Leaking thermostat housing

[armyman2014]

I’m having an issue with the thermostat housing. I have scraped off all of the old gasket, replaced the thermostat and housing with brand new parts and gasket. I used gasket sealer and let it cure but every time I hook the lines back up it spews coolant out of the bottom out of the housing. Any help is appreciated

Thank you all so much. I got the right stuff gasket maker and that did the trick and now she’s running like a champ

 

[Zorba]

I replaced my housing with a napa aftermarket housing and stant gasket. Could not get it to stop seeping coolant. Changed the aftermarket t-stat housing out for a MOPAR OEM unit and fel-pro gasket. No leaks. Did not use any sealant.

Doesn't that just figure. If I was still working, I could have taken mine to our machine shop and had them mill the damn thing flat. But as I don't, I didn't. How hard is it to not fuck up something like this? Good on OEM Mopar!

 

[P man]

Glad you got it solved but for future reference sometimes the thermostat will slip down and get wedged..it will really leak when this happens though

 

[hear]

Glad you got it solved but for future reference sometimes the thermostat will slip down and get wedged..it will really leak when this happens though

Came here to say this. And also that seems like the conventional wisdom is no gasket maker/RTV is generally necessary, but obviously the exceptions prove the rule.

First time I did my thermostat when I bolted everything up it leaked bad, but it turned out the thermostat fell out of the groove when I mounted it. It's possible you had that as well, and corrected it when you re-installed. The RTV may have not even been a factor in helping it seal up. No way to know now, but I guess it doesn't matter much if it's working.

 

[Wajeep]

Mine was a slow leak, not a "spew" - and it was apparently caused by a coplanarity problem with the aftermarket T-stat housing. The only way I was able to get it to stop was to use #2 Permatex in addition to the Felpro gasket - emery papering the housing would have been a very long chore - it needed milling and I'm not convinced the front of the head was flat enough in the right places either. If its "spewing", that ain't gonna work for long, if at all; there's a bigger problem.

I’m having an issue with the thermostat housing. I have scraped off all of the old gasket, replaced the thermostat and housing with brand new parts and gasket. I used gasket sealer and let it cure but every time I hook the lines back up it spews coolant out of the bottom out of the housing. Any help is appreciated

I had a similar problem. To fix, I used permatex in addition to the gasket. Then, I let it sit for 24 hours until I added coolant and re-started engine. There must have been a small scratch or something that wasn't getting sealed with just the gasket. No more leaks!

 

[Wattapunk]

I know that most say that no sealant is needed but count me as those that use some type of sealant on every gasket. I am a big fan of permatex ultra black gasket maker. That thing works for everything with gaskets that I have replaced with zero leaks. T-stat, water pump, oil pan. Heck, I even used it around the neck of my lower radiator outlet to seal a small coolant leak that a new mopar clamp didn't fix.

 

[mrblaine]

Glad you got it solved but for future reference sometimes the thermostat will slip down and get wedged..it will really leak when this happens though

Yep, that is the problem in this case. There is no leak that is spewing that will be stopped with a small bit of gasket sealer, that just isn't how it works. We always take a small bit of RTV and use it to hold the thermostat flange into the recessed area they are supposed to sit in. That way we know the flange isn't going to slip down and get between the housing and head and cause a spewing leak.

Regarding Charle's comment, OEM also has the sealer on the gasket.

 

[mrblaine]

Heck, I even used it around the neck of my lower radiator outlet to seal a small coolant leak that a new mopar clamp didn't fix.

Very common on old hoses with new clamps or just replacing the hose back onto the water neck after pulling it. If you don't get the new clamp or even the old one that is still good back into the same place on the hose, they generally will seep a bit.

 

[Winks42]

I’m betting your thermostat dropped out of the block when you put the housing over it, this is exactly what happened to me. I would recommend putting a tad of RTV on the thermostat on the outside so it sticks to the block better and doesnt fall.