Jeep is over heating

[JeepWJ19]

My jeep is now my weekend vehicle. After going to pick up my car monday, it was rather hot and of course going through slow traffic.

I get to the garage and my jeep was sitting a hair above the 212ºF mark. I quickly turned the heat on the whole way and turned the fan on high. I figured it would get the coolant moving? I hurry up and get my car started and drive it out of the jeep's parking spot (I store my jeep at my family's garage because there are too many cars at home so I swap cars on the weekend). When I got back in the jeep it was 235ºF. I quickly but gently on the gas put my jeep in the parking spot and quickly shut it off.

This is the 4.0 and not the 4.7 so not worried about dropping a valve seat but is there anything that I should be worried about from it reaching 235 degrees?

I don't know when the last time (if ever) the thermostat was changed so I'm hoping that's all it needs and will be the one I start with. Having done a thermostat replacement before on my dad's 4.0, it was easy. But the belt being in front of a bolt on the housing made it somewhat more difficult. Is it possible to loosen the belt just a smidge just enough to lift the belt a little and then re-tighten it? Is that process even worth it?

Secondly, I did not recall if I heard my fan going or not. I was too focused on getting that thing parked. Really hoping the fan relay and/or the fan motor are sound. Going to focus on one thing first, will get the multimeter out if necessary. If it's just the relay, fine. If it's the motor, I'm giving it honest thought of adding a GM 11 blade plastic mechanical fan and running the electric fan as a combo. Both can fit and it's already lifted etc. so I'm not worried about losing .1 mpg because of a mechanical fan.

 

[ruhroh]

Have a 99 WJ. Overheated many years ago. Was the cooling fans' brush motor.

 

[JustN89]

Shouldn't have done too much harm. Those 4.0s can take a lot of abuse. That doesn't sound like a thermostat issue, but it wouldn't hurt to replace it. It's not overly difficult to do. Normally, when it's having difficulty cooling at idle, my first thought is the fan with the water pump and the radiator being next.

 

[Nick1994]

I battled a lot last year with my Jeep and running hot.

If you haven't revamped the cooling system in a while, now is the time. New thermostat, radiator cap, flush the coolant a few times, check the water pump to see if the blades are worn down, and replace the fan clutch.

The 4.0L needs a lot of air flow, and your Jeep has a mechanical fan clutch. Napa sells good ones, they're pretty cheap too.

Does your Jeep have an electric fan and a mechanical fan?

 

[demarpaint]

I think you'll be fine. The 3.6L in the Wrangler JK and JKU cooling fan doesn't kick on until 232F. Granted it isn't the same engine, but I doubt you did any damage.

 

[JeepWJ19]

Originally Posted By: JustN89
Shouldn't have done too much harm. Those 4.0s can take a lot of abuse. That doesn't sound like a thermostat issue, but it wouldn't hurt to replace it. It's not overly difficult to do. Normally, when it's having difficulty cooling at idle, my first thought is the fan with the water pump and the radiator being next.


Thanks didn't even think of that!

 

[JeepWJ19]

Originally Posted By: Nick1994
I battled a lot last year with my Jeep and running hot.

If you haven't revamped the cooling system in a while, now is the time. New thermostat, radiator cap, flush the coolant a few times, check the water pump to see if the blades are worn down, and replace the fan clutch.

The 4.0L needs a lot of air flow, and your Jeep has a mechanical fan clutch. Napa sells good ones, they're pretty cheap too.

Does your Jeep have an electric fan and a mechanical fan?


My Jeep has a 16" electrical fan. There have been many WJ owners switching to or running the electric fan + mechanical fan combo because these WJs have had fan relay and fan motor issues. What has been documented is the GM 19" 11 blade plastic fan with Hayden heavy duty clutch works in these Jeep's. There's enough room for the combo to be in there and apparently that 11 blade fan can really move some air.

 

[Chris142]

See if you are getting 12v to the fan when it's 230f. If it's not.There is a fan relay under the pass side head light. Remove the light and cut an access hole in the plastic bumper cover. Or spend all day removing the entire cover.

No need to remove the belt to get to the lower thermostat housing bolt. There is just enough room to get a socket on it. But if the stat was stuck the fan would be on.prolly not the stat.

 

[dlundblad]

Most likely the fan relay under the passenger headlight if the fan wasn’t on. Easy fix but the headlight panel will need trimmed unless you want to remove the hole thing. Pop the headlight out and cut a 5x5 hole on the flat right below it.

I upgraded to a mechanical fan too. Mopar fan and AZ clutch.

 

[dlundblad]

What Chris said. Lol

 

[bullwinkle]

An easy way to test the electric fan & relay is run your A/C and see if it comes on. Also, if your fan clutch is good, it should engage at a cold start and disengage after 15-20 seconds-it's possible neither is working.

 

[David2431]

Been there and done that with a 2001 WJ six. Had the temp red lined for a short bit. Problem was the electric fan.

Did it before that and problem was the relay. Previous post is AOK on turning on the A/C to see if the fan will engage.

When it's fixed do an oil change and get on with life. No worries if you didn't run it much while hot.

 

[JeepWJ19]

The is already a hole under the light. Must have been previously done, I noticed it when I replaced my headlight some years ago.

Thanks for all the info! Will be waiting until this weekend to do anything.

 

[Nick1994]

Rock Auto lists a mechanical fan clutch for this Jeep. Did someone take it out and swap in an electric?

 

[Chris142]

Originally Posted By: Nick1994
Rock Auto lists a mechanical fan clutch for this Jeep. Did someone take it out and swap in an electric?
the standard one gets only the electric. Towing package gets both.

 

[jeepman3071]

Originally Posted By: Chris142
Originally Posted By: Nick1994
Rock Auto lists a mechanical fan clutch for this Jeep. Did someone take it out and swap in an electric?
the standard one gets only the electric. Towing package gets both.


Yep. The water pump pulley should already have the threads for it. If it were mine, I would just add the mechanical fan and fix the electric one. A radiator flush, new water pump and Stant Superstat 195* thermostat and you should be good to go.

 

[dlundblad]

If you do add a fan, entertain the GM 11 blade found on S10's, Blazers, Astro vans etc. I tried one, but couldn't get it to fit. Turns out I needed to go through the bottom, but couldn't because I had the skid plate installed.. that makes it a bit of a pain. My Mopar fan with the offset blades goes in and out through the top. I believe you need the Hummer H3/ Chevy Colorado fan clutch for the 11 blade.

Double check the fan first. Towards the end of my original e fan's life, I replaced the relay one last time thinking that was the issue. Turned out to be the motor. Everything is good now.

 

[artificialist]

I'm not completely familiar with Jeep cooling systems, so this might not apply to you. Some electric engine cooling fans have resistors for variable speeds. One could fail and cause the engine fan to only work in certain situations, or not work at all.