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2011 grand Cherokee overheating

4K views 3 replies 4 participants last post by  Jeeple1 
#1 ·
Hey guys, im totally stumped on this one. Started noticing my grand Cherokee over heating when I get the RPMs up around 3000 to 4000 and when I climb a hill. Looked over engine and no leakes, oil isnt colored and no other signs. Start with trouble shooting parts. Replaced cap, then water pump, then radiator, then radiator fan. Did thermostat a while back but dont think it would be bad after about 10K miles. Im stumped to what it could be? When driving and when it starts to overheat ill get off the gass and crank the heat on high. The temps come down to normal but will rise again when I climb or rev back up. Any help is appreciated. Thanks all in advance.
 
#2 · (Edited)
Are you towing a heavy load when you encounter this overheating? Assuming in the past you've done the exact same thing, without overheating?

Have you confirmed the Fan is actually turning on? A brand new fan with the same old failed relays or PWM module would not fix the problem. The Standard Fan is high and low speed, with the low speed being modulated by a thermister in the fan shroud. When high speed is needed, a relay trips to power the other element in the fan motor to increase torque and speed. If you have the HD Fan with the TOW Package, it would control speed with PWM, I believe directly from a square wave generated from TIPM or PCM, there is a module, a solid state relay, really a big transistor pack to amplify the square wave up to the power levels needed to run the fan.

Was there any deposits or scaling on the parts you removed?

Have you flushed the system thoroughly and filled it with 50/50 mix of HOAT and distilled water?

Have you checked for any trouble codes stored?

Most of the Anti-Freeze Market has been hocking OAT as some sort of Universal Anti-Freeze, its the farthest thing from it. So its easy to have had incompatible anti-freeze mixed with the HOAT, it starts to form deposits and could be coating or clogging the Cooling system..
 
#3 ·
Hey Tom, I know this post is old but did you ever figure out what was causing your Jeep to overheat? I’ve have the same problem. Drives completely fine until I go up a grade & rpm’s are between 3k-4k.

If you see this & have a minute maybe you have solved the mystery haha
 
#4 ·
When you replaced the thermostat, did you use a Mopar thermostat or an aftermarket one?
I and a lot of others have had this issue with aftermarket thermostats, they work for a while then slowly fail to open all the way, reducing flow and causing overheating at higher RPMs due to the bottleneck. When the RPMs go back down the bottleneck is reduced and the temperature goes back down.

Replace the thermostat with an Mopar one (Rock Auto carries them), they are expensive compared to the aftermarket ones (for apparently a good reason), but should solve the issue.
 
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