Review on 🌡️ Dorman 902-5000 Engine Coolant Thermostat Housing: Efficient Temperature Control for Optimal Engine Performance by Brad Ward

Plastic. It's reinforced where it should be and if you're not careful and use the wrong coolant like most people do, this part isn't going to rot like metal on you. OPINION. I like Dorman automotive products. I used to think they were crap just because their display cases were in every auto parts store I've ever gone to and that "usually" means they paid to be there and were of poor quality. Find out they really do go out of their way to make parts better than OEM. I called them one day to see if they made some different parts for my old Corolla and the guy on the phone said the parts they make wouldn't rot or break like the original parts. He was right as I could see where the parts I ordered had been reinforced to last longer and be more reliable. He also looked at some of the other part improvements I mentioned. UPDATE OPINION. Doorman now imports a lot of Chinese made parts so I downgraded their company to "potential crap".