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
Leaking thermostat housing
- Thread starter armyman2014
- Start date
First check the easy things....
Verify the heater hose is not leaking between the hose and the housing nipple.
Ensure the clamp is properly tightened.
IF you are using the factory constant tension clamp; it may have lost its tension (I had that happen).
IF that is not your problem; then inspect the housing for cracks...
IF no cracks are observed; then you will need to remove the thermostat housing and verify the head and thermostat housing mating surfaces are thoroughly cleaned and there are no gouges in the the thermostat housing surface.
Make sure the gasket has not become misaligned when bolting the thermostat housing.
Verify the heater hose is not leaking between the hose and the housing nipple.
Ensure the clamp is properly tightened.
IF you are using the factory constant tension clamp; it may have lost its tension (I had that happen).
IF that is not your problem; then inspect the housing for cracks...
IF no cracks are observed; then you will need to remove the thermostat housing and verify the head and thermostat housing mating surfaces are thoroughly cleaned and there are no gouges in the the thermostat housing surface.
Make sure the gasket has not become misaligned when bolting the thermostat housing.
Spewing out of where the thermostat housing is attached to the head? If so my bet is there's still a small shard of the old gasket left on the head or housing. Or if it's a new housing and you have triple-checked the head's gasket seating surface for being surgically clean of even the smallest iota of the old gasket, perhaps the seating surface of the new housing isn't as flat as it should be. Not all have perfectly flat surfaces and sometimes have to be made flat by placing suitable emory cloth on a flat surface and run the thermostat housing around on it until it's flat.
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.
Check to see if the flange on the new housing has the same thickness as the flange on the housing you removed. The bottom bolt could bottom out in the head before seating the flange if the new housing flange is thinner.
The Right Stuff 1-Minute Gasket Maker Black.
It costs about $35, but it is so worth it.
I went through 2 Fel-pro’s and 2 other brands with/without permatex RTV. Nothing.
First attempt with The Right Stuff and problem solved. I’ve done diffs and TCases and it always works. Literally 1-minute. No waiting time. Stop wasting your time and just do it. It saved my life those 2 days I tried to seal the thermostat. I thought I was going to go crazy.
It costs about $35, but it is so worth it.
I went through 2 Fel-pro’s and 2 other brands with/without permatex RTV. Nothing.
First attempt with The Right Stuff and problem solved. I’ve done diffs and TCases and it always works. Literally 1-minute. No waiting time. Stop wasting your time and just do it. It saved my life those 2 days I tried to seal the thermostat. I thought I was going to go crazy.
The bottom bolt hole on my Jeeps thermostat housing goes through the block into the coolant passage from the factory, if you don't use sealant on the threads it spews coolant out of the threads because the gasket does not seal the bolt hole. On my Jeep you are required to seal this bolt, maybe that's your issue, maybe not? It isn't easy to get the gasket lined up and everything sealed, that may be the problem as well.
Old_Crow
TJ Enthusiast
When I had my shop, I had a wing window from an old Chevy Truck laying around. I used to stick a piece of 180 long board paper to it and true the surface of the t/stat housing before I reinstalled it. Between that and good old Permatex #2 I never had a leak.
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.