Thermostat Leaking on '88 Jeep Cherokee
 

Hello there,

New to the forum! I have a 1988 Jeep Cherokee Pioneer. I have seen a couple of threads on this topic, I have never had to deal with a thermostat in the position it is on the 4.0 litre, I have had GM vehicles where thermostat is right on top of the intake manifold. I have replaced the thermostat gasket twice already on my cherokee. I've replaced the housing once. Yet somehow I am still getting a leak at the bottom of the thermostat. I use a typical gasket sealant on the gasket and the housing surface and am still getting a pretty good leak. I have heard peope say that you shouldn't have to use sealant at all. The only thing that I can think of that I am not doing correctly is tightening the bolts to the correct spec. I think it is 15 lbs. I go till the bolt gets tight, then I turn another half turn and call it good. Does anyone have a foolproof way of making sure there are no leaks? Is there a specific sealant that works better than others? Should I use a sealant at all? I am so tired of dealing with this and then I have to burp the damn system because it is closed after every time, it is such a pain!!! It only has 76000 miles on it.

did u make sure to clean both mating surfaces? i usually us rtv and a gasket just to make sure i dont get a leak. i dont like doing things twice. permatex gasket maker works pretty good.

The next time you pull it off make sure that there isn't any pitting where the gasket mates up.

Ok I'lll try the permatex, and yes both surfaces were spotless. I didn't notice any pitting on the housing but jeez I might just get another one to be sure, it was only $15. Is it ok to put a little bit of gasket sealant on the thermostat to help it stick to the block while I am putting the housing back on?

I am going to try again next week, I will let you know how it turns out, I bought one of those fail-safe thermostats that stay open if they ever fail, is that an ok thermostat to use? I've heard different things.

Not too sure on putting gasket sealer on the thermostat itself since it may interfere with the coolant. Having a thermostat stay open if it fails will just not let the engine heat up very quickly and it would have trouble keeping normal operating temperature. You may end up overheating eventually because the thermostat cannot open and close to regulate the coolant temperature. I say get a normal thermostat like they came with from the factory. Run a 195 degree one.

Ill throw my 2 cents in here, so when you take the thermostate housing off again, make sure you clean off both sides that will touch the gasket. I usually take off all the old silicon with my fingures and then take a flexable putty knife or a replacable box cutter blade and run it along the surface to make sure its level. After both of those surfaces are as smooth as I can get them, I start putting everything back together. If you want to get a sweet awesome thermostate, then get the Stant SUPERSTAT for the jeep cherokee. I have heard great reviews and personally can say it regulates my temp alot better then the oem replacements. Once you get your thermostate I put a small dab of silicone on either end (3 o'clock and 9 o'clock) to secure it in place while I do the rest. Then I take Permatex Ultra Copper Silicone and dab it over all the contacting surfaces of the motor side of the gasket and then the contacting surfaces of the thermostat housing. Once all that is done, I stick the gasket onto the motor with the silicone surface against the block and then take the thermostate housing and put it on top. Put the bolts in, torque them down to what my chilton manual says, and then your done. So far I havent had a leak. So Id say make sure your thermostate is staying in place, make sure your contacting surfaces are clear of debree, and also make sure the thermostate housing contact surface isnt warped. I got a housing off of a 91 xj for my 90 xj and had to file the contacting surface down because it was slightly warpped. Sorry kinda wrote a book.