Loose Turbo Bolts - growing problem

[Jmac]

Eddy you animal If you are in a hurry boss , try studs and nuts, even a tack with stick weld tack , if you need to loosen for any reason then a tack will break off with force , ive thought of this many times. Studs and nuts are a common fix on the big dinner plate turbos, even to a point rethreading the turbo. Im just taking a wee bit longer with mines as i would like to see a simpler fix.
Cheers
Jmac

[gregozedobe]

Apart from access difficulties, why wouldn't locking tabs work for this problem ?

If you bend them up hard against the face of the nut/bolt it can't move like it can with lock wires. Admittedly my experience was with driven sprockets on motorcycle rear wheels, but in that application they seemed to provide a simple but secure mechanical lock (as long as they were of heavy enough metal and bent up properly so there couldn't be any movement).

[Eddy]

Apart from access difficulties, why wouldn't locking tabs work for this problem ?

If you bend them up hard against the face of the nut/bolt it can't move like it can with lock wires. Admittedly my experience was with driven sprockets on motorcycle rear wheels.

Hoyhoy.

The heat is the major difference.

[Eddy]

MACCAA fabricated an additional support from the engine block to the turbo housing, but I can't say whether this was a solution.

Hoyhoy.

Well this might be the answer but me is going from the engine block to the exhaust between the flange & the flexy joint. A long time turbo mob here in Brisy reckon that the weight of the exhaust is the problem. Being manufactured as we speak in a solid way.
Now need some...

[Jmac]

Hoyhoy.

Well this might be the answer but me is going from the engine block to the exhaust between the flange & the flexy joint. A long time turbo mob here in Brisy reckon that the weight of the exhaust is the problem. Being manufactured as we speak in a solid way.
Now need some...

Yeah, weight, heat, vibration, pulse and pressure, lots of stuff going on down there
Jmac

[gregozedobe]

The heat is the major difference.

Yeah, weight, heat, vibration, pulse and pressure, lots of stuff going on down there
Jmac

I can see that, but has anyone actually tried locking tabs with a heavy enough metal that doesn't soften when heated ? I'm trying to understand what is really going on - this doesn't seem like it should be such a difficult mechanical problem, but it obviously is for some engines.

As long as the locking tabs are mechanically strong enough to prevent the nut or head of the bolt from rotating then they simply can't loosen by movement - only by stretching of the bolt/stud (which is a completely different mechanical issue to undoing).

If it is the latter case then the bolts/studs aren't strong enough for the job they are being asked to do. The obvious solution then is to get stronger bolts/studs made of different material and/or thicker (I'm assuming it would be difficult/impractical to add more studs/bolts).

[DarkCloudNebulae]

Hi Guys and Gals,
I have read this thread through, and was wondering if I could get some more info for myself and potentially others about what cars are affected? Guy H has mentioned that hard driven (stock) cars seem to suffer more, however I have noticed that some members with hard driven cars are saying they still have not seen/suffered the problem. Is it possible to ask those that have had the problem list the build date of their car, and possibly the mods that they had when this first occurred?

It sounds as though its not a problem of the bolts undoing, but of them being stretched, has anyone investigated the previously mentioned idea of brass bolts? Or found a bolt hard enough that doesn't stretch?
Could a "exhaust flexer" (sorry probably the wrong name for the part) be fitted from cars that don't suffer this problem to the polo exhaust?

Cheers!
DCN

[Jmac]

How hard do you want the bolts mate, they are 12.9 already, my lock idea is using mild steel to allow for expanding and contracting as for those in the know the metals like Stainless and likes turn to crap at extreme heat. The idea is very good but in practice has some hiccups, once ironed out should be good.
Cheers
Jmac

[DarkCloudNebulae]

Sorry Jmac, I don't have much experience with these bolts in particular or engineering at all really. (Biological Scientist) I'm always interested in learning a little more about the problems and ways to fix them though...

So if the bolts are as hard as they can go, then really the place that the force is coming from needs to be identified to help a solution? If its the exhaust twisting on the bolts, then a better exhaust flexer or harder mounts for the exhaust could help? Or if its just that the bolts are stretching in use by expansion of the turbo and exhaust at the gasket, can a more flexible/compressible/compliant gasket be used? One that allows more expansion/contraction ability so that the bolts are under less stretch?

Cheers

[Jmac]

Hey mate dont be sorry , your input that i can see is very valid, good to see in my opinion, and your train of thought is good, im with you there. Ive now had a Golf 4 with loose bolts today The turb pretty much hangs off the manifold the same way, this Golf is untouched, pretty much virginal in every way, but was loosing boost so i went through it, fixed some vac lines and thought i would check the turbo bolts and loose as a goose. Had a few chipped Polos loose too so no real trend to be honest. My idea is very much to stop any turn the bolt be it 16mm head or 17mm. I was going to go studs and brass nuts if this fails. Ive lock wired a K04 that came loose and that was 6mths ago. Saw it last week lockwire still very nice and taught. Hmmm
Jmac