Got a '91 Dodge Daytona Shelby (4-cyl 2.5L Turbo, Manual). Ok, I have a strange problem. When I cold-start my car and it warms up, the temp gauge goes almost all the way to H when I drive, and then suddenly as if the computer wakes up, the temp gauge drops all the way down to just above C, then comes up to center position and stays there indefinitely. If the car is still warm when re-started, this problem doesn't happen. But if the engine cooled down all the way and I have to do a cold-start, same thing. It has to go almost to H before the magic moment happens and the needle comes down, then up to center and stays where it should.

A couple observations. If the car warms up just by idle (without driving), it doesn't do this until the driving begins. During driving, low RPMs make the needle go hotter faster and higher RPMs make the needle stop in its tracks or even cool down a bit. Generally, I have to really open her up (rev to high RPMs while I drive) in order to wake up this system and make the needle "snap out of it". When I get on the freeway, this problem fixes itself fast. When I have to drive slowly in traffic, it's a nightmare and the needle would almost go to H. It's nerve-racking.

It used to not do this until recently when the deep freeze set in here in Jersey. Anyone know what this problem could be? Anyone had this problem? I really could use some help on this. HELP PLEASE!!

Thanks

 

It sounds like you may have an air pocket in the cooling system. If there is an air pocket it will settle at the highest point which is in the thermostat housing. The temperature sensor is also in the thermostat housing on the side of it. I think that the air pocket/bubble is keeping the coolant off of the thermostat causing the high temperature and the movement of driving splashes it onto it enough to get it to open and cycle the coolant, but when it cools off completely the air pocket comes back. To get rid of it you need to remove the recessed bolt on top the thermostat housing and top off the coolant in the radiator until it comes out of the hole. Then put the bolt back in, use thread tape on the threads of the bolt to make sure it doesn't leak. Also make sure that the overflow jug/bottle is filled to the appropriate mark on the side of it. This should solve your problem, if not, let me know.[sm=smiley2.gif]