I will start with the basics. I have a 98 Cherokee with 4.0 and aw4.

I never had over heating issues until recently. I discovered my radiator cap was bad so I replaced it. This seemed to cure the problem. I could run all day with the ac on when it was 110 Degrees outside and never get above 210 Degrees on the gauge.

Unfortunately my stock radiator couldn't hang with the new found pressure the radiator cap was allowing to build and it blew while I was pulling a grade on a hot AZ day. Even more unfortunate is the fact that I lost my engine during this event.

Now I have installed a long block from ATK, a csf 3 core radiator, a flow kooler waterpump. I drove for just under 200 miles and it starts to get hot in overdrive and with the AC on. If I kick it out of OD the temps drop to about 210. It seems to have the hardest time staying cool at highway speeds so I don't think it is a fan issue. It used to run under 210 except for big hills and extremely hot days with the AC on. Any ideas?:confused:

Just a few things to consider... This may not make sense to you but what part of the cooling system have you NOT replaced? Are you running a fan-shroud? Could it be your fan clutch maybe? Doesit have good resistance when you try to free-wheel it by hand when the engine is off?

If it's not disengaging it can dam the air and if it's free-wheeling too much it may not be pulling the air in when you need it. Fan clutches are designed to pull air in at lower rpm's, and they disengage at about 2,500-3000 rpms of engine rev. Is your auxilliary fan kicking on at 115 like it's supposed to? Another thing to remember with a new engine is particles and crud from the machining is still in the water-jackets and could be clogging your new radiator, seen it happen before. Is your heater working properly? SOmetimes you can have an air-pocket in the heater core as well.

Mine is doing the same thing, doesn't like hills either, gets up to about 215-220 then cools down once I get my foot out of it for a while and/or coast it for a while. I'm kindof curious what you come up with on this. I don't have a fan-shroud though so I'm thinking that's my problem. This is my 3rd Cherokee and none of the others had a problem at all. I've heard tails, and I guess my number is up finally. Good luck and I'll check back to see what you come up with. There has to be a reasonable explaination.

I have not replaced the heater core, the mechanical fan, or the electric fan. I don't think it is a fan issue though because it is fine at low speeds, which is when the fans are needed. I do have my factory fan shroud in place. The engine is a reman so there shouldn't be any casting particles in there. My heater is not working. In fact it has never worked since I have owned the Cherokee. I think I answered all of your questions. I am going to test my new cap to make sure it is still good and I will replace my t stat, t stat housing, and temperature sensor when they arrive from Turbo City. I also wonder if it is not running as hot as my gauge is saying? If anybody has any ideas I am open to them.

How hot is yours getting? 215, 220, 225, more??

Keep in mind these cooling systems SUCK and don't have much room for margin/error. It could be very well be a fan problem. Remember, when you're climbing a hill your engine isn't pulling as much air as if it were on flat-land in comparison to the amount of strain you're putting on it. You sure your electric fan is kickin on at 215 like it's supposed to? Your engine is revving up, you're in a lower gear, and youre not going all that fast. 55 MPH up a hill at 4000 rpm's may not be sufficient enuf airflow if that second fan isn't running. 50% of your radiator is cooled off by that puppy.

Hey, this may sound silly but have you taken your hood off for a day and see if it fixes the problem? Once I get my fan shroud installed, if it doesn't fix it then that is something I've been thinking about doing on mine just for kicks. There are some gaskets/weatherstripping at the rear of the hood that can be removed to allow a little more heat dissipation, and a lot of guys put vents in the hood. Not enuf airflow under the hood on these.

Your guage could be bad, too. Most auto shops have an infrared heat-gun and may let you use it if you're nice and buy 'em lunch or something. Point the gun at the thermostat housing and both sides of the radiator at the tanks and see what you get in comparison to your guage.

Here's some great tips for "beefing up" the cooling system. I know a guy that put a 180 thermostat instead of a 195, and hard-wired his electric fan so it runs all the time, or controlled by a switch, It eliminated the problems all together.

A 98 should have the filler neck on the radiator.

Did you get all the air out of the system? Any idea what your tranny temps are? Since the stock setup use part of the radiator to cool the tranny fluid you could be getting some extra heat from there. Although it seem odd to happen all of a sudden though.

What about youe t-stat? Have you replaced it yet? Use a dealer one if you do as the other brands seem to be hit or miss.

He also put a 180 thermostat instead of a 195,

Your computer will stay in the default fuel settings and not use the sensors to meter it properly if the engine doesn't get to 200-210 and your mileage will suK.

A 98 should have the filler neck on the radiator.

Did you get all the air out of the system? Any idea what your tranny temps are? Since the stock setup use part of the radiator to cool the tranny fluid you could be getting some extra heat from there. Although it seem odd to happen all of a sudden though.

What about youe t-stat? Have you replaced it yet? Use a dealer one if you do as the other brands seem to be hit or miss.

you're correct, I was thinking he had an '89 so I changed my post so not to look lke a dummy. The filler style is definitely better than the bottle, like my '89 has. The bottles break and the system can't purge air for crap!

My thermostat and thermostat housing shipped today. I should get them this week. I will update everyone when I get it installed. I also bought a new temperature sensor that I will install in the new housing when it arrives. Another interesting fact I didn't mention before is when it was running about 220 the other day I pulled into my driveway and let it idle for about 10 minutes or less. The temperature dropped to just under 210 while it was idling. I have worked a lot of overheating problems but never one like this. It is very strange.:confused:

I had this problem with the wifes old XJ. Would only do it in overdrive. New radiator, fan clutch, water pump. Turned out to be the trans. I'd say have it looked at and flushed and fresh oil and filter. I since sold that one and got her one with an AX15.

What was wrong with her transmission and did it have any other symptoms?:beer:

yes i am curious about this as well. i've got the aw4 in mine and starting about a year ago i've had overheating problems running on the highway over 60 mph. anything under runs amazing... even trail riding! it only climbs over 215 and near the "red zone" past 60. everything has been replaced except for the radiator and hoses.

yes i am curious about this as well. i've got the aw4 in mine and starting about a year ago i've had overheating problems running on the highway over 60 mph. anything under runs amazing... even trail riding! it only climbs over 215 and near the "red zone" past 60. everything has been replaced except for the radiator and hoses.

..sounds like this guy needs a radiator. Here's one for ya... I'm on XJ #3 now and it's the only one that has the problem which sounds similar to everyone else's. It's also the only one that doesn't appear to have had the radiator replaced! Note, I also blew some of the bugs and junk out of the fins on mine and it helped but didn't fix it. I still get up to 220-225 if I push it really hard up a hill on the highway.

You might try putting a tranny cooler before it goes to the radiator tranny cooler.

kiss this thread goodbye as soon as this forum gets a mod. this is hardly newbie tech

kiss this thread goodbye as soon as this forum gets a mod. this is hardly newbie tech

Do you have the answer to the problem? :shaking:

Hey! I have the same problem as yours. I thinks that it is the common problem of 98 Cherokees. Autopartswarehouse.com (http://autopartsware.tabulas.com) helped me with this. I am gonna recommend. Hope I helped. :)

The trans didn't feel like it was slipping, or anything bad like that. I did service it. From the trans guys, they said it had to do with the lockup tourque converter. I am not a trans guy but after having the trans rebuilt it never did overheat again until we sold it.

That sucks. I hope I don't have to rebuild my trans now! Hey Irok Cherokee are you in Prescott AZ?

Yup

..sounds like this guy needs a radiator. Here's one for ya... I'm on XJ #3 now and it's the only one that has the problem which sounds similar to everyone else's. It's also the only one that doesn't appear to have had the radiator replaced! Note, I also blew some of the bugs and junk out of the fins on mine and it helped but didn't fix it. I still get up to 220-225 if I push it really hard up a hill on the highway.

So much had already been figured. Was just curious to see if it fit in with the mold. This info is good if the new rad doesn't make things peachy.

Ive had this in both my cherokee models a 91 and a 94,, both got replaced with 2 core radiators and new water pumps and 195 deg thermostats.. both ran excellent ..IMO the 4.0 doesn't like fancy setups IE aluminum and 3 core stuff..seem to work great with a nice CLEAN rad and a good water pump

115 deg weather is not nice

Ive had this in both my cherokee models a 91 and a 94,, both got replaced with 2 core radiators and new water pumps and 195 deg thermostats.. both ran excellent ..IMO the 4.0 doesn't like fancy setups IE aluminum and 3 core stuff..seem to work great with a nice CLEAN rad and a good water pump

115 deg weather is not nice

Good info, and sounds like a reasonable place to start.