turbo to manifold bolts loosening- anyone else?

[diceman]

My M400 developed what i can only describe as a high pitched buzzing (not a whistle) under full boost whilst on track at bedford a couple of weeks ago. This was combined with a marked drop in power. I took it to the dealer where they diagnosed loose turbo/manifold bolts on the rear turbo and tightened them up.

Car was fine when I got it back but after a couple of hundred miles it's started happening again. :confused:

Just wondering if anyone else has had this happen. I'm also thinking they should not come loose so easily. I don't want to be making frequent trips to get this sorted :(

Hope everyone had a good time at Britcar. Couldn't come because of work committments but hope to make it to the next Noble track day.

[matt_fp]

Constant heat cycling can cause fastners to losen under certain circumstances. However when this occurs the fastners should be replaced not just re-torqued, its also a good idea to replace any gaskets between the two faces when replacing the fastners.

In short it needs four new fastners rather than just the old ones tightening up.

Best Regards
Matt

[adrian w]

get some nice cool air flowing over the turbo or it will keep happening.

[chillidog]

adrian w said:

get some nice cool air flowing over the turbo or it will keep happening.

How?
--
Richard

[diceman]

Thanks Matt. I'll ask the dealer to change the studs and the gasket this time.. Cheers

Adrian. If only it was so easy! probably have to change the whole rear aerodynamics to get air over that turbo. What i was thinking of doing is changing the rear mesh around the number plate to a more free flowing design.

[BrianJ]

Turbo gasket failures an endemic problem in my experience.

[z3stu]

Yeah had the same problem tried a new way of keeping the nuts tight. On escort RS Turbos they have a washer with flaps on it that you tap on to the side of the nut to hold it tight! Crossed fingers it is working fine at the moment!

[GreenV8S]

Do you have enough space to fit longer sleeved studs/bolts? The extra length gives them more stretch so they are more tolerant of thermal expansion changes.

[silversix]

K Nuts are the answer. designed for high temp aircraft applications, they are ideal for turbo's. the last half thread is slightlt deformed, so it locks in place. Or "squeeze" standard (stainless) nuts in a vice slightly, so that they a slightly tight when you put them on (be careful thet you don't damage the thead though). haven't had to try this on the M400, but it worked a treat on the Escort Cossie, and some time ago on a string of R5 turbo's.

[Adrian W]

PEC fan out of a Renault 5 and a bit of ducting works perfectly. Phile brett's got a picture I think.

Adrian

[ThatPhilBrettGuy]

Adrian W said:

PEC fan out of a Renault 5 and a bit of ducting works perfectly. Phile brett's got a picture I think. Adrian

I have. I'll post it up when my hosting solution is working again (i.e. the server in the spare room that's currently being a pain).

[diceman]

That would be good phil. Is the fan for the front or the rear turbo and has it stopped the loosening? Anyone know which one runs hottest? I'd guess the front one.

[Adrian W]

Sorry Phil did'nt mean to call you Phile........can't spell again

[ThatPhilBrettGuy]

Not the best picture I've ever taken, but you get the idea.

[chillidog]

Thanks Phil and Adrian.

Phil -
Do you simply just blow air directly onto the Turbo?

And it makes that much difference - i.e. prolonged life and things stay properly fixed?

Do you have it powered on all the time or is it switchable, if so how?
--
Richard

[ThatPhilBrettGuy]

It's Adrians car not mine, but yes it does blow straight on the turbo and I believe it runs all the time.

[Mike SA27]

do you have more details pics please phil? I would like to see in detail how everything was done, thanks in advance!

[adrian w]

Just make a hole in the heat shield, find a fan and some ducting,make sure nothing that can mealt gets to close,draw the cool air from one of the side ducts. Mines on all the time. Dont get the impression Noble will keep paying for gasket replacements as it's quite a big and expensive job, especially if you track the car.

[chillidog]

Adrian - have you only cooled the forward tubo because that's the one that gets hottest and has given you problems? Do you bother with the rear turbo?

I was also wondering if you could suck air through the oil cooler in the side pod and direct the air onto the turbo, so killing two birds with one stone.
--
Richard

[adrian w]

just the forward one, as it gets to hot. also its no big deal to change the gasket on the back one