Where is the thermostat on a 2002 Jaguar S Type 4.0?

Answer 1

Look on the forward part TOP of the engine. You will find a black plastic housing that has an allen-head hole in a cap that reads tighten to 9 Newtons (can't remember exact torque but I THINK it is 9). That is the thermostat housing. It is a 2-piece housing that has a portion facing downward and a portion facing forward.

The forward portion has 3 VERY small METRIC screws. THIS is where the thermostat is in the housing. you MAY need to remove the air intake as it is a LARGE plastic form-fitted piece that runs directly in front of the housing screws with little clearance. Remove those 3 screws, and inside the triangle-shaped piece is the thermostat.

Look at the ENTIRE piece while you are under the hood. this housing (Both parts) is made of black plastic. It is prone to heat-warping and leaking. An aluminum replacement can be had for a few extra bucks, and is worth the investment.

The housing that is attached to the engine is hard to remove, as the four (4) mounting bolts are small, and VERY hard to get to. It is the housing that has an allen-head recess in the very top that reads like TORQUE TO 9 NEWTONS or something like that.

I replaced this housing in about 2 hours. Longest time spent was determining what size the allen-head bolts were, and getting to them to remove and replace. The area to just replace the thermostat was easier to get to, but to replace the housing with an aluminum one, you will need either an offset allen driver, or as I did, heat a thick screwdriver with a torch and melt a groove above the back 2 mounting bolts in order to get your allen wrench past the housing to be able to get to the back two (2) bolts.

Aluminum housing will be a 2-part piece, just as original, and can be put together prior to installing. (Including having installed thermostat) Then install onto intake, and tighten all four (4) bolts, attach hoses, and check for leaks. Aluminum piece will resist warping longer than the original plastic piece.