I have never seen a thermostat housing like this. There is only one bolt. I got it apart but it will not go back together. It cocks when I try to tighten the bolt.How do you change a thermostat on a 1989 buick lesabre 3.8 liter v-6?Grease up the %26quot; O %26quot; ring at the bottom of the thermostat Housing with a Petroleum Based Grease Like Vaseline.
Twist the Housing left to right whilst pushing downwards on it until the housing mates firmly with the engine WITHOUT any gap , Then put the bolt in %26amp; tighten it up.
If that doesn't work , Replace the %26quot; O %26quot; ring and try again as it has likely swelled larger than the engines seating point.