Help!!!overheating!!!

[MAP]

Just a little extra on this. My sister's car had an overheating problem where it would only happen at speed. At idle it would cool just fine.

Well the problem was the impeller on the water pump. It was made of plastic and had broken. At idle there was enough coolant circulation to cool the engine but at speed the fluid was just not circulating enough through the system to cool down the engine.

So if you're having that issue, I would check the water pump.

Maybe I'm mistaken but I believe I read somewhere that the 97+ XJs have plastic impellers. Someone here probably knows if this is true or not.

MAP

 

[sacem]

It's possible that the thermostat may not be opening completely and limits the flow which would decrease the heat transfer at the radiator and consequently cause the cherokee to overheat.

One thing that can be done as an experiment is to remove the thermostat completely and let the engine warm up and run it in the situation where it used to overheat.(it will take a long time to warm up) If it doesn't overheat, the thermostat was the problem and it should be replaced with a new one. If the overheating still occurs, you need to look elsewhere and replace the thermostat.

MAP

I have removed the thermostat completly since the first time it begun overheating (about 10 years ago) and never have replaced it, here the lowest temp near home is around 60ºF (15ºC) so the car is never really cold but it will warm up to op temp in about 10 min. I really don't know if that is making me work with a richer mixture for longer periods of time can anyone give a hint on that.

SACEM

 

[muduck18]

yo red96...+ texcomanche..
Quick question...
I had the same problem a few weeks ago, and since have not driven mine much... and about the same time, my A/C died... and this all happened about the same time i added a custom front bumper... flat style bumper, and a hi-lift jack to the front... did you do anything like that to the front of it?

 

[TexasComanche]

The only things that I did before I started having this problem is I added an AC condensor to the front and I had the radiator flushed right after this. I guess I wouldn't understand if the condensor is blocking air to the radiator enough because I hear from GOJEEP that his fans do not even come on at speed and at idle it cools just fine with the fans on. I am going to purge it, check the lower hose, and last and not least - change to a modine.

 

[langer1]

Did you reinstall all the shrouds and guards, those help with air flow.

 

[joe88xj]

i tried replacing my mechanical fan with an electric one and i overheaded on a regular basis, the mechanical fan moves way more air than any electric that will fit in the engine bay on an xj's rad ...lose the electric fan.