Overheating issues

Mcnenc1

Mcnenc1

TJ Enthusiast
Joined
Feb 11, 2019
Messages
122
Location
Tampa
Help my 2004 Jeep TJ 4.0l.

No leaks from pump. Hoses are warm/hot to touch when running. Fan is in good condition and operates as it should.

Replaced —> thermostat, coolant (flush and cleanse)

Problem was resolved for 2 months. Took it on the highway (65mph) and overheats. Just around town it won’t overheat.

I’m having a water pump come in the mail soon and will update ASAP when replaced but until then is there any o
 
Change the fan clutch at the same time as the water pump, unless you can otherwise verify the clutch engages at high temperatures.

Did you use a descaler when you flushed the coolant? If the radiator is plugged you would get some significant overheating.

I'd suggest that and then replace the radiator next.

Does the heat work well? If the heater core gets clogged the radiator is more than likely clogged as well.

Just be warned the chemical flush might reveal other problems. It may unplug an old leak in the radiator or even reopen a clog in a blown gasket. But at least you find out about those problems when you can expect them versus on the freeway far from home.

You probably already know about this trick, but if you're driving and start to overheat, roll down the windows and blast the heat at the hottest setting and highest fan speed. It's often enough to keep you moving. Basically you're using the heater core as a second radiator. Doesn't solve the root problem, but it can be useful if you overheat and have to keep driving
 
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Okay I’ll replace the radiator as well. As for the Descaler, no I didn’t use that...

The heater actually went out a while back. I live in south FL and never use it.. I did see it was the actuator that’s bad just never replaced it. Could it be that???
 
Be sure to be BACKflushing the system. This will help push debris and scale out of the system. If you flush the fluid in the same flow direction you can be just lodging crap deeper into the radiator and core.
 
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When it only overheats on the highway it's not the fan. The fan is for low-speed operation like offroading, slow or stop & go driving or when its idling. What radiator is installed? Mopar? Store brand? A Chinese radiator from an online website? Could it be clogged with lime/hard water deposits from having used tap water instead of distilled water to mix with the coolant?

Has your Jeep ever been in a muddy area where its cooling fins might be clogged with mud?
 
No it’s an OEM part. Never been in the mud. It doesn’t leak and it was back flushed and cleaned with dissolvent because I thought it was clogged. We did this twice. And refilled it with fresh new coolant. This last for maybe 2 months and the over jarring issue came again
 
Jerry Bransford said:
When it only overheats on the highway it's not the fan. The fan is for low-speed operation like offroading, slow or stop & go driving or when its idling. What radiator is installed? Mopar? Store brand? A Chinese radiator from an online website? Could it be clogged with lime/hard water deposits from having used tap water instead of distilled water to mix with the coolant?

Has your Jeep ever been in a muddy area where its cooling fins might be clogged with mud?
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Also, I noticed my hot air isn’t working. Upon further investigation my air actuator is not working? Could this in turn cause over heating in the engine?
 
Before you replace the radiator, take the cap off (when the engine is cold) and look at the ends of the cooling tubes in the top header. Are they unobstructed?
 
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Daryl said:
Before you replace the radiator, take the cap off (when the engine is cold) and look at the ends of the cooling tubes in the top header. Are they unobstructed?
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The right tube is broken underneath. Looks damaged/rotten

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Okay, let’s get back to looking inside the radiator. When the engine is cold, remove the cap from the radiator and look into that hole. You should see a few of the cooling tubes. Are they clear of debris buildup? Take a picture and post it if you’re not sure of what I’m asking for.
 
Looks like some blockage of the cooling tube passages. Take a toothpick and try to remove a small sample and wipe it on a paper towel. What does it look like?
 
See if you can find a local radiator shop. Take it to them to be cleaned and inspected. I just did this to mine and it was a $20 bill. If you plan on flushing your system, do it now before you take the radiator into the shop.
 
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