Potential leaking stud on engine block - cures?

[Colin Lindsay]

This is a scenario I'm going to try to pre-empt by asking in advance - I had a stud broke off in the engine block at the weekend, the one that holds the timing cover on and goes right through into the water jacket round the block. I had to drill it right out - no give at all, even the last millimeter of stud held firm. I've retapped the hole but I'm concerned that there is a slight unevenness around the new stud I've tried in it, so am wondering what anyone recommends to seal it before the coolant starts to escape when the engine runs up to full heat? It may seal tightly enough on it's one once fully tightened but it may also weep later, so I'd like to treat it in advance. I've got JB Weld and Araldite and such like but I'm wondering is there any other sealing product that members would recommend whereby I can just dip the stud in, screw it in, and forget about it? (No intention of removing it again in the near future!)

 

 

[RogerH]

Hi Colin,

protect the thread with Welseal etc to slow down the corrosive powers of the coolant (if there is any).

There is a gasket between cover and block - so that should not leak.

Coat both sides of the washer under the nyloc nut with Hylomar.

 

Roger

[Nigel Clark]

How loose is the stud in the retapped hole?

If it's still fairly tight, not too wobbly, I would use Loctite.

If it's not so secure, try Araldite as it will fill the gap better, but go for the standard version (not fast cure) and give it plenty of time. It will be stronger in the long run.

Nigel

[Nick Jones]

Usually use Loctite lock 'n seal here.  It works.

Nick

[Pete Lewis]

loctite 573/ 574   used on truck production to solve all gasket. stud leaks and suck like 

still got a couple of cartridges left after they closed production down  ,  magic stuff 

pete

[poppyman]

I would use JB weld original Colin to dip the stud in, and then screw into block. Then as above hylomar around gasket and nut/washer it wont leak then......... ?? I would chance it on a car of mine.

Tony. 

[Colin Lindsay]

Thanks for the suggestions team, it doesn't wobble at all and is quite a tight fit but I'm still worried about potential seeping. I don't want to have to take the timing cover off again and disturb anything. Loctite I have - the permanent version should work ok?

[RogerH]

Hi Colin,

if the thread is dodgy consider using a helicoil.  This will tight against the block and the stud will be tight against it.

 

Roger

[Colin Lindsay]

The thread's okay Roger, in fact it seems to have tapped out the remains of the stud as well as the original block drilling. It looks slightly 'coned' due to the drilling but it's micro-millimetres if anything. I've never seen a stud hold fast like this one - you can see all the drilled swarf round about in my top photo. It was solid, and even the remains would not drop off the block when fully drilled. I've tried a replacement and once it screws in as far as the collar it looks as good as original, but as usual I'm being mildly paranoid so going for belt-n-braces approach.

[68vitesse]

Resurrecting old thread as seem to have plenty of time to work on the Vitesse.

Have had a very slight weep from the front stud of the exhaust manifold, removing it and using gasket sealer only works for a while stud is a bit wobbly as old one needed drilling out. Even made a new stud from a bolt cutting the threads as shallow as I could to try and give a better fit. Current plan is to remove water pump assembly to give access to inside of stud hole drill out hole, before removing manifold if possible, then helicoil it. Bought the bits a while back never used helicoil before does anyone see a problem with this plan.

Don't want to repair to destruction as only very slight weep.

Regards

Paul

[Pete Lewis]

its worth a try going up a size or use coarser metric equivalent    as an idea 

me i would use loctite 574 on the threads  this stuff goes hard when air is excluded    its a life saver sealer 

Pete

[dave.vitesse]

56 minutes ago, 68vitesse said:

Resurrecting old thread as seem to have plenty of time to work on the Vitesse.

Have had a very slight weep from the front stud of the exhaust manifold, removing it and using gasket sealer only works for a while stud is a bit wobbly as old one needed drilling out. Even made a new stud from a bolt cutting the threads as shallow as I could to try and give a better fit. Current plan is to remove water pump assembly to give access to inside of stud hole drill out hole, before removing manifold if possible, then helicoil it. Bought the bits a while back never used helicoil before does anyone see a problem with this plan.

Don't want to repair to destruction as only very slight weep.

Regards

Paul

Were possible I have re-taped with metric, if not then used helicoil for similar jobs without any problems. I agree with Pete also use a sealer.

Dave

[Colin Lindsay]

1 hour ago, 68vitesse said:

Bought the bits a while back never used helicoil before does anyone see a problem with this plan.

Don't want to repair to destruction as only very slight weep.

As an expert on repair-to-destruction I'd reckon that helicoiling a thread works well; I bought a kit a year or so ago for the Tr7 with those strange metric fittings and once you have the initial expense of buying the tools - about £27 iirc - then bags of coils are very cheap, so you can find the original imperial size for the same stud if needs be. It's quite easy to do once I watched an engineer do it for the first time (I passed the buck!) then tried it myself ever since. I also bought a tube of Pete's highly-recommended Loctite 574 as a back up.

[68vitesse]

Still need to do this job but did not have any head to pump housing gaskets, made these this morning from 0.4mm Flexoid paper using a spare head as template. The kit is not a Helicoil only name is Hot-Sale still wondering if best left alone till lockdown ended.

Regards

Paul

 

[Peter Truman]

I would suggest If you use the Helicoil ensure the insert coil isn't too long as you are going thro into the water jacket and if too long when you come to snap the tag off it could be in air resulting in the retapped helicoil jumping a thread which would stop the stud going all the way through, don't ask how I know!

You can buy replacement Helicoil inserts of different lengths, and as stated there relatively cheap.

I've successfully used Helicoil or Recoil for years of all different sizes, just take you time don't force the coil down the thread just rotate nice and slow let it wind itself in.

Peter T

 

[poppyman]

2 hours ago, 68vitesse said:

Still need to do this job but did not have any head to pump housing gaskets, made these this morning from 0.4mm Flexoid paper using a spare head as template. The kit is not a Helicoil only name is Hot-Sale still wondering if best left alone till lockdown ended.

Regards

Paul

 

I have just come in after using a similar kit on my Stag stromberg carb with great results. Just thought i would give it a try. It was a cheapo kit off fleabay £4-99p. Bargain.

Tony.

[ahebron]

I have trimmed helicoil lengths down, obviously not at the tang end😉

Last time on the Vitesse was when I was fitting the body and the thread for the bolt on the rh axle hump stripped.

[Colin Lindsay]

Sad to say I haven't got that far yet, even despite lockdown.. the freshly bored block is sitting under bubble wrap in a corner of the garage, refurbished head beside it.

Helicoiling is certainly an option, but then so it fitting a new stud with good threads for that extra bit of bite and sealing it in place with Pete's highly recommended sealer.