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ok ive looked on line and ever where else for the location to drill the 1/8 hole in my thermostat.

?- where the correct hole location
?- read where theres a gasket between housing and thermostat, where do I find one?. my new thermostat's did not come with it.

?- I've got an 160 and 170 degree theromsat which one should be used?

thxs.

That's an old timers trick when they run the engine too hard and hot and want the thermostst to bypass a bit of the trapped coolant. You already have a bypass hose on the top of your waterpump for that purpose so drilling is not necessary.

The thermostat manufacturer normally carries a gasket to fit all their applications. If not just ask your parts store clerk for a housing gasket for a 1965 Jeep CJ5. Is your thermostat spacer in good shape?

ive got a thermostat housing gasket. im referring too (what ive read) is a rubber gasket that's mounted between the flange on housing and the thermostat. when I ordered the kit all it came with was the thermostat, gasket, and retainer. for the m38 l134 engine. thxs

That's the only three pieces I have ever put in one. Who told you you needed another 4th piece made of rubber?

This is all you get:



Here's the M38 blowup.

PostPosted: Fri Dec 16, 2011 10:14 pm Post subject: Reply with quote


The retainer holds the thermostat in the upper part at the top of the housing. There should also be a gasket on the upper ledge that goes above the thermostat. The whole thing then bolts to the head with another gasket there. Make sure you have a 1/8 inch bleed hole in the thermostat which equalizes the antifreeze on each side so it doesn't have a air bubble there. Strange setup, but that's the way they are! Laughing John

w esk, no one told me.

I did a google search to figure out the thermostat was placed into the housing. and this is what I saw that was discuss on this forum.

Then tell me the part number of the upper seal. There is no such creature in the M38 and M38A1 parts manuals nor in the 49-55 Willys Master Parts Manual.

And I say again no bleed hole needs to be drilled in any M38 or M38A1 thermostat. The bypass hose between the head and the water pump handles the bleed issue on the M38 & M38A1. The CJ's that came without factory heaters came without the bypass hose. That's where the hype for the bleed in the thermostat came from.

I have never put any gasket other than the one that goes between the thermstat housing and head, on any of the Jeeps I have done. Never heard of anything going above the thermostat.

cant give you a part number, while searching about the housing, the above statement was found about the seal. i'll install per diagram. thxs

Here's the thermo installation for my M38. NIB - no upper gasket, only the housing-to-head gasket (not shown in the pic). Thermo flange has lettering stamped in the metal "this end towards radiator" so that end is "up" and I seem to remember the flange already had a hole but its not visible in the pics.

thxs skyjeep for the pics. upper thermostat housing that i have does not have the hole. but i'll installed per diagram and not worry about the hole. thxs