Detroit Thermostat Location

follow the top rad hose back to the head and there in that housing

 

There's two I recommend whatever stock temp is, if colder the engine will stay in warmup mode and use fuel. Drain coolant, remove hoses, remove housing (four 15mm bolts that need 50 lb ft when putting back. Remove housing and two thermostats. Remove the two seals by pushing the at one point deeper into the housing, you have to crush them some to be able to pull them out. New seals I used a large socket (1 3/16 or something) to drive the new seals in. The rest is pretty straightforward. Hopefully I didn't forget anything. Try to do anythig else that requires drained coolant.

 

It's actually pretty easy. I have the service manual in PDF format and could give it to you likely Saturday.

 

S60's are one of the easier ones. The hardest part is getting the seals in straight without damage, just take your time. There is no housing gasket or sealer used to seal the housing, the thermostats have a rubber lip that seals to the housing. Make sure everything is clean to avoid leaks. I put a thin wipe of grease on the housing to help keep it from rusting where it's just metal to metal.

Depending on the chassis, you may have a bleeder in the top rad pipe. If you do, have it open while refilling the antifreeze. Once coolant comes out the bleeder, close it and finish filling. Run it for about 5 min with the radiator cap off, then open the bleeder again to get any trapped air out of the pipe, top off the radiator and put the cap on.

 

Can I put little sealer around the housing?