Morris Minor Owners Club

Hi all, it's been a while....

I've got a problem with leaking thermostat studs. I've done some work on the head, which has entailed removing the studs. On reassembly, I'm finding coolant is leaking up the studs. I thought it was because the threads in the head were full of crud and the studs weren't in properly, so I've had all 3 out, cleaned them, and dug the crud out, and I'm now happy that the studs are in the head fully. I'm tightening up the nuts to the 8lb-ft specified in the manual (mine is a 1275 ex-Marina engine), but 3 times it has leaked.
I've not experienced this before, nothing else has changed, apart from the gasket, which is now a grey card gasket from a well know supplier, rather than the thinner gasket that I've used previously. I've not needed gasket compound in the past, and I'm loathe to use it now. Has anyone experienced the same?

Cheers N

Yes very common...

Just use some hylomar or heldite sealant on the threads into the head and lightly grease the studs where they pass thro the alloy thermostat housing..

T

Thanks, good to know it's not uncommon. I may well go down the Hermatite/Hylomar route, though I don't like doing it, as it's a pain next time you remove the thermostat.
What's puzzling is why it's started happening, when all that has changed is the gasket.

Cheers N

The thermostat stud holes in the Marina 940 head should be blind, that is not drilled all the way through to the water gallery.
I suspect that the problem is your thermostat housing gasket.
Fitting a good quality thermostat gasket will in all probability cure your problem.
These are the thermostat gaskets I use:-

https://www.ebay.co.uk/itm/251750460431 ... %3A2334524

Lightly grease the gasket faces and smear copper grease on the studs. Both these actions will help with the sealing and any future removal of the thermostat housing.
If you do find that the stud holes are not blind use Loctite loc & seal on the threads or the sealants mentioned above.

Thanks Phil. I have tightened up the stud nuts a bit more, if it keeps happening, I'll do as you suggest.