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MG MGA - Thermostat housing

Just changing my thermostat housing.
I was surprised that the diameter of the thermostat is greater than the diameter of the aperture in the gasket. I’m assuming that’s normal.
So I am assuming I should put it back the way it came out, which is dropping the thermostat in first and then bedding down the gasket on top of it?

Seems the only logical way to do it but I was surprised the gasket will not sit flat.
I intend take do my usual belt and braces approach and use holymar blue; I realise some may not be a fan but I like to use it.
Graham V

Yes, thermostat in head, gasket next then housing.

I'm with you about adding a non-setting sealant to avoid coolant leaks and if there are leaks you can nip them down.

But I much prefer the semi-hardening (Hylomar) Hylotyte Red 100 on the coolant gaskets. - https://hylomar.com/en/hylotyte-red-100/





Nigel Atkins

Nigel

Is the Hylomar Red same as/similar to the good old Red Hermetite?

Cheers
Dave
Bolney Coupe

Graham. I agree with Nigel, except that for something over 50 years I have used the Permatex "Aviation Formula Hi-Tack" cement, another non-hardening gasket sealer. I suspect that the exact sealer used is rather unimportant.

Les
Les Bengtson

Dave,
IIRC yes, AFAIK as I looked up the details before, probably the details are in one of the model Archives on here.

Les,
if the sealant works it doesn't matter but it becomes more important when it doesn't, I used Universal Blue on the gasket of my heater tap pedestal to cylinder head gasket and it leaked, used Red 100 instead and it didn't leak.

I almost put in my last post, last time I fitted my stat housing I had just started to apply the Red 100 when a summer shower started so I speeded things up as I was getting wet and latter I got a coolant leak from the gasket area, possibly not tightening the nuts enough before but I only needed to nip the nuts up to permanently stop the leak. I use 4-Life coolant that will find any means of escape.

Possibly Permatex "Aviation Formula Hi-Tack" cement is even better than Red 100 I don't know as until now I'd never heard of it let alone used it but I have been using the Red 100 successfully for quite a while now and unfortunately have had to take things apart on the cooling system for various reason far too many times than I should have needed too and certainly wanted to so I value things that actually work as they're supposed to.
Nigel Atkins

Thanks v much for the feedback.

Nigel, I see you prefer “Red” to “Blue”. If I use red, what should I expect if I have to open it up again, eg if the thermostat fails.
Should I expect to have to scrape the red off. The blue comes off very easily but I guess that may be why you find red seals better.

Thanks
Graham V

Graham,
I can't remember either being difficult to clean off (but then my memory isn't the best) I should have put I don't bother trying to clean a paper gasket I just replace those with new. The red IIRC was just a wipe off the metals, I can't remember what I used but it was only whatever was to hand in the shed. I usually apply the red with a very cheap artist's brush from a very cheap set.

I didn't apply any sealant when I used the Klingersil gasket on the stat housing but I found that gasket left part of itself imprinted on the stat housing particularly so I went back to a higher quality (! cost more anyway) paper gasket and used the red. HTH.
Nigel Atkins

Thanks Nigel.
Graham V

This thread was discussed between 01/05/2022 and 03/05/2022

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