Better cooling for the Comanche?

[johnj92131]

Yesterday, I was towing 3500 lbs with the Comanche. Outside temp was 95 degrees in Los Angeles area. My coolant temp got up to a sustained 230/235, just below the red.

 

The truck has the full, factory towing package which includes all heavy duty cooling options.

 

Once I quit towing, cooling returned to normal.

 

Should add that my cooling system is in top notch condition. Problem seems to be simple heat build up in the engine compartment.

 

What are my options here? Yes, buy a bigger truck is one.

 

Really asking best ways to vent hot air from the engine compartment. Know about hood vents Don uses. Does anyone "lift" the rear of the hood to vent the engine compartment?

[HOrnbrod]

Yes, it's best to vent the hood real estate John. To be honest, I tried two different sets of sets of hood vents, and while they helped somewhat, they were not the ideal solution. The Reflexxion cowl hood I found was the solution and now all is fine. But there's not much chance of finding one of those anymore. So either have a functional steel cowl hood fabbed up (best), or raise the back of the hood up using shims like THESE. Cheap and easy. 

[75sv1]

I'd list your options. Did you miss something? Don't know. Also, might look at ZEREX Z05 coolant. Mix it on the heavy side. Possibly a ceramic header, to keep the heat out of the engine bay. What radiator do you have? Do you also have an oil cooler? I haven't gone that route yet. I don't tow 3500 lbs either. Some used to use LeBaron hood vents. What speeds were you running? A constant speed? Or varied?

[ParadiseMJ]

Actually regular water is a better cooler than anti-freeze, so I'd mix it 70/30 water/antifreeze for summer and some water wetter..might want to richen it up in the winter...if it freezes a lot in LA/SD or for heading to the mountains.  I wouldn't run it without.

 

I have LeBaron vents on both rigs...MJ & XJ...with fabbed drip pans that work well in the winter and even though it almost never rains here in the summer, they still allow a lot of heat out the hood.   But if I had it to do over I'd probably raise the back of hood as Don suggests.

 

...and a couple questions...Do you have a manual or AW4? and if so do you have a big tranny cooler or just the factory two tube one. 

[omega_rugal]

Adding some vents will help, i`m in the process of fabricating a couple for mine...

[Jeep Driver]

First thing I would do is divorce the trans from  the rad. 

 

Secondly, mount this under the bed.

https://www.summitracing.com/parts/der-15820?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-derale-cooling-products&gclid=Cj0KCQjwtpDMBRC4ARIsADhz5O4-uosxiYzDoeTXbXyKwPvHOBg3rsHrtFpBJNflekUFtb8VYwui7YcaAm0AEALw_wcB

[johnj92131]

AW4 with factory BigTon package delivered from factory. Radiator, 2 rows 18 months old. Water pump, thermostat, less than 6 months. Engine temp sensor less than 6 weeks old.

Traffic was typical L.A. mid day freeway. Means, stop/go then 65, back to stop/go.

Radiator is running standard mix water/coolant.

Those aluminum spacers look worth a try.

 

After several years of on/off towing, sure looks like under hood temps just climb with heavy use.

[Jeep Driver]

Here's something for you to read. 

 

With a RHD factory oil "cooling" setup - my tranny sump temps were about 170 - 240 depending on driving circumstances.

Interestingly enough .. the factory provided the baby aux oil cooler as a standard fitting ...... but they did dangle the radiator heat exchanger in the hot side of the radiator to make up for it ... 

Since bypassing the radiator and fitting a pair of factory aux coolers my average temp is 160' .... until I go up a hill or tow something in summer ... and then its back to 220' and the warning buzzer screaming its head off.

 

http://www.naxja.org/forum/showthread.php?t=1037152

 

 

Read his entire post. 

 

 

 

 

I'm suggesting to you that your AW4 was probably in the 240 to 250 degree range which pushed your engine temp up to 235. 

 

Most of our trucks are 27-30 years old, it no longer matters what it left the factory with, it's old and tired. 

[HOrnbrod]

Just open up the back of the hood (or find / fab a cowl hood) and allow the cowl induction to suck the cooler air in. Hood vents won't help much........

 

https://youtu.be/irVDERE7CtU

[Pete M]

just to throw this in the hat because it happened with me (ymmv), but cracking the seal of the hood (I did it for cooling) lets all the stinky smells of the engine bay get right into the cab as I hit 45pmh+.   :(

 

 

 

fortunately my cooling mod wasn't passive and if I hit the fan (which was installed for slow trails) on the highway, the fan pushed the smells forward into the air stream and the stinky-ness stopped :)

 

[johnj92131]

Just ordered the hood spacers.  We will see how they work in September/October if I make a test run up to 4000 feet in the heat.

 

JeepDriver, Read the full thread, thanks.  I am puzzled by why the factory would route the trans fluid thru the radiator IF the trans fluid was supposed to run at 170f.  But all automakers use the radaitor/transcooler combination.  So I suspect the 170f temperature number referenced in the thread is not accurate.  But I do agree that 230 is hot for both the transmission and the engine.  Noticed that the red area on the temp gauge starts about 240 - perhaps for the transmission fluid?

[Minuit]

Was the new engine temp sensor aftermarket or Mopar, and was it for the gauge or ECU? If it's for the gauge you want to verify it. I have experience with multiple aftermarket temp sensors reading 20+ degrees too high on the gauge (compared to the ECU temp sensor read through the diagnostic port). Mopar sensors, while not perfectly accurate to the temp the ECU reports, are much closer to reality. Not saying this is your problem but it eliminates another variable.

[johnj92131]

Minuit,

 

Engine Temperature Sensor was for the ECU.  Had an OBDI blink code error #22.  See posts 8 and 9 in this thread:

 

http://comancheclub.com/topic/53435-diagnostic-help-needed/

 

Replacing the ETC cured my stalling out problem.  The bad sensor caused the ECU to go fuel rich and/or fuel lean on the engine. Depending on where the bad sensor voltage signal bounced.

 

While I don't have a thermometer to check the temperature gauge/sensor - it seems reasonably accurate and responsive to engine load conditions over the past couple of years. That includes some cooling issues I have had that led to repairs/replacements.  One of these days, I will upgrade to OBDII controls and be able to read the ECU directly. 

[Jeep Driver]

Just ordered the hood spacers.  We will see how they work in September/October if I make a test run up to 4000 feet in the heat.

 

JeepDriver, Read the full thread, thanks.  I am puzzled by why the factory would route the trans fluid thru the radiator IF the trans fluid was supposed to run at 170f.  But all automakers use the radaitor/transcooler combination.  So I suspect the 170f temperature number referenced in the thread is not accurate.  But I do agree that 230 is hot for both the transmission and the engine.  Noticed that the red area on the temp gauge starts about 240 - perhaps for the transmission fluid?

You stated that once you quit towing the temps returned to normal, this tells me it was the towing that effected temps. From my own experience, and that of others, AW4s generate a tremendous amount of heat. 

It's one of the things that I have yet to see anyone contribute to the MJ/XJ cooling problems. Automakers produce vehicles to operate within the same parameters regardless of where it spends it life, northern MI or southern FL, or in your case, So Cal. 

Marrying the trans to the rad is designed to bring the trans temps up, not down. The trans will create it's own heat, you are not waking up to 5 degree mornings. 

 

If 'normal' engine temp is 210 (I don't agree that that is normal), and the trans normal temp is 160-170 (I do agree that is normal) then how is the rad ever going to cool the trans? It cannot, it will not. If anything it raises the trans temp. Then, you tax the trans by towing/climbing which does raise the trans temp which in turn taxes the cooling system even more.......vicious circle. 

 

 

I was just looking a rads, my wife's XJ is due for one, I will by local so that I can replace local (same day if necessary) and I just noticed the postal vs left hand........interesting that I noticed this and found the thread that mentioned the postal being on the hot side of the rad https://www.oreillyauto.com/shop/cooling---heating-16773/radiator-20386/radiator-11357/1998/jeep/cherokee?q=radiator

I'm interested in the postal rad, curious if it will fit, 1" taller core, copper, reasonably priced. And yeah, I'll just bypass the trans to a small cooler.......this XJ gets driven maybe 20 miles per week.

[johnj92131]

JeepDriver,

 

Notice that the "Postal" radiator is a 2 core or 2 row radiator and the "non Postal" is a single core or single row radiator.  That would seem to be the major difference. The 7/8 inch height difference is minimal. 

 

You will see some custom 3 core/3 row radiators offered on Ebay.  But all I can read is that they are of no additional cooling value for the XJ/MJ.  My guess - not enough air flow out of the engine compartment to cool the third row.  My own experiment with simply turning off the truck A/C led to a noticeable drop off in engine coolant temperature (maybe 10 degrees?). That also leads me to think a 3rd row on the radiator is worthless.

 

Have you measured your transmission temperatures?  I would be interested in before and after results when you install the trans cooler.

[ParadiseMJ]

First thing I would do is divorce the trans from  the rad. 

 

 

Yes, I agree with this too.  My tranny used to get HOT when I was towing a big grade or driving steep and slow (not towing).  Since the radiator link helps to warm the tranny fluid when ambient temps are low - freezing.  It continues to ADD heat to the radiator when tranny temps start going up.  I removed the hoses sending tranny fluid through the radiator and added a 11x11 tranny fluid cooler...and a trans temp gauge.  My trans temps still get warmer when towing or slow going but only around 180...and on the highway trans temps are under 150 consistently, even in 100+ weather.

[HOrnbrod]

Yes, I agree with this too.  My tranny used to get HOT when I was towing a big grade or driving steep and slow (not towing).  Since the radiator link helps to warm the tranny fluid when ambient temps are low - freezing.  It continues to ADD heat to the radiator when tranny temps start going up.  I removed the hoses sending tranny fluid through the radiator and added a 11x11 tranny fluid cooler...and a trans temp gauge.  My trans temps still get warmer when towing or slow going but only around 180...and on the highway trans temps are under 150 consistently, even in 100+ weather.

Hmmm. I must admit - this does make good sense Charlie. It does go below freezing a few times here in northern Bama, but nothing like up Nawth. I like the idea of keeping the tranny cooler by not heating up the fluid through the radiator. My truck originally had no tranny aux cooler, and I added the little stock XJ cooler like the one below several years ago. It seems to do the job, since I don't tow much anymore and have never had any problems with it getting overly hot. What I like most about bypassing the radiator is that it eliminates two of those potentially leaky quick connectors.

[johnj92131]

ParadiseMJ,

 

Where did you mount the 11 x 11 transcooler?  In front of the a/c condenser?  How did the trans cooler change your engine coolant temperature?  Suspect not at all??  Good information.  Also, did you mount your trans temp gauge on the output side of the transmission?

[johnj92131]

Don, what year did that stock XJ trans cooler come from?  Where did it mount.

[HOrnbrod]

Don, what year did that stock XJ trans cooler come from?  Where did it mount.

 

Mounts on the lower radiator brace - the holes are already there. Here's one on Ebay, but you can find them cheaper:

 

http://www.ebay.com/itm/New-OEM-Replacement-Transmission-Oil-Cooler-JEEP-CHEROKEE-90-01-L6-4-0L-Engine-/251411420160?fits=Make%3AJeep%7CModel%3ACherokee&hash=item3a8949d400:g:4VUAAMXQVERSvFWl&vxp=mtr

 

You can see the factory aux cooler mounted in this pic:

 

[ParadiseMJ]

ParadiseMJ,

 

Where did you mount the 11 x 11 transcooler?  In front of the a/c condenser?  How did the trans cooler change your engine coolant temperature?  Suspect not at all??  Good information.  Also, did you mount your trans temp gauge on the output side of the transmission?

 

The cooler is mounted in front of the aux fan, I don't have functioning A/C (it's on my list though).  The MJ is not my DD.  I don't drive it unless I'm going to the mountains, skiing, camping on days off/weekends.  I have a 40 mile commute every day so I drive a little ricer commuter car, the MJ doesn't make 35 mpg, strictly financial.

 

 I'm not sure if the cooler changed the coolant temp or if not having 250F tranny fluid coursing through the radiator did it.  I haven't overheated, or even gotten over 210 towing a boat or wheeling it but then everything runs cooler since I changed the routing of the trans fluid and installed the cooler. Normal temps. single row OEM radiator.

 

EDIT: but I sure like the idea of mounting the cooler lower so it doesn't interfere with cooling the condenser (when I finally fix that A/C) 

[ParadiseMJ]

Oh, sorry, mounted the trans temp gauge in-line on the steel exit line with a brass T (single wire sender grounds on the line).  If the temp falls drastically it tells me if I have a severe leak or the pump isn't pumping too!

[Minuit]

On the subject of trans coolers John, I think you should add one. I mounted a Hayden 678 in front of the aux fan like this:

I don't tow with this truck (yet) but it's one of the larger models Hayden offers and they advertise it as being suitable for up to 5,000 pound loads on vehicles with GVWR of up to 24k pounds, so something like this would probably suit your needs quite well. My transmission seemed somewhat more responsive once up to temperature after adding it, and I've had no issues after almost a year. I have it plumbed after the radiator to allow the coolant to warm the transmission oil on cold days, but for heavy towing I'd probably leave the radiator out entirely, which would take the heat load of the transmission off of the radiator. I noticed no meaningful change in A/C efficiency or engine temps after adding the cooler, but as I said I don't tow. In a towing situation where the transmission fluid gets very hot I imagine there probably would be at least some difference.

 

Sadly I didn't have the foresight to measure transmission temps before and after, but I do know that this particular AW4 has overheated before, and this truck has never towed anything bigger than a lawnmower in its life. I agree that the AW4's cooling is lackluster at best, and I'm not sure how much the small serpentine factory cooler would help for frequent towing.

 

BTW: my radiator is the CSF 3-row, and the engine runs at 200-205 no matter what (ECU temp, not guessing based on looking at the gauge.) With the factory radiator I had wild temperature swings, especially upon coming to a stop after driving on the highway. That's my experience, and yours may vary, but switching to the 3-row radiator greatly improved my cooling.

[HOrnbrod]

How did you mount it? With those zip tie thingies?

[Strokermjcomanche]

Most of the Hayden's use this for mounting

 

https://m.summitracing.com/parts/hda-210?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-hayden-automotive&gclid=EAIaIQobChMIwJyMtfHC1QIV00wNCh2_MgNhEAQYAiABEgLJaPD_BwE

 

And here's a link to the dorman factory replacement trans cooler

 

http://m.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR1.TRC0.A0.H0.X918-25.TRS0&_nkw=918-251