Hey everyone, After an overheating experience I replaced the water pump (bearing turned out to be shot), thermostat/thermo housing, and hoses. The car fired right up once everything was installed and I began the process of adding coolant/bleeding the system.

I have a portable gauge reader that tells me the real time coolant temp. so while I was doing this process I could monitor the exact reading. After a few attempts to get the air out of the system I finally got the temp to start dropping. Strange thing is it went from 190 deg. (about 17 deg cooler than normal operating temp) down to about 180 - 182 then just sat at that temp. I figured the cooling system was doing its job so I capped it and then got ready for a test drive down the block.

After about 3 min of driving I see the temp start climbing on my reader from 190 - 200 - 205 - 211 (at this point I am almost back home as it is not looking like it's cooling the engine properly) - 220 - 228, then as I am pulling up the driveway the temp starts dropping.... 210 - 205 - 190.

My temp gauge on the instrument cluster never left the center position as it didn't get hot enough but this can't be normal right? Could this just be the coolant cycling through the barren system as practically all the cooling components were replaced besides the radiator. If my head gasket was blown It would have gotten to overheating range right? and not just dropped back down to below operating temp? Praying that this is not pointing to head gasket. There was no coolant on my oil dipstick after the overheating situation when I checked dip stick but I did notice some white substance (coolant/oil? in the thermo hosing and one of the hoses) before I replaced the components.

Any input greatly appreciated. I am going to let it cool down then leave the cap off and see if this might have been due to some air still trapped in the system

*UPDATE*
I may have overreacted a bit there, I think it was just some air trapped in system. Although the car is running much cooler now, perhaps that "normal operating temperature" I mentioned which was at around 207 is now around 195. Anyone else have a temp monitoring gauge that can let me know what your normal operating temp is? I think these new components are just allowing my car to run cooler than before and 207 was not very normal after all, would be cool to hear what others cars temps are running at. The fluctuating temp seems to have gone away, took about 10 laps up and down my street and temp stayed between 190 - 198 but haven't gone on a high speed test yet.

 

Did you shut your car off after overheating and would it not crank back up. Did you have to replace pump first. My 2011 xj over heated from pump going bad and i shut it off on the hwy once i got to a safe spot. Will it start back up once pump is changed

 

Hey Mario,

My car actually shut down automatically as it took me a little while to get to a safe spot to pull over. You should have the entire cooling system checked before you toss a water pump at it. Are you sure it was the water pump that went out on you? If it is the water pump then yes, replacing it would allow the car to start back up and should be good to go. Could be something as simple as thermostat though, a 2011 should not have a water pump go out but I'm sure its possible. Mine is a 2004.