Thermostat housing
Thread Starter
Cruising
Joined: Jan 2025
Posts: 13
Likes: 3
Thermostat housing
I’ve read that a lot of people have had issues with changing their thermostats, the seal ends up causing it to stick open. Is it the plastic housing causing these issues? I know the gen4 LT’s were a very similar design and we dropped 160s - 180s all the time a never had issues. I want to go with a 194 and billet housing. I know LMR used to be the go to but it doesn’t look like they make them for us anymore. What would you guys suggest/ have had good luck with?
Team Owner
Joined: Sep 2000
Posts: 25,015
Likes: 2,709
From: Far NW 'burbs of Chicago
St. Jude Donor '13
At 65k miles, our 2017 Z51 is on its third thermostat. They stick too much open, not closed; so it's not immediately dangerous.
There are enough similar stories to tell me that GM either bought a bad run of thermostats, or the current supplier is producing trash.
Most of the aftermarket thermostats are reported as even worse quality except Katech which are pretty expensive.
The engine is designed and programmed to run at the stock thermostat temperature, so I stay with stock temp.
But if the current one fails, I may switch to Katech if they make the stock temperature unit.
There are enough similar stories to tell me that GM either bought a bad run of thermostats, or the current supplier is producing trash.
Most of the aftermarket thermostats are reported as even worse quality except Katech which are pretty expensive.
The engine is designed and programmed to run at the stock thermostat temperature, so I stay with stock temp.
But if the current one fails, I may switch to Katech if they make the stock temperature unit.
Le Mans Master
Joined: Jun 2019
Posts: 5,481
Likes: 2,190
From: Loveland
I have never heard that they stick open because of the seal, they just fail open. I also don't think there is an issue with the plastic housing. You just have to be careful how you remove it. The small hose connection is easy to break. I suggest to get the entire housing replacement instead of just the thermostat. It isn't that much more and you will have a new seal and not kick yourself when you break the hose connection. YES, 194* is the correct temp for 2015 and up, 207* for the 2014.
Does Katech make a 194* stat? All I see is the 160* stat. Definitely not what to use for a non race car.
Does Katech make a 194* stat? All I see is the 160* stat. Definitely not what to use for a non race car.
Last edited by kodpkd; Nov 30, 2025 at 09:43 AM.
Drifting
Joined: Dec 2019
Posts: 1,814
Likes: 616
From: Blacksburg Va
Yep, I thought I've been working on cars all my life so why do I need the plastic housing. Then as I was putting the new t-stat into the housing my thumb slipped and it all flew 4ft and hit the concrete floor. Broke that small hose nipple right off. Ah crap. Plugged the hole in the housing and in the end of the small hose and it worked just fine until I got the housing and another T-stat in a week later. Now I have a spare new T-stat.
