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GTSBoy

What happens when your turbo nuts fall off

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Had a little fun on the weekend, thought it might be a learning moment for some others.

Recently there have been odd squeally noises when my car was on boost. Not all the time, usually while not fully hot under the bonnet. Intermittent nature of it made me wonder if it could be a gasket leak on the hot side (sounded like it was on the LHS of vehicle).

Sort of gradually became a little more frequent. So I chucked the inspection camera in under the turbo heat shield and found, to my mild horror, that the rear lower turbo nut had dropped off at some point. The lock tab for it was still bent up sufficiently that you'd think it impossible for it to happen. But happen it did.

What was somewhat more frightening was that peaking the camera on the other side showed that BOTH the other two nuts on the front side were loose. Several threads out. Both still in contact with their locking tabs. WTF! Only the top rear nut was tight.

So there you have it. Turbo was barely held on to the manifold and I could barely tell the difference in the car's performance. Sure, it was no doubt a creeping death onset and I didn't notice the slow decline in its spooling response, but it was still pretty much as fast as it ever was. After doing up the one nut that I could actually get a tool onto (so obviously, I have some more work to do!) it doesn't shriek any more and it seems to come on boost a little more aggressively. But there you go. It is surprising how little effect having the turbo almost to the point of falling off can have.

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I guess the rate of leakage from the flange was still less than what would have been wastegated, so the wastegate would have stayed closed for longer to compensate?

Or perhaps you just drive so slow already that the impact was negligible? :P 

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See post from September last year in the EFR thread about my encounter with this issue...

 

It is worth noting that I did do a PB at QR with the issue also. turbo was to the point where you could move it a few mm at that point. drove home too with no issues

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42 minutes ago, GTofuS-T said:

I guess the rate of leakage from the flange was still less than what would have been wastegated, so the wastegate would have stayed closed for longer to compensate?

Yes, absolutely. At least when it is actively controlling boost. I think if the gap is wide enough to leak noticeably during spool, that it will kill spool (compared to having the WG held closed by the controller, like it is supposed to be). And after tightening it back up and having it feel a little better coming on boost, it was probably leaking enough.

42 minutes ago, GTofuS-T said:

Or perhaps you just drive so slow already that the impact was negligible?

Most of the time yes. I don't have anywhere near as much power as many on here have, but even that is enough to cost a great deal in tyres and -ve attention from the guys who drive the unmarked cop cars.

Edited by GTSBoy
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I've found those OEM locking tabs to be useless, even when hammered with an extension so it forms around the nut....so i don't bother with them anymore.

Only thing that has stayed in place for me was using inconel studs and copper locktab nuts....stayed on damn tight, so far.

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Yes, well, I don't know about the studs (in my application they would reasonably be considered overkill) but I may try some copper nuts.

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