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Thermostat: Gasket Needed?

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62BT7

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All: I know, the title should provoke a "Well of course, dummy..", but here's the issue: I'm overhauling the cooling system this week and of course a new thermostat is on the menu. I pulled out the old one, a "wax type" ie non-bellows version (fyi, I have a '66 BJ-8 engine [29K] in my '62 BT-7). It had a standard type of gasket which I of course scraped off. I'm interested in trying a bellows type thermostat and bought the Moss version just to experiment. Question: The gasket that is recommeded, and which is pictured in the AH shop manual as a "joint washer," is a very thin diameter ring about 2" across or so. Not a usual paper type gasket. Seems like the little washer allows the therostat housing to rest right on the cylinder head, ie metal-to-metal contact, but slipping a standard gasket in means the bellows thermostat will not fit in at all, and it fits poorly on top. Should I rely on the joint washer and seal the housing with Permatex? Use the washer and a paper gasket (which is not mentioned in the shop manual, btw..)Recommendations? Many thanks,
-Tom
 
The thin circular paper gasket goes between the head and thermostat. You still need a gasket between the t-stat housing and the head.

I can't recall the last time I saw a Healey in service with the bellows thermostat (even during my tenure at Austin-Healey West) so I can't comment on the gasket fit around it.
 
Hi Tom, There are two joints [Washers] involved. One small circular joint goes between the head and the thermostat. the second joint goes between the head and the out let elbow. If either is missing they can be made using the cars fittings and lightly tapping them to shape with a small ball pean hammer.---Fwiw-Keoke.
 
What happens if you do not use the lower gasket, the one between the thermostat and the head? Is there much bypass leakage? BCS once told me that they also used o-rings instead of the thin paper gasket.

Mark
 
Yes Mark, it is possible to use an "O" ring instead of the small circular joint but may apply undesireable pre load on the out let elbow. Not using any just may let the thermostat float producing some additional bypass flow.---Keoke-?
 
Hi Keoke,
The thermostat I bought at Moss a couple of years ago was a tight fit with the lower gasket in place. I just recently replaced it with a thermostat from BCS and it seems to fit a little better, and the BCS unit would take an o-ring a little easier (but I still used paper).
Thanks,
Mark
 
Apologies for reviving an old thread, but I've searched the forums and can't find any information about bonding this thermostat gasket (Moss 296-300) to the head and/or the sleeved type thermostat. I'm a new BJ8 owner and just flushed the cooling system and rebuilt the heater, and I want to be sure I install the sleeved thermostat correctly. The gasket is the standard flimsy cardboard affair, and I don't see it lasting very long in the coolant flow without some serious adhesion. Do I use permatex to attach the gasket to just the thermostat or to the head as well? Looking into the head from the open thermostat housing, it doesn't appear there is a firm seat for the gasket, and as there is no way to check the gasket once the thermostat is seated, I have one shot to get this fit correctly. Appreciate any and all advice.

-Chris
 
If I have one, I just drop in the small step in the head; if I don't, I don't bother. No big deal either way (it's basically a piece of thick paper that turns to goo after a few minutes' running).
 
Yes use a sealant to instal the gasket.
 
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