How do you replace a thermostat on a 2000 Volvo s40?

Answer 1

Drain coolant enough to at least empty pressure at top radiator hose. Save coolant in a container. The thermostat housing is located on top of the engine, of passenger side where the top radiator hose is clamped. Use a T-40 torx drive socket to remove the two bolts, be careful you don't damage threads. Remove the housing then remove old thermostat. I recommend replacing coolant temp sensor at same time, it is located underneath thermostat and is threaded into the thermostat housing. Both parts together will cost about $80-85 from your Volvo dealer. (Volvo Thermostat part # 271664, Volvo Coolant Temp. Sensor/IAT Sensor part # 9125463)

Use sealant (Water Pump & Thermostat Housing RTV Silicone, cost around $3) around match surfaces of housing with new thermostat in place. Carefully seat the housing and carefully thread the mounting bolts to seat the housing. When a little sealant escapes around the edges and bolts are tight STOP, do NOT over tighten. It doesn't have to be torqued on there the sealant will heal around the surfaces and bond the mount in place.

Reconnect sensor and reconnect top hose.

If you are going to drain the system, remove radiator drain plug it's located there at the passenger side of radiator and refill system.

Test for leaks Your done.

Tools needed:

Flat blade screwdriver (to remove hose clamps)

Socket wrench

T-40 torx drive socket

19mm open end wrench (to remove Coolant Temp. Sensor)

Drain Pan (to catch spilling coolant)

50/50 water/coolant (optional, if you are going to change coolant)

Answer 2

If your engine is a 1.9 your thermostat is probably the easiest thermostat in all of car history to change. The water jacket that houses the thermostat is top left at the end of the upper radiator hose. It is held in with 2 torx (star) bolts and it lifts up to reveal the thermostat, which has it's own seal. I believe I paid less than $10 for the thermostat and seal. Now I am wondering how to reset the P0128 error code which prompted me to change the thermostat... any suggestions, anybody.?