overheating

changingtime · **Posted:** Mon May 30, 2011 9:52 pm

i was towing back from a trip through rolling hills and the jeep started to overheat...got all the way to almost the red. while flat driving it sat at half way...but anytime speeding up working the engine, temp would jump up quickly...

fan running, original t stat...thoughts?

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

You are not overheating and can just keep running it. The engine self regulates the coolant temp to not exceed 239 F at the t-stat. This is accomplished through an active derate in the allowable fueling, the AC will automatically shut-off and when things get to the extreme the warning chime will start going off. At that point, we turn the heater on max to tranfer more heat away from the coolant.

changingtime · **Posted:** Mon May 30, 2011 11:05 pm

thanks keith, i just read the information on your site...starting to wonder if i had the tsb done...

DOC4444 · **Posted:** Tue May 31, 2011 10:40 pm

Are you talking about the engine driven fan or the electric AC fan? I have a similar problem when towing. Even after replacing the OEM fan clutch, the clutch does not engage and the temp gauge pegs quickly going uphill (even after cluster recalibration). I bought a Hayden extreme duty clutch that is supposed to lock between170-190 degrees.

Will report on install.

DOC

NJ KJ · **Posted:** Thu Jun 02, 2011 9:42 am

I'm having this problem too... i have 105k on the clock and have never had a problem with it before... now the temp gauge is all over the map... even when i'm not towing... i'm not sure why its running so hot all of a sudden... i was think of replacing the t-stat and the radiator... not sure which to do first.... or if this will even fix my problem...

DOC4444 · **Posted:** Thu Jun 02, 2011 9:59 am

If you can get hold of a VAGCOM, you can read what the sensor is sending to the ECU in real time. Could be a sensor or gauge problem. Erratic needle movement is probably not overheating, but you can check that with a probe type external thermometer.

DOC

eleonard3012 · **Posted:** Thu Jun 02, 2011 12:40 pm

I have the overheating problem a well. I have been struggling with it ever since the vehicle was new, and according to the dealer it doesn't exist under warranty, but now if I want to bring it in they can charge me a $90 diagnostic fee.

Anyway, it happens when I am not towing but climbing >6% grades in the warm New Mexico Summer, high 80s to low 100s. It happens at highway speeds ~80 mph or at mountain road speeds 20-50 mph with the ac on really makes the temp climb I usually use windows on mountain roads and try hold out for highways. It has no problem at off road speeds. I usually turn on the heater when is passes 3/4 and let it cool off but I don't like that. The stock system should be able to dissipate the heat of hot days here. I have had the TSB done with the gauge recalibration, and installed a Hayden ultra-cool fan after a trip in a blizzard iced up the stock electric fan and caused the motor to burn out. I added also a tranny cooler but of course it didn't help the engine cooling. I just finished replacing the t-stat but it was stuck open so shouldn't effect the cooling. The mechanical fan works in my latest test last year but should add too much at 80 mph. I had the coolant flushed at last year at 5 years only 85k on the clock. After extensive research i have found some options but I don't know which one is best.
1. Change to a Hayden heavy duty viscus fan clutch
2. Use an 06 viscus fan clutch
3. Add a fuel return line cooler
4. new radiator, mine might have significant fowling. If there is a way to check this I would be appreciative.
5. reprogram the timing
6. Add and oil cooler
and anything else someone would recommend. I want to keep the cost down as I am a poor graduate student, but if I have to drop the Benjamins I will.

Wobbly · **Posted:** Thu Jun 02, 2011 2:46 pm

You might want to verify that your temperature gauge reading is fairly accurate. Pull over when your gauge is reading around 3/4 and shoot the radiator hose and thermostat housing with a laser thermometer. Available for $30 at Harbor Freight.

papaindigo · **Posted:** Thu Jun 02, 2011 4:41 pm

X2 on Wobbly's comment, before doing anything based on the temp gauge reading I'd check to see if the gauge is remotely right. If not a replacement sending unit for the tstat housing should be cheap and I've certainly seen sending units go bad. As to your proposed options: if your engine driven mechanical fan is kicking in at the appropriate point then I don't see 1 and 2 doing much unless they make it kick in earlier; 3 don't see why this would help for several reasons; 4 check out viewtopic.php?f=5&t=58582&p=651480&hilit=radiator+plugged#p651480, any radiator shop can check/others may have advice on DIY; 5 if it's right you shouldn't overheat; and 6 might help (sorry was thinking tranny cooler) but then given other comments on how hard it is to overheat I'd advise finding the cause.

Other options 1) sometimes a bad radiator cap (on the CRD it's the one on the plastic tank on the firewall) can cause overheating; 2) I don't offhand know a good test on the CRD (I have vague memory of on a cool engine take the radiator cap off and look for circulation) but a bad or partially bad water pump can cause overheating; 4) have you checked the various water hoses to see if one is partially collapsed and blocking circulation; 5) for a better fan without the clutch see viewtopic.php?f=5&t=51618&hilit=flex

eleonard3012 · **Posted:** Thu Jun 02, 2011 5:35 pm

Thank you papaindigo. To clarify, I suggested the the fuel cooler on the simple premise that rejecting any heat going into the engine would help cool it. I know its intended purpose is not for engine cooling. Just some brainstorming.

The water pump is not totally bad as I do have circulation and the condition has not changed since the vehicle was new. I could check if someone knew the flow rate out of the water pump I could check that fairly easily. This also leads me to be skeptical of a clogged radiator but it doesn't hurt to get it checked. I could simply replace the radiator cap, I don't think it is that expensive. All of my hoses are fine I inspected all of them when I did the t-stat. I don't think I want to go without a fan clutch as I often find myself in sub-zero temperatures on ski trips to the northern part of the state. We have a crazy climate here. I will definitely check the temp of the t-stat housing, at 3/4 it is supposed to be around 200 F correct?

Wobbly · **Posted:** Thu Jun 02, 2011 7:55 pm

3/4 reading on the temp gauge is approximately 230 degrees F.

EDIT: With the Eco-Tune.

ATXKJ · **Posted:** Thu Jun 02, 2011 8:54 pm

Well - the only overheating I had was climbing Colorado mountain passes
100+ in traffic jams in Texas with the AC on - never had an effect

and even the 'overheat' was the gauge on the right side - no alarms or power loss
however based on the other folks experience - I suspect 05's tend to have the marginal fan clutch and I've never heard mine turn on.
so before I go back to Colorado - I'm planning on RetMil's upgrade - which is
eleonard3012's #1 the Hayden heavy duty clutch + an 02 tow package fan (should be 11 bladed plastic with the same bolt pattern)

and maybe a fuel return line cooler - although the alternative to that is - don't get below 1/2 tank - and the heat will dissipate.

and FYI - you already have a oil cooler - oil/water under the Turbo

changingtime · **Posted:** Thu Jun 02, 2011 10:31 pm

I went to the dealer and got the gauge module updated under the TSB. according to keith over at gde, it's not overheating and just go buy what the vehicle does...sounds like when the air starts cutting off, then you may have an issue. but the engine is self protecting, so fuel starts getting caught off as well...

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

A picture detailing the coolant gauge temp profile with original release from Chrysler:

And one showing the temp profile after the cluster update:

dieseldoesit · **Posted:** Fri Jun 03, 2011 1:01 pm

Just a thought, but has anyone that has had the overheating problem washed out their radiator, intercooler, and condenser?

I had an old chevy that would over heat. I turned the hose on the radiator to wash out the fins and all the gunk that was in there, problem went away after that.

Might not solve the problem, but maybe you can talk the wife into helping you with it and get a quick wet t-shirt contest in while working on the jeep. :SOMBRERO:

JL Rockies · **Posted:** Fri Jun 03, 2011 1:29 pm

There are many threads about this issue. I've replaced everything, flushed everything and had a dealer look at it. If I don't lock out OD, and turn the heat on when climbing grades, the needle will blaze past the red zone, cut the AC and cut power. My solution was to buy a 4Runner but the KJ is still an excellent winter vehicle since it's not a problem to run with the heat on. Anything warmer than 60 deg eliminates the KJ from Rocky Mntn road trips.

tonycrd · **Posted:** Fri Jun 03, 2011 1:53 pm

Ever thought about installing an extra tranny cooler?

JL Rockies · **Posted:** Fri Jun 03, 2011 2:30 pm

Yes, but Doc tried it prior to LJS 2009 since he was having the same issues I was. It made no impact on his so I figured why bother? I was really hopeful after changing everything with my timing belt but after an April trip to Comb Wash, my hopes were dashed and I gave up loosing sleep over the KJ. The Toyota works well and clears 33" tires without a lot of mish-mosh so I've got that going for me.

eleonard3012 · **Posted:** Fri Jun 03, 2011 2:44 pm

Quote:

and maybe a fuel return line cooler - although the alternative to that is - don't get below 1/2 tank - and the heat will dissipate.

I am a poor college student my tank is always below 1/2 tank. :wink:

It only happens in high torque situations, so running in Texas 100+ would be alright as long as you are not going up long hills.

Quote:

Ever thought about installing an extra tranny cooler?

many people already have done this, including me. They run the tranny cooler on the bottom half of the condenser. This doesn't affect engine cooling.

Quote:

Just a thought, but has anyone that has had the overheating problem washed out their radiator, intercooler, and condenser?

On a regular basis

changingtime wrote:

I went to the dealer and got the gauge module updated under the TSB. according to keith over at gde, it's not overheating and just go buy what the vehicle does...sounds like when the air starts cutting off, then you may have an issue. but the engine is self protecting, so fuel starts getting caught off as well...

I know the engine self protects, but I would rather turn on the heater and keep going then have a bunch of chimes and my fuel cut, often there are few places to pull of on the roads that this happens on. And if this happens with just me and my bike on the roof, it means that I cannot tow. I want the option which is why I have the tow package. I need to increase the heat rejection of the engine so I can drive up mountain passes in the summer without glancing down at the temp gauge every minute. Upgrading the cooling is a lot cheaper than getting a 4-runner.

Also sorry of the thread jack

Wobbly · **Posted:** Fri Jun 03, 2011 3:39 pm

Any possibility that these overheating CRDs have their viscous heaters permanently engaged as Roostre feared that his was?

"When I put the clutch face back on it did not have the clearance necessary to disengage!! This liberty may have been running for its entire life with the VH engaged! I added a washer to make sure it couldn't drag for this temporary (I hope) installation. "
Roostre

overheating

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