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.

Fit me 2015 sierra 6.6

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)

For an LB7 (early 2000's) Duramax, you need two different thermostats that fit in the same housing. There is no traditional housing gasket--the thermostats have a rubber gasket around their circumference which acts as a gasket. I've had this truck since new, 13 years now, and it has never gotten near normal operating temp when the ambient temperature is below about 50 degrees F. I swapped in these thermostats and now the truck quite quickly gets close to summer engine temps even in ambient temps of the low 30's, which is about as cold as it gets here.The thermostats are not marked AC Delco, but they look identical to the factory parts and work better, so I am happy.

Works

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.

I was driving around my LB7 Duramax for years with the thermostats stuck open, the truck never warmed up LOL. Finally I replaced it with these, wasn't too bad of a job and the fit was good, the truck warms up like it should now.