awork

I have a 97 jeep Cherokee. I changed the thermostat a couple weeks ago. it took 3 gaskets before I could get it to seal up all the way. It was good for a week and I got home from work and my wife noticed a few hours later there was a puddle under the jeep. It was a few days before I was able to check it out. By then I could not find any evidence of where the leak was coming from. I refilled the antifreeze and let the jeep run for approximately 10 minutes then drove it and let it run for another 15 or so. Not a drop. I have drove it the last couple days and it still had not leaked. This morning after driving it to work I noticed when I came out there was a puddle under the jeep again. I couldn't find any place where there was a fresh leak. I am not 100% sure it was from mine this time but it was for sure antifreeze on the pavement. Drove it home and put some cardboard under it all day and not a drop. Any ideas where this could be coming from? The gasket doesn't seem to be leaking but I am not sure. If it was I would think it would leak consistently not just every few days.

Thanks for the help.

md21722

If it took three gaskets, the aluminum thermostat housing is probably warped. You can buy them for about $10-15. You need to get under the Jeep and look up. The water pump weep hole on the bottom may be leaking. When it does it often ends up dripping off the lower radiator hose. You might have multiple leaks. Make sure your hose clamps are tight enough. Just don't over tighten the ones on the radiator or you might break the plastic necks.

Radi

Most auto parts places will loan/rent you a cooling system pressure tester. Pressurize the system up to the cap rating and watch for leaks.

awork

Well the reason the first 2 didn't work was because I believe I had put them on wrong. The last one started off good and then after some driving was spraying a small stream out of the top right of the thermostat housing. I tightened the bolts a little more and it stopped. That is when it went over a week with no issues. I will double check all of the clamps and the water pump today.

Also if I can not figure it out I will see about renting the pressure tester too.

Thanks

awork

Ok so I don't know if it is coincidence or what. When I drive it and it sits inside all night it doesn't leak. But when I drive it and it sits outside it does. What would be the reason for that?

djb383

That's called a "cold leak"......it's quite common. Parts expand/contract over heat/cool cycles. Sealing surfaces that have a borderline seal expand/contract/move thus allowing a leak. U need to get it fixed asap because when u see coolant on the ground, that coolant that was inside the motor has been replaced with air inside the motor. Air in the cooling system is not good.

awork

Hmm. Would that be caused from the gasket not sealing up? I am thinking about replacing the thermostat housing. The local parts store has a dorman brand and compressor works brand.
Also I have been using gasket sealant and that has not helped. Should I try without sealant? What should the bolts be torqued too? I plan on renting a torque wrench this time.

awork

Would cold leak be caused from a bald seal on the gasket? I think I am just going to replace the thermostat housing since I keep having issues. The local part store has dorman brand and compressor works. Which is better? Also should I not puy sealant on it this time? I plan on renting a torque wrench this time, how tight are the bolts suppose to be?

djb383

R u positive both sealing surfaces (head & cover) r sterile clean/perfectly flat? There is a grove/recess on/in the head that the stat sits in.....is the groove/recess sterile clean? Clean the bolt threads and hole threads as well. A dab of grease/oil on/in the threads never hurt anything. Sometimes the stat will fall out of the recess, when the cover is installed, causing a bad seal. The stat goes into the recess, then the gasket goes on top of the stat. Use a thin film of water pump RTV on both sides of a new gasket. If u've done every thing correctly, the bolts should be just snug.....not cranked down hard.

awork

The last gasket I put on I made sure everything was perfectly clean. I took sand paper to the flay surfaces and used a small drop of rvt to ensure the thermostat stays in place. It looks like the leak is coming from the top on the right side.

djb383

R u positive the cover is not cracked?......hairline crack can be hard to see.

awork

Well I am not sure on that. That is why I am considering replacing it. It looks like the antifreeze has been coming out from around the gasket though. I am not sure if a crack would cause that?

djb383

What appears to be coming from a gasket could be coming a crack. Wouldn't think 3, or is it 4, gaskets would all be bad.

awork

This one is the 3rd one. But the first one I put the gasket on wrong and the second one I think the thermostat didn't stay in the right position.

djb383

If everything was done right the 3rd time, then I'd suspect a bad cover.