Hi everyone,

I took a trip to Moab, UT (from Salt Lake City) this past weekend and ran a couple moderate to difficult trails. I was towing an M116A2 military generator trailer (customized expedition trailer) that is 3/4 ton ~1000 lbs loaded (unhooked it for wheeling).

My XJ always seems to run hot, as I have heard most do, but on the way back my catalytic converter started to smoke. I immediately pulled over and shut off the engine. The coolant in the reservoir was boiling and started to shoot out of the overflow. I was driving around 65 mph on a flat highway outside temp was 85-90 deg F.

After about 20 minutes, I determined that I lost about half the coolant. I filled the reservoir and started driving. With the heater at full blast, I made it to Price without any further incident. I stopped a couple more times to let the engine cool and made it home.

My question: is that normal? I just bought a transmission cooler (B&M 7026), a 195 deg thermostat, and a new radiator cap. Is there anything else I should do?

1995 Jeep Cherokee XJ
Straight 6 (V6, 4.0)
4.5" lift, 32" BF Goodrich MT

Thanks!

 

Water pump, fan clutch and radiator?????? Is the fan shroud intact/in place. Any recent cooling system maintenance?.....other than that mentioned. Lots of 19 year old vehicles have overheating issues if the cooling system has been neglected. Towing with big/tall tires is a killer.

 

Thanks djb383. I bought the XJ a year ago, so I am not sure about the cooling system maintenance. I have not done anything. I have put about 5k miles on it (it has 135k on it).

This weekend I am going to install the transmission cooler, thermostat, radiator cap, and upper and lower radiator hoses. I am also going to flush the coolant, clean up the radiator, and replace the transmission fluid. Depending on how brave I am, I might install a hood vent.

I will eventually replace the radiator, water pump, and fan clutch. I will take a look at them to see what shape they are in and if they have been replaced recently.

Thanks!

 

Service and repair THEN once things are working correctly MODIFY.. That means fix the overheating issue BEFORE you start upgrading the cooling system.. Yes you can and maybe should buy upgraded parts to fix issues. But adding upgraded parts to a BROKEN system, any system, can lead to further damage and early failure of your nice new modification.

 

Hmm . . . that does make sense. It seems like the water pump and radiator are working fine and the fans turn on. I am just not sure how to determine if they need to be replaced.

The XJ has never overheated before (it was the first time I towed the trailer). I read that a trans cooler was a good idea for towing so I thought that was a good place to start.

I am trying to troubleshoot the cause of the problem and thought a new thermostat would also help.

 

Unless u enjoy draining and refilling coolant each time u replace a part, replace them all at once, especially since u do not know what kind of maintenance the PO did. I can almost guarantee u will ask yourself, when replacing the water pump, "why in the heck did I not replace the water pump WHEN I replaced the t-stat"?

U can't see inside the XJ rad therefore u can't tell how many rows/tubes r plugged solid. A garden hose flush WILL NOT UNPLUG rows/tubes that r plugged solid internally. If only half of the rows are unplugged, the rad will appear to flow freely, but u only have half a radiator flowing freely/cooling the motor and half won't cut it. The tanks must be separated from the core so the tubes can be "rodded" out and only a rad shop can do that. <$250 in parts buys a complete new cooling system. U've already spent $50 of the $250 on new parts.......don't stop there, git 'er done.

The really hot weather is almost here and the XJ cooling system IS NOT an area where u want to cut corners/half ***** maintenance.

 

If there is one thing you need to to pay close attention to, It is the cooling system on these jeeps from what I have read.. I have had my jeep for bout a year now and entire cooling system is new and in perfect working order..

When I bought my 99 jeep cherokee sport 4.0/4x4 it was a mess, It had a cracked head and the water pump was so rusted it had no fins at all.. I can honestly say it was the worst water pump I have ever pulled from a motor..

I suggest you refresh the entire coolong system, If you have not done any serious damage yet ofcourse..
This way you will know the entire cooling system is up to par.. It is not that expensive to do as long as you do the labor.. And then you dont have to worry bout it over heating any longer.. I am not one for thowing parts at our jeeps but the cooling system is crucial on your heep, and lets face it, You don't know the last time the cooling system was refreshed..

Just my thoughts..

Ant....

 

R these pics of your water pump? I just kinda shrug my shoulders when I read a post that says "water pump looks ok" along with "radiator looks ok". LOL

 

Awesome! Thanks for the information.

 

Ha no those aren't my pictures, but I wouldn't be surprised if they looked similar. I just meant that they seem to be working fine since there aren't any leaks, but honestly I have no idea. I am trying to avoid replacing parts that are not for sure broken, however, it sounds like it is a good idea to just replace the entire cooling system all at once.

 

Dumb question:

Is there an accurate way to tell if you have the original radiator and water pump?

 

The water pump in those pics didn't leak.........it didn't pump water/coolant either.

Don't know about the water pump but an original radiator will have a Chrysler logo sticker and part number on it. Here's a pic of the 13 year old (when it was replaced) original in our XJ.

 

Thank you! That is very helpful. I will look for the sticker.

 

What was the coolant temperature at the time you stopped and saw it boiling over? How full was your coolant expansion tank prior to this?

Could be as simple as a partially stuck thermostat. Get one at the dealer. Pay their $20-25 otherwise you may yourself doing it again.

But, like the others have said, a good time to check and replace a number of parts.

I would at least remove the water pump and inspect. If it looks good, put it back in. If not, replace it while you have it out. Water pump gaskets are $2.

Radiator and coolant hoses are good to replace if they are original while you're doing this based on the age. Lower radiator hose to water pump should have a spring inside it.

There really isn't a reason to overheat on the San Rafael Swell. The only vehicle I've ever had a problem with there was one that turned out to have a slightly blown head gasket.

I think the XJ cooling system is fine as long as its in good working order. I-17 from Phoenix to Flagstaff with the A/C on all the way even sitting in traffic, I-8 between El Centro and San Diego, towing a 6x12 double axle trailer across country (trans fluid was still nice and red when I changed it) ...

 

Thanks md21722, well for some reason my XJ doesn't have a temp gauge inside so I have no idea what the temp was. I think it has a light that comes on when it is overheating, but it definitely doesn't work.

I didn't know I was overheating actually. I was about 40 min outside of Price, UT when it happened. Ha I thought something caught on fire at first cause my cat converter was smoking really bad. I immediately pulled over and turned off my engine.

I regularly check all my fluids, so the coolant was full. Once I got the hood open, the coolant tank was shaking and I could tell the fluid was boiling. It started to spill out of the overflow. The cat converter stopped smoking after a couple of minutes.

I did buy a new thermostat so hopefully it is that simple.

That was the first time I have pulled the trailer.

Last year, I tore out all the carpet and put in new floorpans due to rust, instead of putting the carpet back in, I monstalined the inside. The area near the four wheel drive lever and the center console always gets extremely hot (directly above the cat converter). I have always thought that the heat is normal and I just made a mistake removing all the carpet and insulation—I am definitely happy with the monstalined tub though.