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MG MGB Technical - Thermostat Housing..What am I missing?

Just started the 67 BGT after it was rebuilt. New housing for thermostat along with a new gasket and themostat. Gets warm and antifreeze actually seeps up the studs and dribbles out over the tops of the nuts. I really tighten down on the 3 nuts and still get some antifreeze. I dont remember sealant as part of the equation here? I actually had a second housing and tried that one with the same results. Would the cap pressure make a difference? Seems like I may be missing some obvious consideration. Gasket is perfect. For the antifreeze to run up those studs it has to be getting past a sealing face right?
R Stegs

The threads of the studs need to be sealed when installing. At least two of the studs go thorough into the water jacket. Cheers - Dave
David DuBois

Thanks Dave- Never thought about the bottom side of the studs....makes perfect sense now. Appreciate the response.
R Stegs

I made the same mistake. Well, not mistake, thing we didn't know we needed to know! I just undid the studs one at a time (using the two nuts trick), put some sealant on the threads and then reinstalled.

Now all I need to do is fix a weeping freeze plug and the slight leak around the fan switch in the radiator.
Simon Jansen

In addition to the above, avoid over-tightening the nuts - that could 'stretch' the lower stud threads and allow passage for coolant, under pressure, to work its way up. The nuts only need to be tightened to bring a sealing pressure against the gasket.

I wonder whether the stud threads in the head may already be 'stretched' to the point of being loose? The studs should not 'wiggle' when fully home. If those threads have already been damaged you could helicoil each back to the stud thread size for a firm hold.
Roger T

Over-tightening thermostat housing bolts can also warp the cover causing it to leak past the gasket. This can be fixed by patiently rubbing the sealing face of the cover on wet & dry or fine emery resting on a piece of glass.
PaulH Solihull

This thread was discussed between 21/08/2010 and 22/08/2010

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