Dorman 902-800 Engine Coolant Thermostat Housing Assembly

Got this for my 2007 Trailblazer with 6 cylinder engine. It fits, and works great, but it's a pain to install. I watched a few YouTube videos, and read a few posts in various forums before embarking on this "adventure". It's doable, and all ends well, but it's not what I'd call easy. I took the alternator off it's moorings, but left the wires connected and just shifted it as far forward towards the fan as I could. I jacked up the truck and took the drivers front wheel off. I drained the radiator by disconnecting the lower radiator hose from the radiator. I was able to access the top bolt on the thermostat from the top, but had to access the bottom thermostat bolt through the wheel well using about 20 inches of extensions on a 3/8" ratchet with a 10 mm socket at the end. You have to be careful NOT to drop any of these bolts...or you'll probably never see them again....they will fall into inaccessible locations. I took a thin (maybe 1/4" wide strip) piece of duct tape, and folded it over the end of the socket, half inside, and half outside, which makes the bolt head wedge into the socket...seemed to work for me. Once the thermostat was loose (both 10mm bolts removed) I actually removed the attached hose and thermostat as one unit. That allowed me to attach the hose to the new thermostat in the exact orientation/position it needed to be...easily, on my work bench, and not twisted around in the crowded engine bay. I then fed it back into place, and hooked everything up in reverse order of removal. To plug another product here.....for the past few years I've been using a vacuum filling tool when I need to drain and refill the coolant in my vehicles. It eliminates any air pockets in the system, and it's one and done...no adding another cup of coolant for the next week as you drive the car. I have the "UView 550000 Airlift Coolant System unit.... absolutely love it!

Well it's been three years and a month since I purchased and installed it. It just now went out last week. I'm giving it 5 stars simply because Dorman does warranty it even after this long... Amazon doesn't. Overall that's ok with me since it's worked great over the last three years and I'm able to get it replaced with the warranty through Dorman.

The Dorman 902-800 Engine Coolant Thermostat Housing Assembly is a must-have for any car enthusiast seeking reliability and durability. Its compatibility with select models ensures a seamless fit, saving you time and hassle during installation. Crafted with high-quality materials, this housing assembly guarantees long-term performance, even under rigorous driving conditions. The Dorman 902-800 and experience peace of mind knowing your vehicle's cooling system is in expert hands.

Lo utilizo en trailblazer 2003 4.2

Installed in 2003 Trailblazer with I6 - Fit 2003-2009 Envoy and Trailblazer Had check engine codes on fan speed high and low temperature. Replaced the fan clutch, water pump, and thermostat at same time. I highly recommend this for our motors. The fan clutch was locked and caused wear on the water pump. The thermostats are known to be junk in these motors. Having the thermostat stuck closed or water pump fail can cause a blown motor. Mine stuck open. Anyhow, the fan cluck stuck caused the water pump shaft to be warn. Having the fan out and the shroud made it easy to access the alternator so you can access the thermostat. Took about 2-3 hours or less to replace the fan clutch, water pump, and thermostat. If you have a failure of one of these items, replace them all at the same time. Look up on the internet for videos on how to do the work. I cut the fan shroud to go around the inlet of the radiator and made the job much much easier. You can do it and save big $$$$$$.

Worked as intended, exact replaement

Perfect fit,good overall product

I bought this thermostat in Sept. '25 and installed it in my truck. It's March '26 and it already failed. I'm very disappointed in Dorman for this. I use a lot of their products when I fix my cars and this thermostat cost me a lot more money and time than it should've to fix again 6 months down the road.

Quedo Perfecto, la calidad es de equipo original

Leider defekt, Thermostat öffnet nicht, daher unbrauchbar.

Ordered for an 02 Bravada. Was a perfect fit to replace the original and feels very sturdy. Came with o-ring and yes thermostat is in for those not clear and wondering. It's a one piece assembly. Make sure to clean surface properly without gouging and torque to spec and replace hose while at it. No leaks been in for almost five months now.

Pretty straight forward, perfect fit in my vehicle, and cleared my code(s). Be prepared for a huge mess of coolant when you disconnect everything, I had a tub ready. A drop cloth and a lot of folded/flat cardboard ready and it still made a pretty big mess. I poured kitty litter over everything that I couldn’t soak up, then swept it dry the next day, and it perfectly got rid of every drop.

Good product not the easiest install