Over heated Jeep

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Tom P

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I used my 1999 Jeep Cherokee to trailer today for the 1st time with down the NY Through-way about 50 miles (exit 17 to route 17 in NJ) . I was pulling a single axle trailer, with a 3,500 lb payload (boat + gas). On flat land I didn't have any problem. But on uphills, the Jeep over heated (gauge almost pined - 90%) . I turned on the heat and the gauge went down on the down hills. Basically, I had to ride halfway home with the windows down and the heat on full blast to keep the jeep from over heating.

I've made the exact same run, with the exact same boat and trailer using my 1996 jeep and that never happened, Any thoughts on how why the newer jeep is over heating? Or, does anyone have any thoughts on how to keep the temp down.

Thanks much,

Tom
 
MRS

MRS

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Re: Over heated Jeep

Usallly a bad stat. or radiator needs cleaning.....
 
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Tom P

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Re: Over heated Jeep

I should have mentioned. The jeep just got (less than 2 months agos) a new water pump and a new themostat. Could it still need a flushing?

Tom
 
JB

JB

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Re: Over heated Jeep

What is the tow rating of your '99 Jeep as equipped? Have you actually weighed your load? Does the trailer have brakes?

My guess is that you are overloading it. You might need a diff gear change, an oil cooler and an aux. cooling fan.
 
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bbofasho

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Re: Over heated Jeep

more then lickely its yur fan. the fan clutch to be honest. normaly they sell a heavy duty one and a regular one. that im shure will fix it and if it still rises a little more then half u can add a electric fan that u can turn on when yur towing.
 
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Jeepster04

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Re: Over heated Jeep

Usually if the Jeep is over heating while at hw speeds theres only a few things it can be. The water pump, clogged radiator, or a tstat. If its over heating while idling then the cooling fans would be added to that list.

You could also check for a bad radiator cap. Always a good cheap place to start.
 
MRS

MRS

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Re: Over heated Jeep

Tom P said:
I should have mentioned. The jeep just got (less than 2 months agos) a new water pump and a new themostat. Could it still need a flushing?

Tom
Click to expand...

Yup, plus who changed the pump and stat? If not you the radiator could just be bad pinched off cores....
 
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northernmerc

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Re: Over heated Jeep

An easy first thing to look at is the exterior of the radiator. If the cooling fins have bugs, dirt, grass, etc. jammed between them, the radiator won't cool properly. Depending on the radiator and how much room you have to work with, you can either wash or blow the crud out. In some cases, you may need to remove the radiator and/or shroud to get at it.

This happened to me with a GMC 454 pulling an 8,500 lb trailer. It overheated badly until I cleaned the exterior of the radiator. After that, it ran cool.
 
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windsors03cobra

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Re: Over heated Jeep

Was the 96 a Cherokee as well or was it a Grand ? The radiator in the Cherokee is tiny and what you are experiencing has been a known problem for 2 decades.
I agree with the probably overloading it theory.
I also agree that you could have a fan problem, 2 fans on that Jeep, is that stupid snow flap still intact under belt and radiator area maybe thats holding in extra heat.....:cool:
 
woosterken

woosterken

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Re: Over heated Jeep

when the pump and tstat. werechanged was the system blead ? it mite have air traped in the block or rad.

woosterken
 
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Tom P

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Re: Over heated Jeep

I?m going to start with the easy fixes by cleaning the radiator inside and out. Both my 1996 & 1999 Jeeps were Classic Sport Jeeps. The difference between the 2 are the 1996 was black the 1999 is red and doesn?t smell like fish yet. The boat hasn?t changed. The trailer hasn?t changed. It sounds like if that doesn?t fix the problem, the next step is to add an electric fan.

To flush the cooling system, is that something best done at a Jiffy Lube type place or will draining the antifreeze and running water through the system do the trick.

Thanks,

Tom
 
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DJ

Guest
Re: Over heated Jeep

My money would be on a clogged radiator.

Flushing rarely fixes that. That might Band Aid it but not fix it.
 
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Silver Eagle

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Re: Over heated Jeep

What size engine do you have? Do you have a trailer towing package.? or at least a transmission cooler on it? That can makke a big difference in over heating. Chrysler products have a button on there shifting lever for towing, If you have it use it. Do you have an electric fan or belt driven.?Take a garden hose and spray it into the radiator.
 
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HappierWet

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Re: Over heated Jeep

You'll have both a clutch driven fan and an auxillary electric fan. Check the relay and fuse for the electric fan. Also, do you have an aux. trans cooler?
My '90 XJ would overheat just from the trans til I put a cooler in front of the radiator. Do NOT tow that kind of weight in Drive. See the thread about why towing in Overdrive is bad. Check the trans fluid. Maybe add extra antifreeze to the rad.......

Let us know what you learn. :)
 
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Tom P

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Re: Over heated Jeep

I had a trans cooler in my 1996 Jeep and I have one in my 1999. I never tow in drive. I always tow in 3rd. There are two fans in the 1999 Jeep. One is electric and I believe one is belt driven. I?ve seen them both fans on. I think they alternate.

I think making sure the front is clean and that the radiator isn?t clogged is the 1st order of business. Cleaning then outside of the radiator seems simple. What?s the best procedure for addressing a clogged radiator?

Tom
 
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eli_lilly

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Re: Over heated Jeep

DJ said:
My money would be on a clogged radiator.

Flushing rarely fixes that. That might Band Aid it but not fix it.
Click to expand...

I'm on my third XJ and I've replaced the radiator in each one almost immediately after purchase. The one I just got overheats when I tow the boat and I'm dropping in a heavy duty radiator in a few weeks.

-E
 
smokeonthewater

smokeonthewater

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Re: Over heated Jeep

eli_lilly said:
I'm on my third XJ and I've replaced the radiator in each one almost immediately after purchase. The one I just got overheats when I tow the boat and I'm dropping in a heavy duty radiator in a few weeks.

-E
Click to expand...

drain the coolant including the drains for the block... flush a couple times with water and then add a flushing agent from the parts store... run it for a bit... get it hot pulling a load... get the rpm's up while it is hot... then drain and flush with water again.... now the gunk should be out of your engine block and you can toss the old rad in the trash and drop in a new hd version... can be had for as cheap as about $100.... If you still have probs then look at fan, fan clutch, head gaskets, water pump, and transmission problems..... a slipping tranny can cause overheating probs quickly in a vehicle with a marginal cooling system...... such as a cherokee

Also that "stupid snow flap" is actually designed to keep the area behind the radiator under low pressure at highway speeds and increase air flow through the radiator.
 
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srimes

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Re: Over heated Jeep

What RPMs were you turning? Run to slow and you're more likely to overheat. Don't use overdrive, and downshift to 2 on big hills. You should never be below 2k rpm when you're on the gas, and on big hills 3k is better. I have a 99 xj as well, and while the 4.0 has plenty of torque it really likes to spin a little when under load. When pulling a big load up a hill I keep it around 3k-3.5k.

Make sure you have a tranny cooler if you want it to live!
 
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windsors03cobra

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Re: Over heated Jeep

Tom P said:
What?s the best procedure for addressing a clogged radiator?
Click to expand...

eli_lilly said:
I'm on my third XJ and I've replaced the radiator in each one almost immediately after purchase. The one I just got overheats when I tow the boat and I'm dropping in a heavy duty radiator in a few weeks.

-E
Click to expand...

I guess the XJ Guru has spoken. From sunny FLA no less, land of a thousand overheat tests.

Sorry about that low pressure creating flap but that stupid thing is always tore up, junked up and hanging all over.
He said he tows in 3rd which is sweet with that tough as nails Toyota trans. ;)
The 4.0 dont mind to rev a little, love that old Kenosha built AMC six.
 
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fishrdan

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Re: Over heated Jeep

What engine do you have?

bbofasho said:
more then lickely its yur fan. the fan clutch to be honest.
Click to expand...

I'm betting on the fan clutch too. When it was overheating did you hear the engine driven fan clutch engaging, loud roaring noise like there's a tornado under the hood?

I had to replace the fan clutch on 2 dodge trucks so far (4.7L) because of overheating problems,,, and now need to replace the one on the Durango as it's gone bad too. The fan clutches were not leaking or visibly bad, but they did not operate like they should, IE: lockup when they get hot.
 
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