Help!
Car was running fine but the cooling fans were running for quite a long time upon shutdown. After reading on here, I ordered a new replacement temperature sensor. When I received it I set about to replace it (the new one, externally appeared identical to the original one) When I put a wrench on the original sensor, it came loose but was not made to be replaced (no threads, knurled but nonetheless it had a hex configuration). So in my infinite wisdom, I decided to attempt to screw in the new sensor and it went in. So I figured it was a correct replacement. However, when I started the car, it ran very rough and extremely rich. I don't know why. Also the temp gauge remained on cold even after running it down the road a couple of miles, the engine smoothed out but the temp gauge remained on cold. This morning I started it again and it did the same thing, very rich and rough idle. Later this morning my wife tried to start the car and it cranked but would not start. I left it till today when I called Jag and got the correct sensor which includes the plastic pipe which connects to each head. I replaced all with the new unit and it cranks over but will not start. I also replaced the plugs rthinking that they may have fouled due to the rich condition. It did not help. I am at a loss as to what may have happened to cause this problem and would appreciate any help.

 

FWIW;
The problem was cylinder wash down. Evidently the rich running condition washed down the cylinders. A little oil and poof, all set.