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Turbo Beginning To Go On Rb20det?

mjfawke

By mjfawke,
in Engines & Forced Induction

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mjfawke Collaborator

mjfawke

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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?

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crofte Collaborator

crofte

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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.

Leadfoot Enthusiast

Leadfoot

Posted
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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.

mjfawke Collaborator

mjfawke

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  • Author
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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.

Fry_33 Proficient

Fry_33

Posted
Posted
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 Collaborator

mjfawke

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  • Author
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... 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.

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