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ob1jeeper

Cooling off Ladybugs TJL…

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While climbing the 87 up to Payson, to attend the recent Rim trip, Ladybug's TJL experienced an occurrence where the temp gauge was slowly climbing, then suddenly went nearly full scale into the red, with the check engine lamp illuminating approximately 1/2 mile from the top of the grade.

 

Since there was no loss of coolant into the overflow audible, nor the smell of a cooling system burping hot coolant into the overflow or onto the ground, we continued, albeit at a reduced throttle opening to the top of the grade, where within a 1/2-3/4 of a mile the temps dropped back to a more acceptable range.

 

While sitting around the campfire chatting, the topic of overheating was mentioned by a few others, with similar experiences being shared. Since the experiences were VERY similar, I got to looking at those vehicles which had this issue, and noted that ALL of them shared three things, which stood out to me as possibly being at least contributors to this cooling issue.

 

Those similarities were:

A- a lift of at least 3" (meaning higher wind resistance at highway speeds, which equates to the engine needing to work harder, that it would in OEM configuration on the same grade or conditions…)

 

B- tire size of at least 33" (again, larger tires mean BOTH a change in gearing which we all think of and know immediately, but also a change in the inertia, due to the tires acting as flywheels. The larger the tires, the more inertia that is need to be overcome, which again works the engine harder for the identical conditions than it would have as an OEM stock configuration vehicle)

 

C- winches mounted in front of the radiator, in such a manor that they were blocking what could be a significant level of airflow.

 

With those thoughts in mind, upon returning home, I began the quest to discover and repair whatever was going on with Ladybugs TJL. I began this quest by first calibrating, then installing a thermocouple into the top tank of the radiator. The reasons for using a calibrated gauge was to;

A- verify whether the temperatures which the stock gauge was showing were reasonably accurate

B- to quantify and verify whether there was a cooling issue at all, and not just a calibration issue.

 

The first "test/evaluation run", showed the gauge to be reasonably accurate, with temps climbing unacceptably high before even getting to my intended test grade (Yarnell hill).

 

Due to the slow climb of the temps, it was apparent that I either had an airflow or a coolant flow issue to resolve.

 

In order to understand what role the winch played in this cooling deficiency, I removed the winch and mounting bracket, and made test/eval run #2, with results being similar, but taking a longer period of time and miles, as well as gradient of the road surface, to obtain temps that were unacceptable. That said… It was STILL reaching unacceptable temps. :(

 

That meant that airflow changes due to the winch alone was not enough of a change to cause acceptable cooling performance. Since I started looking for airflow deficiencies, I performed a visual and tactile inspection of the fan clutch. It was tight (NO wobble or looseness), no leaks of the viscous fluid noted, and manually "felt" as if it had sufficient resistance to reach max RPMs. IE: I saw nothing that stood out to me as having anything wrong with it.

 

This led me to believe there must be a coolant flow restriction issue. So I began by attempting to drain the coolant. And I set a fan on the radiator, and watched until coolant temps had dropped sufficiently before opening the cap and trying to drain the coolant. (I did not care to get a scalding bath/shower of coolant):P

 

After turning the radiator drain petcock full open, the coolant was only dripping slowly… :mad: Hmmm I thought to myself, perhaps I'm onto something… There may indeed be a coolant blockage.:( After finally getting the petcock open and coolant draining (it required the use of an air-nozzle stuck to the petcock to free it), I discovered that the inside of the radiator was squeaky clean, almost as if it were brand new… Hmmmm… :confused:

 

As long as I had the coolant drained, I figured I might as well check the thermostat. So I removed it, and tested it by placing it in a pan of boiling water. A-HA !!! Eureka, and all that !!! I found the problem…:P Blocked cooling flow… (or so I thought…):rolleyes:

 

The thermostat was indeed defective, as even after 5 minutes in boiling water it had only opened approx 1/16", or about 15% of the travel it should have had. A quick trip to the parts house for a NEW 195 deg t-stat and gasket. HOWEVER, before I installed it, I wanted to verify that the NEW one was good… So it AND the old one went back into the boiling water, and VOILA… The New one indeed opened almost immediately to full travel opening, while the old one was still struggling to open at all…

 

After replacing the t-stat, it was time to verify with a test/eval run that I had cured the cooling deficiencies, so off I went. This run demonstrated that I had made another improvement, but that the temps were still climbing to unacceptable levels, even though it was taking longer to do so than either of the previous runs.

 

This got me to thinking about the fan, and it suddenly dawned on me that I had yet to hear the "signature roar" of the fan clutch engaging, and causing the fan noise (roar) which is almost a dead giveaway that the fan clutch is operating correctly. :o(I'm claiming senioritis on the lack of catching this sooner…) :rolleyes:

 

SO, I pulled the fan and clutch, and disengaged the thermostatic spring, and rotated the valve to the left (counterclockwise), which in turn closes the valve and stops the flow of the viscous coupling fluid, which in turn essentially "locks" the fan and causes it to rotate faster, providing more cooling.

 

After so doing, it was time for another test eval run. This time, the cooling system performed MUCH better than before, but the level of fan noise I was expecting, was never realized, although it was indeed louder than before, indicating it was spinning faster.

 

Off to the parts house again, this time for a replacement fan clutch. And following installation, yet another test eval run.

 

HOORAY !!! Success at last !!! The temps were back in line with what they should be. :D:D:D

 

Since we have another outing planned VERY soon, I'm out of time to re-install the winch for this trip. However, given that its removal had improved the cooling even BEFORE I got to the bottom of what turned out to be what I suspect are the two main cooling issues, my experience, backed up by the earlier test results are enough to convince me that either;

A- the winch does NOT get re-installed

B- a MUCH smaller winch (one that does not block so much airflow) replaces it

C- I fabricate a new winch mounting plate, which SIGNIFICANTLY lowers, and moves the winch AWAY from the grille, in attempts to allow improved airflow around and past the winch.

 

Once the final decision on the above is made, I will re-test and confirm that it's still operating at acceptable cooling performance levels. ;)

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Nice job Steve. Did not know you could disconnect the thermo spring & & still run the fan. One thing I looked for when I decided to replace my front bumper was a bumper that located the winch behind & down into the bumper. Only thing catching air is the solenoid box. Again, good job.....Al

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OB1,

 

 

 

Thanks for a great report & hopefully a solution to the problem. I had a similar event on "Stump Jumper", my 01 TJ a few months ago, This gives me some hope for a solution.

 

 

 

 

Thanks,

 

Larry K.

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nice logical problem solving OB.

 

i think most folks cooling issues are similarly a combination of multiple problems - i.e. there's often not a single silver bullet. i have the same take on the common death wobble issue - usually it's from a combination of modifications and multiple worn parts.

 

i wish Jeep included a more accurate/sensitive coolant temp gauge in most vehicles, or at least a full swing style. the divisions are not spaced equally and it's difficult to determine exactly what temp your really hitting. most of us just know that straight up is perfect but that if the needle is slightly to the right you have to watch it because it might stay there forever or it could suddenly jump to "abandon ship" - but you never know!

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Great post OB. Good logical steps to take if you vehicle is over-heating.

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Very informative, nice and easy to follow.

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The reason I went with the Protofab "low profile" front bumper was so the winch will be tucked down below the grille and in front of the factory steel bumper. Good stuff OB! Don't forget that Clifford had an exhaust obstruction which didn't allow the engine to pump out the hot air and would eventually tax the cooling system. Lean fuel ratios and ignition timing issues can also lead to over-heating. Like K smith said.... no silver bullet.

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Thanks OB1. I took my winch cover off for the drive back from the Mogollon Rim trip as you recommended and it made a difference, enough to where i was able to run the a/c uphill. I cannot remember the last time i changed my thermostat but believe George R&R'd it for me recently.

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nice logical problem solving OB.

 

i think most folks cooling issues are similarly a combination of multiple problems - i.e. there's often not a single silver bullet. i have the same take on the common death wobble issue - usually it's from a combination of modifications and multiple worn parts.

 

i wish Jeep included a more accurate/sensitive coolant temp gauge in most vehicles, or at least a full swing style. the divisions are not spaced equally and it's difficult to determine exactly what temp your really hitting. most of us just know that straight up is perfect but that if the needle is slightly to the right you have to watch it because it might stay there forever or it could suddenly jump to "abandon ship" - but you never know!

 

Sir,

You are correct in observations about factory gauges being nonlinear. I was told several years ago by an engineer in charge of instrument clusters that he could program a factory gauge to read however he wanted.

 

For example, in Michigan when you are freezing your but off on an early January morning you want HEAT. He said the gauges are programed to jump to the first mark very quickly so the customer has the perception that warm air from the heater core will be coming soon. Inversely, the gauges are programed not to be too sensitive on the high end so that the customer doesn't see his gauge move when he is climbing a steep, but fairly short duration, grade.

 

This applies for not only newer vehicles. Many (too many) years ago I was twisting wrenches in a Chevrolet dealership. I was present when a GM factory rep told an unhappy customer that he should consider his temp gauge "an indicator, not an instrument". That's a pretty accurate statement IMHO.

 

Great write up Steve, and as others have said, an excellent example of logical problem solving.

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Excellent write up, OB1. Thank you.

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