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Home > Help Needed / General Tech Chat > Manifold to turbo nuts.

richminiturbo.

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Horndean - Near Portsmouth

20th Apr, 2010 at 02:18:31pm

Finally got round to swapping my manifold over today so I can refit the engine.

When undoing the manifold from the turbo the nuts were not tight at all!!

I'd used stainless nuts when putting it together in the first place, not sure if theyre the wrong nuts to use? I remember doing them pretty tight, the gasket has been blowing too thanks to the loose nuts, the engine has only idled for 10mins since I built it!

What nuts do everyone use on theirs? I fitted metal locking nuts to the elbow on my datsun which seem to be holding up fine.

What size is the thread?

Cheers

Rod S

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Rural Suffolk

20th Apr, 2010 at 02:26:42pm

I've used the original Metro ones as they (and the studs) are high alloy steel to withstand the heat.

The original Leyland studs are drilled for wirelocking which is unusual and makes me wonder if they had a history of coming loose.

The T3 on my Cossie uses the metal self locking type so I did think of using the same but they are a ridiculous price in the right material.

Thread is M10 X 1.5 (ie, standard ISO M10 coarse) both ends of stud but I have seen people mistakenly use 3/8"UNC - 3/8"UNF studs because the UNC end is very close to M10 (so screws into the manifold) and the UNC/UNF combination is a common manifold stud size on earlier cars.

Edited by Rod S on 20th Apr, 2010.

Schrödinger's cat - so which one am I ???

richminiturbo.

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Horndean - Near Portsmouth

20th Apr, 2010 at 02:41:51pm

Brilliant thanks rod!

Are you using any split washers or anything like that?

n.g.l.

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Chard, Somerset

20th Apr, 2010 at 03:02:23pm

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=182296

Make sure it's not the studs unwinding from the manifold and not the nuts vibrating loose. If its the studs no matter what type fastener locking you use it will still come loose.
I locked the studs into my manifold then I use nordlock washers under the nuts to secure the turbo. Has never come loose and have never burn out a steel gasket.
Dave.

Edited by n.g.l. on 20th Apr, 2010.


Rod S

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Rural Suffolk

20th Apr, 2010 at 03:04:28pm

On 20th Apr, 2010 richminiturbo. said:
Are you using any split washers or anything like that?


No.

One of the setups I got off eBay had a pair of linked tabplates (as well as the locking wire) so I've re-used those (but no locking wire). I don't normally use locktabs of any sort as they are usually so soft but there isn't any loctite that works in this temperature range and these locking plates seemed quite hard so I'm giving them a try.

Long term I will switch to the self locking nuts (as per the Cossie setup) but not until I've finished testing as they have a habit of chewing the stud up when you remove them.

Another thing I found is that one of the nuts can only be accessed by an open-ended spanner, not even a ring spanner ( because of the proximity of the turbine housing) so it is hard to get that one tightened adequately.

And finally, are you using the proper metal gasket. The proper one is high alloy steel with a deformable seal ridge. If you are using normal exhaust gasket material, or copper as some use, it may compress in service letting the nuts go loose.

Schrödinger's cat - so which one am I ???

tadge44

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Buckinghamshire

20th Apr, 2010 at 05:08:18pm

I used the linked lock tabs that Rod mentions until I had broken off all the ears. I now use spare std Metro nuts as locknuts.I have used SS ;ockwire but without proper lockwire pliers its too tough to wind up with ordinary pliers.

That fourth nut that Rod mentions is a right B###### to do up properly.
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