Leaking Thermostat Housing after Thermostat Replacement

2005 4.0 V6. Attempted to replace my original thermostat with a new one, installed the part, tightened down as much as I could, and now the thermostat housing is leaking from the bottom. I thought my bolts may have been a tad loose, so I started to tighten one, and ended up snapping a bolt. What gives? Unsure why the leak could be happening if anyone has any clue. Any help would be greatly appreciated.

 

Take a really close look at the housing. There is a good chance that it is cracked. You will most likely have to take it off to find a crack. Or pinched the gasket.

 

As the housing and thermostat are a complete assembly, the only obvious answer would be a defective or pinched seal. When you attempted to tighten it, you said you snapped a bolt. I assume you mean you snapped a stud as the water pump in the service manual shows three studs and nuts that hold it in place.

 

I will take a look first thing in the morning. I hope it is not cracked..

 

I apologize, I meant a stud. I’ll check for the pinched seal. I was sure I put it on correctly but it may have slipped.

 

You didn't use a torque wrench? Torque on the housing is 80 ft/in, or about 6.5 ft/lb.

 

Solved. The oreilly Murray thermostat I used was the culprit. The design must be a hair off compared to the OEM Toyota Thermostat. Switched out the Murray for the Toyota, and truck was fine like nothing ever happened. Zero leaks. That’ll teach me to buy OEM.

 

What became of the snapped bolt?

 

With all due respect, I'm more inclined to believe the thermostat was not installed correctly the first time. I have 60K miles on a Gates thermostat and Murray has been around for a while. Good to hear the truck is rolling.

 

If the stud goes to hell spray it with wd-40, wait a few min, tap it with a hammer, then use death grip on vise-grips and remove. Replace with a bolt if necessary. That's what I did when installing my 170* urd thermostat.

 

I do have to agree with you. I’ve used several Murray thermostats in the past and all have been working fine, but for some reason this Thermostat was just not doing its job. Not sure how rare it is to have a bad part, but it may have been. Took off the Murray four times to make sure the O-Ring was properly seated, and that it was installed correctly, and it was.. I’m just glad there is no longer coolant spilled everywhere.

 

Yep. Exactly what I had to do. Replaced with bolts.