I'm looking at buying a 98 grand cherokee but the owner says she's getting rid of it because when it's hot outside (90+) the jeep will only run for a short time and then it shuts itself off and you have to wait for it to cool. It doesn't have this problem when it's cooler outside. Any idea if this is a cheap fix? or what the problem is?

 

I know you changed your water pump from stock to stock (probably). Hesco makes water pumps that provide 10 to 20% more cooling efficiency that stock.

 

I know you said you changed yours but a Hesco waterpump will provide 10 to 20% more cooling efficiency vs stock.

 

Velcro -
Sounds like it's fooling you - the gauge shows hot, but it's not.
overheating will not affect the blinkers or anything else. It's electrical causing the gauge to lie.
Do the lights flicker or dim?

Start with a good inspection - look for loose wires, insulation worn etc. -underhood and under dash.
Find the ground strap from the body to the battery - gauges etc are grounded to the body but if that connection is bad - all kinds of weird things happen.

Then I'd unplug the alternator and drive it. If it no longer fluctuates you unplugged the problem - alternator.

No? Reconnect it - pull out all the non essential fuses then see if it does it. If it stops fluctuating, one at a time replace the fuses until it does it again - bingo - you found the circuit.

You have to be a detective!

 

Also clean the Engine harness plug in at the firewall, they sometimes will corode causeing electrical issue's.

 

in addition to cleanign the connectors put dialectric compound on them this stuff works very well . i use it on everything its a conductive goo/grease usually clear

 

Thanks so much guys! sorry it took so long to get back but i didn't figure it out until Friday.

I finally spotted a grounding strap that had rusted in half! it was the one that connected the engine block and the body. Put a new one in and not it works great!

So glad i don't have to sell it now!

Thanks again for all the help

 

im having the same problem on my cherokee its been getting hot the aux fan wouldent come on and even in the winter if i drive it around and have to sit in traffic the temp it will climb.

i still have a plastic coolant bottle ive replaced it 3 times checked the aux fan relay fan kicked replaced the coolant sensor nothing still fan did not come on thing still gets hot.

i replaced the t-stat nothin checked the plastic bottle added a screw clamp to it nothing there.

Checked the waterpump it appears to be pumping good replaced the antifreeze still it seems like it will over heat.

Ill have to put it in neutral at a stop light and run the heat to keep it down when it starts climbing

 

What is it? Did you change the right sensor?

Overheat is the first sign of head gasket, couple easy checks;

Full, cap off power-break it a second. If it blasts or blows out, gasket.
Or if a smog sniffer senses Hydrocarbon at the cap.................gasket.

Just an easy start ^. My fan sensor is on the radiator.