I just recently replaced the thermostat, thermostat housing, temp sensor, serp. belt, water pump, radiator, rad cap, and coolant outflow and inflow hoses. I removed the old Mopar temp sensor and replaced it with a Delphi, and replaced the old Mopar single channel rad with a CSF twin channel. While the cooling system seems to be doing its job, i.e. the engine is running at about 200-205 when I've got some air moving past the car, the temp is not stable. My XJ used to run at a stable 210 when I had my old parts, and now its within, or below, limits, but it bounces all over the place depending on driving conditions.

Is this a symptom of something or it this a typical occurance? Have other people experienced this? It the new temp sensor just more sensitive?

 

Bounces all over the place? Or rises up a bit, stat opens, goes down a bit?

 

My temp bounces from about 160-205. I was going to ask about it too.

 

Must be an epidemic. Mine started doing that, too before and after replacing the thermostat.

A little later I replaced a 2-year old fan clutch with no real change.

 

Sounds like a bad thermostat. IME the cheap ones aren't very reliable. I've tested a few different brands and temp rating thermos by sticking them in a pot on the stove, ironically the 180* opened after a stant 195*. A murray 195* thermo didn't open until the water reached boiling point. I'm amazed no one has designed an electric thermostat to replace these unreliable wax based thermos.

 

Most likely cause would be the thermostat. Some people say to use OEM only.

 

83501426 Mopar stat. It's all I'll use anymore.

 

My fail safe one from autozone works well. Replace the thermostat as everyone else stated.

 

200-205 is not stable???????.... .....seems like it to me.