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Turbo flutter?! NA-t


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Guys during one of my start ups I noticed a strange sound coming off what I think is the turbo when I back off the revs. Have a listen to the above video it happens straight after I drop the throttle off.

The car hasn't been mapped yet nor set up properly with regards to the boost controller.

You will also notice that the turbo isn't spinning at idle but from what I have read this can happen on new turbos

 

Any advice would be appreciated I don't really want to start breaking the turbo down now that I have just finished

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Sounds to me like the fins are catching on the housing as it slows down. Is there any shaft play at all?

 

I agree with Listy, it would also explain why the compressor wheel doesn't spin until you give it some revs.

 

Edit - just re-read you first post where you've mentioned sometimes the compressor wheel does not spin at idle on new turbos. I'm unsure but it certainly sounds like something is catching.

Edited by Rich.2211 (see edit history)
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thanks guys, im going to take the downpipe off later and have a look inside hopefulyl its nothing i have done when fitting. There is no shaft play at all on the turbo, from the inlet side i have rotated it by hand and i cant see or hear it catching so going to check the turbine.

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Yea watched the turbo from startup, i did have it spinning for quite some time the other day but yesterday it stopped after about 30s of the engine warming up and takes about 1300-1400 rpm to get it turbing. Whne it does turn you can back off to idle and it will spin for a little while doesnt seem to wander about though or do anything strange. I will break the turbo down and check everything

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Right just to keep you guys in the picture . I took the turbo apart tonight to discover why it wasn't spinning at idle an making the flutter.

I found that the turbine (exhaust housing) had some markings which look an identical shape to the blades. There is no shaft play or bent blades in the turbine or even shaft wobble. I also found that I hadn't tightened one of the retaining bolts connecting the internal parts to the exhaust housing so I thought it might have been that. Spun the turbo a few times no sound and rotated fine.nput all back together. Same issue, the turbo spins and then eventually stops however I found once th oil was hot the turbo kept spinning which is a result I suppose. However the blade catching noise is still there when the turbo slows down. I can only put this down to poor tolerances in the turbos manufacturer I suppose I will just have to deal with it until the blades /housing rub enough off each other to stop it.

I may still pull the turbo again and attempt to rectify this but I have no idea how.

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It's not on the intake side it's the exhaust so there only going one way and that's out th exhaust. I'm going to take it apart again and have a play it wouldnt be the bolts holding the mechanical parts into the housing would it?

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My first thought is taking material off the turbine will solve the problem. Which I think it will.

 

My second thought, is how much weight distribution is there on those blades. The weight being equal will put the bearing in a state of stress. Having an uneven weight distribution may cause a higher stress bending the shaft. I'm not sure how tight the tolerances are on the bearings, or even how close to the materials tensile limits the turbo's are.

 

I may be over thinking this. But having an un equal weight on a blade that's spinning at 15,000rpm + may cause other problems. Do some research before you considering using un even blades. 'Just' in case.

 

Dnk or Chris Wilson is probably a good person to speak to about this.

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just a quick note which happened to me today on the downpipe if you have prewelding screw holes for lambda sensors if you aint using any of them make sure the bolt on that is tight. As i had the exact same noise and problem today it sounded like its coming from the turbo but in the end it was the bolts on the downpipe loose.

Only difference is my turbo spins on idle :eyebrows:

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Right guys, still stuck. I ran her up again today after resisting the internals and making sure everything was tight, spins easily. Rev up engine slightly and we get the flutter again. So for some reason I decided to hold the turbo stopped and rev up slightly. Again the flutter happened. So it's not the blades catching? What the hell is it. I am now starting to suspect my oil drain/ pressure / oil type causing the issue

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Okay I just managed to watch the vid, sounds like something is blowing to me, is you waste gate not stuck open?

This would be why the turbo I not spining,

Even if the turbo is not on the manifold correctly ,

 

Was there even any signs of the turbo hitting in the housing?

Also I dont know how easy it would be to hold a correctly working turbo I know I wouldnt put my finger near mine

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Right just to keep you guys in the picture . I took the turbo apart tonight to discover why it wasn't spinning at idle an making the flutter.

I found that the turbine (exhaust housing) had some markings which look an identical shape to the blades.

 

this is what started the talk about blades hitting :)

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Yea that was my initial thought but The marks were just in the carbon rather than cutting into the turbine, having thought about it if the turbo wasn't spinning the blades would leave marks as the exhaust carbon would sit around the blades rather than be passed out.

How would I check if the wastegate is stuck open and why would it be? Even at 2k rpm I can hold the turbo blades still. I will rip it all out again tomorrow and check the wastegate bolts etc.

I am starting to loose my rag with this tbh there might be a for sale thread soon, or even worse a BBQ probably not the best time especially after this week at work bearing bad news

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I would not have a clue why your wastegate would be open but I just seems as if it is best way to check would be rev your engine and feel the screemer pipe if you have exhaust gas coming out of it you have found your problem,

Also is you manifold good leaking there would stop the turbo spinning

 

If you can spin the turbo in situe with out the engine on easy then it should spin with the exhaust gas, IF preasure is being kept

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I would not have a clue why your wastegate would be open but I just seems as if it is best way to check would be rev your engine and feel the screemer pipe if you have exhaust gas coming out of it you have found your problem,

Also is you manifold good leaking there would stop the turbo spinning

 

If you can spin the turbo in situe with out the engine on easy then it should spin with the exhaust gas, IF preasure is being kept

 

Great advice right there^

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