1989 Cherokee Overheating

[atticus3600s]

I have a 1989 Jeep Cherokee XJ 4WD with the 4.0 liter with 155k miles.
The truck overheats when towing the boat on any type of hill, on larger grades I am forced to stop halfway up to allow the engine to cool off so it wont overheat.
It does not appear to have the trailer towing package but Im not towing that much weight. The boat is a 1984 Skeeter SS-Fisherman 16' fiberglass bass boat with a 75 horse 2-stroke mercury. Fully loaded with 12 gallons of gas and 3 batteries and trailer I think the whole rig weighs about 1400-1500 pounds.
The vehicle is rated to tow 2000 pounds without the trailer package (5000 pounds with) and I dont think I am near that at all.
I have basically replaced all the hoses, the waterpump and flushed the cooling system.
Should I install a 4 core radiator, a tranny cooler, or both?
Does anyone have any ideas of what else could cause this problem?
Thanks for your help.

 

[WTPhantom309]

Re: 1989 Cherokee Overheating

is the outside of the radiator clean? if it is id remove the radiator and take it to a radiator shop and have them rod it out, ports could be clogged. used to work on trucks and they would have the same problem and i found out the hard way that no amount of flushing can get it all out. good luck


Derek


P.S. it might be cheaper to buy a new core.

 

[tashasdaddy]

Re: 1989 Cherokee Overheating

i think loaded you pushing at least 1800lbs, what about the thermostat. living in Calif, if your not running antifreeze, the water out there eats cooling systems. when i live in SanDiego, my radiator went in 1 year. had to be replaced it was so clogged.

 

[atticus3600s]

Re: 1989 Cherokee Overheating

Thanks for the quick replies guys,
It looks like I will probably need a new radiator because the one that is in the truck is the original (I think).
I am running a mix of 50% water/antifreeze in my truck and the t-stat was replaced with the water pump and hoses (about a year and a half ago).

Tashasdaddy: Do you really think that boat weighs 1800 pounds? I thought a little bass boat like that was relatively light, but you are probably right and I should really get the whole rig weighed.

 

[JUSTINTIME]

Re: 1989 Cherokee Overheating

i would go with the 4 core and also run wetter water by redline
i have used that stuff and seen a 15 degree drop on my durango while pulling

 

[JB]

Re: 1989 Cherokee Overheating

I think daddy underestimates the weight. I'd say that there is a 50-50 chance that the true weight will be a bit over 2,000.

If so, you need higher gearing, a tranny cooler and a HD cooling system. . .OR, you have an excuse to buy a new truck.

 

[Silvertip]

Re: 1989 Cherokee Overheating

As for the weight thing, consider that my 17 ft Alumacraft Navigator weighs 900# bone dry. Add two batteries (100#), a 325# motor, 150# of fuel, trolling motor, about 200# of gear and accessories and a 400 pound trailer and you are over 2000# in a heartbeat. The radiator has an internal oil cooler for the transmission as well. If the tranny oil is getting hot, that adds to the cooling load on the radiator. If the radiator is already stressed, an overheat can occur. An external tranny cooler may help relieve some of the stress on the too small radiator. By all means run 50/50 mix antifreeze. It raises the boiling point. Straight water is a no-no in any vehicle these days. Your Jeep probably has a 195 thermostat as well. They are cheap so try a 160 or 180 and see if that helps. Clear the bugs and other debris off the A/C condenser too. Make sure the viscous fan clutch is working. Another consideration would be to add an electric fan in front of the radiator if there is room.

 

[atticus3600s]

Re: 1989 Cherokee Overheating

I think daddy underestimates the weight. I'd say that there is a 50-50 chance that the true weight will be a bit over 2,000.

If so, you need higher gearing, a tranny cooler and a HD cooling system. . .OR, you have an excuse to buy a new truck.

I guess that I am looking at more weight than I thought in which case I should probably replace the radiator and then maybe try a tranny cooler if the problem persists. The tranny is cooled by the engine coolant so the combination of the two working hard is probably too much for the inadequate-without-a-boat Jeep cooling system.

In terms of a new truck-I wish, but at 17 and in high school the budget is limited. I am trying to save some money so that by the time I graduate hopefully I will able to get a chevy/gmc silverado/sierra 1/2 ton so that I can get a bigger boat to fish more tournaments.

 

[Silvertip]

Re: 1989 Cherokee Overheating

Before spending bucks for a radiator, make sure the one you have is free of bugs and debris. I assume the vehicle has A/C so the condenser would catch most of the bugs thus blocking air to the radiator. Gear ratios also have a bearing on how hard an engine needs to work. Ring gear and pinions are expensive to change since you have one at each axle. Regardless, you are not towing a great deal of weight so what you have should not be a problem is the cooling system is up to snuff. Just a thought -- you didn't put huge oversize tires on this vehicle did you? If so, you effectively lowered the axle ratio making the truck work harder.

 

[bruceb58]

Re: 1989 Cherokee Overheating

More than likely, your radiator is clogged up. Either take it and get it rodded out or get a new core put in it.

Check your fan clutch and make sure it is engaging.

Check your ignition timing and make sure it is advancing. Running with retarded timing will raise the operating temp.

 

[atticus3600s]

Re: 1989 Cherokee Overheating

I have already cleaned the ac condensor and the front of the radiator of debris. The fan is a viscous clutch type that appears to be working fine, also there is an electric fan that is thermostat operated that comes on when the engine hits 210 degrees and shuts off once it is back to 200.
The tires/wheels/suspension are all stock, not sure of the axle ratio if anyone has experience with Jeep could you tell me the axle ratio?
It is a 1989 Jeep Cherokee Pioneer with the 4.0 liter and 4WD.
The rear axle is a dana 35.

 

[Zackman]

Re: 1989 Cherokee Overheating

atticus, I had the 4.0 L in a 98 grand cherokee and towed more than 4000 lbs without any issues. As others have alluded, something in the cooling system is not right. You may want to try flushing the entire cooling system to ensure that there is no blockage. 89, as you know, was 18 years ago, which is a long time.

I had the towing package in the GC, with a 3.73 axle ratio. Without the towing package the ratio was around the mid 3s.

Jeep XJs came in several standard gearing ratios:

3.07:1, manual transmission, I6 engine.
3.54:1, automatic transmissin, I6 engine with DANA 44 rear differential.
3.55:1, automatic transmission, I6, V6 engines.
3.73:1, automatic transmission, I6, Tow Package, UpCountry Package.
4.10:1, standard transmission, automatic transmission, I4 engine.

 

[atticus3600s]

Re: 1989 Cherokee Overheating

Thanks for all the great responses guys!

Well, I probably have the 3.55 ratio which is not bad but not as good as a 4.10 would be in the truck, the upside is the fact that I can get 23 MPG on the highway with this thing.

I have flushed out the cooling system when I put in the water pump and it didnt help anything. Part of the problem is probably that it is old and before I got it (2 years ago) it sat in a driveway for two years and was never run in that time period. Thats part of the reason I got a good deal on the truck.
The cooling system is probably pretty corroded and needs more than a flush to really remove all of the deposits.
At the moment I am looking into getting a new radiator but am still open to more suggestions.

 

[DJ]

Re: 1989 Cherokee Overheating

If you're going to get a new radiator, see if you can "super size" it.

 

[WTPhantom309]

Re: 1989 Cherokee Overheating

id take it to a radiator shop they could tell you if it was worth rodding or junking. have had alot of experience with that cause all the shade tree's out here insist on using a water hose to fill their motors with and we have really salty water, salt heat andelectrolisis ar killer on alluminum

 

[DJ]

Re: 1989 Cherokee Overheating

West Texas,

I agree. I'm in Arizona, there a loads of minerals in the water here.

I fill mine with distilled water. So it costs two buck$-no big deal.

 

[hal2814]

Re: 1989 Cherokee Overheating

89? Did that have the old style (with huge plastic bottle) radiator on it? There's a conversion guide online somewhere for the newer (and far more reliable) cooling system used in later 4.0L Jeeps. If you have to replace anyways, you may want to look into that. My mechanic did that conversion on my old YJ when the original radiator crapped out on me. It ended up costing just a little more than swapping out the original parts and I never had a temp problem again after that (though I never towed with it).

 

[atticus3600s]

Re: 1989 Cherokee Overheating

89? Did that have the old style (with huge plastic bottle) radiator on it? There's a conversion guide online somewhere for the newer (and far more reliable) cooling system used in later 4.0L Jeeps. If you have to replace anyways, you may want to look into that. My mechanic did that conversion on my old YJ when the original radiator crapped out on me. It ended up costing just a little more than swapping out the original parts and I never had a temp problem again after that (though I never towed with it).

It has the coolant reservoir that is pressurized with a pressure cap on it. The radiator does not have a standard pressure cap like most trucks probably due to the fact that the top of the radiator cannot be easily accessed from the top of the engine without removing lots of stuff.
The conversion sounds like a good idea but I dont know if I want to put more money into that truck than is absolutely necessary.

 

[BoatBuoy]

Re: 1989 Cherokee Overheating

Had a similar problem on a Ranger. Removed radiator and took to radiator shop for rodding, etc. Replaced water-pump, thermostat, all hoses, new coolant, new fan belt - still ran hot. Finally installed a $12 mechanical temp guage from Pep Boys only to find out everything was OK. It was the silly factory instrument cluster that was messed up.

 

[WTPhantom309]

Re: 1989 Cherokee Overheating

all this mechanicing is making me thirsty i need a beerd8)