ACDelco GM Original Equipment 131-131 Engine Coolant Thermostat

Identical replacement to the one that came out of my 2002 Chevy 2500HD Duramax. My original thermostat got stuck open, so it would take 30+ minutes for engine temp to get up over 165 degf, which is too cold for this engine to run. Once swapped out with this one ( and also swapped out the other thermostat - there are two thermostats side by side under the same housing in this engine, one opens at 182 and the other 185 degf), engine got up to temperature like it should in 10 minutes or so.Changing this was fairly easy. I drained the coolant by removing lower radiator hose (there is a drain Petcock on the bottom of the radiator, bit after breaking a few of these on other vehicles, I always just pull the lower radiator hose). Pulled intake resonance chamber, alternator positive cable, and unplugged a few wiring connections. After that, was able to pull thermostat housing, scrape clean with razor blade, and out back together. You don't need any gasket on the thermostat housing - rubber thermostat gasket supplied with parts is all you need.Refill coolant 50/50 dexron and distilled water then bled air out of engine block (there is an air bleed bolt on top of the thermostat housing you can use to do this). After air bled, started engine, let warm up until thermostats opened ( can feel upper radiator hose get warm). Once thermostats open, it will suck down about held the coolant reservoir, so make sure it's full.All in all, easy job. Took about 4 hrs. Fixed the issue.

This was for my 2012 Duramax Diesel and is the rear thermostat in the thermostat housing. This is a 180 deg stat and the front one was 185 deg. I was unaware I had a problem until the truck set a code for low engine temperature. When you change this thermostat you need to change them both. This product came in a unmarked box with GM numbers on the top. It fit and looks like the OEM and so far is working fine.

good replacement

I read enough bad reviews of the off brand thermostats that I decided to stick with GM original equipment. Pay attention to the orientation when installing. Very easy job to do yourself and save some money. Temperature stability has been perfect since I changed both thermostats.

OEM replacement for my 2004.5 LLY Duramax Diesel engine. Operated flawlessly at the appropriate temperature.Don't forget there are two different thermostats needed! (Other ACDelco thermostat needed Part #131-163)

Works

Fit me 2015 sierra 6.6

Worked perfect. Our GMC wouldn't warm up(bad in the winter, no heater). I checked the t'stats and the rubber seal was partially missing. That didn't seem like it was causing all the problem but I installed these anyway. Warms up to correct temps now. It's not a hard job to change them, just have a container big enough to drain the coolant into. I misjudged and had to close the petcock and find another container to catch the remainder.