Coolant on my bolts

[ianc9]

I've been installing a fuel injection system in my S1.5 and it got a little hot when idling (for some reason the fan didn't cut in) and the first issue I noticed was a small amount of coolant leaking from the cylinder head bolts.

I immediately stopped the car and realised it had gone into the red on the original temp gunge and the new ECU one said 118c.

I confirmed the temp with a beam thermometer.

No bubbles in the radiator.

I'm assuming cylinder head gasket has sprung a leak between the water jacket and the bolts -but not the cylinders.

I have open nuts on the studs rather than the fancy chrome dome nuts

Feck!

[ianc9]

I've been doing some googling on this and have found several mentions that the studs are actually submerged in coolant and that the seal is only made at the nut.

Is this correct?

Or am I clutching at straws...

[mgcjag]

Hi Ian....yes not a great design...on the later long stud engine the stud goes down through the head...through the hollow coolant area and screws into the bottom of the block....there is no "proper" seal through the head...the simple thing to try is a couple of bottles of Barrs leaks to seal the leaks....iv done this to cure the seepage under the nuts befor.....note that its not uncommon for these studs to snap due to corrosion at the base..this is always a risk if you undo a head stud nut so I would think twice if your thinking of removeing your standard nuts....Steve

[ianc9]

Thanks Steve :(
The engine was rebuilt about 3 years ago so studs SHOULD be ok. I have plain black nuts on the head (I think they were sourced from Denis Welsh.

The leak seemed to be coming up via the thread rather than around the bottom of the nuts (2 were doing this). So if my engine is one where the studs are surrounded by coolant then I might have a small problem which only manifests when it gets too hot and builds pressure. Or if I have an earlier engine - Then I have a head gasket issue. Right?

Do you know how I would determine if I have a long stud engine?

[mgcjag]

the earlier short stud blocks just have three large core plugs on the side and the later long stud blocks have five large core plugs along the block side ....

[christopher storey]

Your block from 1968 is likely to be a later long stud example. If your temperature reached 118C then the internal pressure will have been at a maximum that the cap will take and this will have forced water up the threads. Steve's suggestion of barr's is a good one - the factory always used 2 bottles on new cars !!

[malcolm]

I had the same coolant leakage on my ‘69 4.2 when I put the head back on. A bottle of Bars leaks sorted it, never had a problem since

[ianc9]

The magic Bar's shall be applied. Will report how I get on.

Thanks all for your insights

[ianc9]

Behaving so far - but now that fans are working it only gets up to ~98c max.