

[DVS JEZ]

Its highly likely its the turbo manifold gasket...have a look...

X2 very common, the gasket between the manifold and turbo starts to leak and the boost pressure whistles out.

[mjfawke]

Thanks everyone, but as the noise only occurs for about half a second, I don't think it's a leaking gasket or pipework. I also run a pod with 3" induction piping, so no issues hearing noises - but with the bonnet open free revving, all I can hear is serious suction noises from the inlet. A sticking BOV might be the answer if it is slow when closing.... I'll have a look at that next.

[Roy]

X2 very common, the gasket between the manifold and turbo starts to leak and the boost pressure whistles out.

x3 , simplest answer is often the right answer. Not common for the bearings to give out

[Fry_33]

Thanks everyone, but as the noise only occurs for about half a second, I don't think it's a leaking gasket or pipework. I also run a pod with 3" induction piping, so no issues hearing noises - but with the bonnet open free revving, all I can hear is serious suction noises from the inlet. A sticking BOV might be the answer if it is slow when closing.... I'll have a look at that next.

You will not hear the noise with the car parked and the hood up. The car will not be producing boost as it will not be under load. As stated the simplest answer is the best place to look first, mainly because it is the cheapest thing to do. There only needs to be a tiny leak, you won't hear it off boost but when on boost the pressures are high enough to make the difference.

[mjfawke]

... and as I said before, I can hear the noise when free-revving, I just can't work out where it's coming from.

And it's not the BOV. As an extra bit of info (left window open, driving alongside retaining wall so I can hear better) , the noise occurs for about 2 seconds in 1'st gear, and about half a second in 2'nd gear.

I think at this point, I'm just going to wait for the noise to change before looking further. It doesn't seem to be getting any worse, and it only happens when I abuse the car anyway.