Thermostat housing gasket not sealing

maxedstrom

maxedstrom

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Hey there I have a 2004 tj and I've been working on replacing the thermostat all weekend. I have properly cleaned the surface and I got a new thermostat housing as well. The gasket has been replaced 3 times and it has leaked every time. It has also been torqued to spec every time. I have been using a gasket maker and I'm starting to think that is the problem. Is a gasket maker unnecessary on the thermostat housing? Thanks for your help!
 
There’s a ton of threads on here suddenly about thermostat housing gaskets and leaking. Folks have done lots of different things to fix the leaks. No sealer. Sealer on one side. Sealer on both sides. Put housing on flat surface like a sheet of glass, then a sheet of sand paper, then smooth housing surface. One of the things new to me is one of the bolts is in the head and goes down into the antifreeze level. In this case you have to put some thread sealer on the bolt.
 
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TJ Jim said:
There’s a ton of threads on here suddenly about thermostat housing gaskets and leaking. Folks have done lots of different things to fix the leaks. No sealer. Sealer on one side. Sealer on both sides. Put housing on flat surface like a sheet of glass, then a sheet of sand paper, then smooth housing surface. One of the things new to me is one of the bolts is in the head and goes down into the antifreeze level. In this case you have to put some thread sealer on the bolt.
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so you're saying it's going up into the bolt and escaping through that
 
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Jerry Bransford said:
Mine wasn't like that but some have been. Definitely add a thread sealant to the bolt where the leak is coming from.
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the first time around I did and it still leaked but I did not add it for the second two. I'll have to give it a try. did you use gasket maker when you did yours
 
P man said:
Your thermostat is slipping down and interfering with the sealing surface
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the housing was leaking on my LJ when I bought it and this is exactly what was wrong.

I think I used some gasket maker to stick the thermostat in the housing so it wouldn't fall, but otherwise I think I just used a dry FelPro gasket and it sealed up just fine. It's paper but it's got these rubberized beads around the edge.
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maxedstrom said:
that honestly might be it. the gasket looks like its got a cut where the thermostat was every time I take the old one off
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Take a dot of rtv, grease or super glue and put a dab on the back of the thermostat and press and hold it in place for a minute then carefully install the gasket and housing
 
freedom_in_4low said:
the housing was leaking on my LJ when I bought it and this is exactly what was wrong.

I think I used some gasket maker to stick the thermostat in the housing so it wouldn't fall, but otherwise I think I just used a dry FelPro gasket and it sealed up just fine. It's paper but it's got these rubberized beads around the edge.
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that is perfect thanks so much for your help
 
Jack the front of the Jeep up when you replace the thermostat. That will help hold the new thermostat in place until you can get the housing installed.
 
Jerry Bransford said:
I never had enough trouble getting the thermostat to stay in position to think about jacking the front end up.
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Me neither. I can see how that problem could occur but can't say it's ever happened to me....also have only ever used paper gaskets as well. I will say once in the past I had hell getting my water pump to seal with just the gasket. Problem was radiator and thermostat were still on. Somehow they were keeping me from installing some aspect of that properly. once I removed them out of the way I had no more trouble.
 
I use sealant on mine and don't have any issues, obviously it isn't necessary. When you change it out just look down the threaded holes in the head. If they break into the coolant passages you need to seal the bolt, if not it doesn't matter. It helps to stick a flashlight into the space where the thermostat is and just look for the light at the end of the bolt hole. It is possible mine is the only one ever built that has this issue so I wouldn't get too crazy about it. I wouldn't ever recommend using something on the bolts, "just in case." If there is evidence of the thermostat slipping down onto the gasket that's the issue. There is nothing wrong with using a bit of RTV to help keep it in place, the Jeep isn't going to catch on fire or anything. I use a thin coating to tack the gasket to the housing as well. It just makes my life a bit easier.
 
Sorry for the dumb question, but how would you seal the bolt passage in case it communicates with the coolant circuit, threadlocker?
 
Not a fan of silicone or "greasy" sealants on a paper gaskets. A high-tack version would be fine. When you torque the bolts down, it may allow the gasket to squeeze outwards causing a separation in the fibers. I like the idea of a tiny drop of super glue to keep the thermostat in it's recess. I cracked two housings learning this the hard way (and inspect yours for a tiny crack barely visible). Housings are cheap.
 
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