Overheating is one of the most dangerous and common issues with our Jeep’s engines.
If your Jeep overheats, you should diagnose and find the reason as soon as possible, replacing/rebuilding the engine is an expensive fix and it woulds be better to avoid it.
How to avoid overheating?
The first thing would be to keep the cooling system in proper shape.
1. Check the coolant level – Is it in the correct range? if it is not, add coolant and find out why it is missing.
2. Verify that the coolant is clean with no oil/dirt/rust in it. **
3. Check for leaks. have a look under the car, look at the hoses and their connections to the radiator/thermostat/engine.
4. DO NOT use regular water as coolant.
5. Check the coolant hoses, replace them if they are dry/cracked.
** Oil in the coolant points to a bad cylinders head gasket (or, in the worse case, a crack in the head/engine block themselves), as you can understand, that is much more expensive fix and you Jeep will probably suffer from overheating.
My Jeep overheats, What should I do?
First, you should identify when does it overheat, is it under load? is it while driving on the highway? or maybe while standing in traffic?
If it overheats in traffic/standing, but doesn’t on the highway:
Check the fan clutch (if any) / the electric fan. Usually, there are useless on the highway since there is already cold air flow through the radiator.
Checking the fan clutch is a little tricky, but a good indication is asking a friend to turn the engine off (when it is hot) while you look at the fan. if the fan continues to spin after the engine is off, consider replacing the fan clutch.
DO NOT TRY TO STOP IT WITH YOUR HANDS (or any other body part/tool)
Check the radiator and the coolant pump (coolant pump checking requires some work, so it is not the first thing to do… and usually it will start leaking before ending its life).
If there is a play in the coolant pump pulley, or there is coolant around it, replace it.
If it overheats all of the time (not related to driving conditions):
Check the thermostat, maybe it is stuck and can not get to a fully open state (in most cases, it is a cheap part and unless you replaced it during the last year or two, if you already took it out for checking, just install a new one instead)
Next, check the radiator, it might be clogged and dirty. Have you ever cleaned it? what is the color of the coolant? is it clean? how old is the radiator? do you see rust in it?
Most of the overheating issues are being solved while cleaning the radiator or replacing it with a new one.
As written before, check the coolant pump.
Check the radiator cap – a radiator cap that won’t hold pressure might cause overheating problems.
If you replaced any of the cooling system components (besides the fan/fan clutch) you should bleed the air out of the system.
In the Cherokee XJ you should fill the radiator with coolant and let the engine work and reach normal working temperature for at least 5-10 minutes. then, install the radiator cap in place, turn off the engine and fill the coolant bottle to the max.
In the Grand Cherokee WJ there is a screw that should be open, we will publish an article soon.