Expert: autohelp - 11/26/2009

Question
QUESTION: I have a 1998 Cadillac Deville with the 4.6 V8 Northstar engine. The problem I am having is that the engine appears to be running hot. The temperature gauge reads around 230 degrees, but when I check the antifreeze reservoir the water in it is cold. The radiator hoses are hot, but the water in the reservoir is cold. I changed the thermostat, but that did not work. Could the problem be the coolant temperature sensor? if so where is it located on this engine.

ANSWER: I have been out of town, Do you still need help ?.

---------- FOLLOW-UP ----------

QUESTION: Yes, I still need the help. I found a replacement sensor but do not want to buy it until I know that is where the problem is. One thing I forgot to say is that the last time the car went out it shut down due to the over heating problem the temp was around 290 that time.  I did not check the coolant reservoir then, but I'm sure it was cold.

Answer
Unfortunately this engine has a very common problem of stripped threads in the engine block which allows the head bolts to loosen which allows combustion chamber pressure into the coolant passages thus restricting coolant flow.

Check the torque on all the head bolts.