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jeep grand cherokee troublesome overheating


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dmac0923
Enthusiast

Aug 9, 2011, 9:19 PM

Post #1 of 6 (2494 views)
jeep grand cherokee troublesome overheating Sign In

2003 Jeep grand cherokee 4.0 auto 4x4
137,000 miles
this question i am relaying for a buddy that approached me about it.

the jeep is overheating after about 20 min of run time. it happens both when parked idling and on the highway.

the radiator is full and the coolant in the radiator neck doesn't have bubbles or oil in it. thinking a possible bad headgasket

the lower hose heats up as normal and i can feel the upper hose get hot after it reaches operating temp suggesting the thermostat is opening correctly.

the fan comes on and off normally.

any ideas? this one has got me stumped
__________________________________________________
2015 Jeep Grand Cherokee
2002 Ford Ranger
2004 Toyota Corolla
1969 Ford Mustang Mach 1


Sidom
Veteran / Moderator
Sidom profile image

Aug 9, 2011, 9:54 PM

Post #2 of 6 (2486 views)
Re: jeep grand cherokee troublesome overheating Sign In

Just off the top of my head I would probably want to make sure the radiator isn't restricted. If you have a temp gun, measure the inlet & outlet temps you want to see at least a 40° difference. If you can get at the cores, make sure there are no cool areas, that would indicate restricted flow

If he hasn't change the T stat in a while it wouldn't hurt to put a good one in, just to make sure it isn't restricting the flow to much....

If you have the means, maybe chemical test the cooling system to be positive no exhaust gases are getting in there


dmac0923
Enthusiast

Aug 10, 2011, 2:00 AM

Post #3 of 6 (2479 views)
Re: jeep grand cherokee troublesome overheating Sign In

I forgot to mention that turning the heat on in the car will help return the temp back to the normal operating range and will stay there as long as the heat is on
__________________________________________________
2015 Jeep Grand Cherokee
2002 Ford Ranger
2004 Toyota Corolla
1969 Ford Mustang Mach 1


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Aug 10, 2011, 4:44 AM

Post #4 of 6 (2467 views)
Re: jeep grand cherokee troublesome overheating Sign In

What does the coolant look and smell like?

Sidom has some good ideas that you should have your friend try out.

Radiators can corrode from the inside and look perfectly fine from the outside, but they won't conduct heat very well.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


dmac0923
Enthusiast

Aug 11, 2011, 10:03 PM

Post #5 of 6 (2436 views)
Re: jeep grand cherokee troublesome overheating Sign In

a lil further on this, speaking to my buddy, trying to get a little more background on this.

last year that radiator was replaced due to a crack and leak.

car was running fine until about 2 months ago. started over heating.

he had the thermostat changed with no effect on the overheating issue.

so im leaning more heavily on maybe a head gasket or a water jacket crack somewhere internally in the engine?
__________________________________________________
2015 Jeep Grand Cherokee
2002 Ford Ranger
2004 Toyota Corolla
1969 Ford Mustang Mach 1


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 12, 2011, 4:53 AM

Post #6 of 6 (2429 views)
Re: jeep grand cherokee troublesome overheating Sign In

Hey DMAC - hear ya - tricky one. Still check that radiator doesn't have cold spot(s) newer or not. If you are getting combustion pressures into cooling system it could be the trouble. Pressure shouldn't build up too fast from cold as felt with just squeezing upper hose. Release any pressure (you know how to be careful) and see if it builds up again fast or faster than anything normal.

That would suggest head gasket.

Can you feel good heated air blowing off fan from radiator when fully warmed up?

T







 
 
 






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