Mechanics

MODELS OVERHEATING

2000 Jeep Other

Engine Cooling problem
2000 Other Jeep Models 6 cyl Four Wheel Drive Automatic 102000 miles

Had local shop replace electric cooling fan, only one fan, they installed it backwards (blowing towards the front of the car) and wired backwards, a torqflo, did NOT fix the overheating. I replaced the ac clutch relay, the water pump, the surpentine belt(dry rot), thermostat and gasket, blew out the radiator 3 times garden hose, no heat, blew out the heater core with garden hose got lots of rust filings, 3 times, got heat back. Runs fine all day until we get into stop and go traffic about a 2 mile stretch! It overheats. NO codes come up. I checked the transmission fluid while it was running and found bubbles, not sure when that had been serviced, red in color. Could old tramission fluid cause a vehicle to heat up in stop and go traffic? I'm thinking of replacing the radiator or adding a tranny cooler.
We go up the beach every sunday during the summer since we have owned the car never had this problem approx. 10 miles of driving.
If you can think of something I missed please let me know. (Carpenter by trade, but I fix my own vehicles, mechanics over$100 an hour!) I fixed it last time, it was a bad fan relay! Located behind the passenger headlight!
Thanks in advance, Lee
Avatar
Lee1961
July 13, 2010.




Well next time vehicle over heats pull over to the side and quickly take a sheet of paper and stick on on the radiator towards front of vehicle. Does paper stick or flake off? Is fan running? This will tell us if you got good airflow and then we can start going further into depth. Good luck!

Blackop555
Jul 13, 2010.
It overheated and the paper stuck just fine to the front of the car. So the electric fan is pulling air through both the radiator and the transmission cooler.
The car does have transmission cooler. I guess the question is once again would old or worn out transmission fluid cause the overheating in stop & go traffic? Can an air test be done to a transmission line and cooler? To see if it is blocked or leaking. According to the manual trans fluid should be changed about every 12000 miles. I cannot find out when it was done last.
I looked up the specs on the waterpump for this jeep and on one website said it was " standard rotation" and another said " reverse rotation" the manual for 4.0 said look for the " R" stamped on the impellor, no " R" on the old pump or the replacement pump. Who is correct? Thanks Lee

Tiny
Lee1961
Jul 14, 2010.
They should be marked buy they may not be. Jeep belts can be put on wrong way causing pump to turn the wrong way. If you ordered it right it should be correct. But if pump was bad vehicle should be overheating all of the time just not at idle.

Now might be a good time to have the engine block back flushed you can try to do this by a garden hose if you want.

Trans fluid wouldnt cause that high of an overheating no wear near noticeable really unless your fluid was burn black meaning extreme quantities of heat. If the torque convertor was locking up it could cause that but you would feel a big strain with foot on the brake while idling and the engine would want to die out.

When vehicle overheats does brining the rpms up cause the temp to drop?

Blackop555
Jul 14, 2010.
Ok here is the latest. I flushed the engine block and a small amount of debris came out. After wards the fan seemed to do its job better.
When it overheats running the RPMS up does nothing.

But the connection I have now is this: When I run the car in stop and go traffic with the AC ON it heats right up, If I turn the AC OFF it cools right down. If I run the car at a higher speed 35mph and no stop and go traffic with the AC ON the car runs fine.(Ram air) I have checked the fan to see if it is running when it over heats and it is running. A real test would be beach driving without the AC ON.
What do you think is the connection with the AC?
Is the AC coolant a player? Not enough, too much?
I had a buddy check the codes and nothing came up.
I'm getting closer to the fix.
Thanks Lee

Tiny
Lee1961
Jul 20, 2010.
Ac coolant wont do it but when the pump is running it really bogs down an engine and causes excess heat. Thats why you have the mechanical fan thats always on and a electrical fan that turns on when ac is on. With that sheet of paper that I previously mentioned does it stick all over the radiator or is there parts that seem weaker?

Blackop555
Jul 20, 2010.
The paper test works uniformly over the entire front of the car.
Is there supposed to be a recommended amount of space between the radiator and transmission cooler?
I was thinking of blowing out the fins of both the radiator and cooler to makes sure there is no debris to block the air through the units.

This car has never had a mechanical fan ONLY the electrical fan.

Thanks Lee

Tiny
Lee1961
Jul 21, 2010.
As long as the mounts arnt bent then it should be the proper distance. There is no really set gap to check on the fan from radiator clearance.

So both fans appear to be operating normally.

Do you have access to a scan tool that can read components on the vehicle such as the AC command and fuel trims? This way we can see if the ac command is being processed and actuated through the computer.
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Blackop555
Jul 21, 2010.
There is only one electrical fan, no mechanical fan. Maybe you are referring to the(second) fan that pushes the hot and the cold air in the car's interior?
I did have a friend with a car diagnostic computer check for codes. There were none. (A handheld unit)
There has to be a build up of heat only when the AC is used. So what occurs when the AC is turned on? It drags on the engine; but how?
Does the AC have anything to with or any connection with the radiator or trans cooler? Are there lines from the AC that need to be cooled not with the fan?
I'd like to see the schematic of the jeep AC layout and the transmission layout with the cooler. Is there anywhere online I could view this layout. Can the AC system be blocked like the radiator?
I know alot of people are probably having the same problems as I am. It truly seems odd that I have used this vehicle on the beach with the AC on for many summers with none the these problems.
Like I said experience is everything alot of which CANNOT be learned in a book!
Thanks again Lee

Tiny
Lee1961
Jul 21, 2010.
Ac system when turned on engine is loaded down and vehicle turns up the idle by allowing more air in to the vehicle if o2 sensors dont catch this vehicle can run lean at idle but it should clear up when you start moving again. I can get you a picture of ac system and trans but it wont tell you how its routed in ac. Ac system cools before the radiator and radiator and trans comes next.

It drags engine down when it activates as it requires power to turn it. Just like an alternator. With that energized with 12v you cant turn it by hand.

Is your ac inop? Warm I mean

Blackop555
Jul 22, 2010.
I knew that running the AC loads down the engine. So not running it puts less stress on the engine.
I'm not sure if schematics would help either.
But here is what I did yesterday. I took the car on the beach, soft sand, at 15-20mph, AC OFF. The temp stayed 210 and below all the way to Great Point! Until I
backed up the beach about 200 feet the temp then went to the first line past 210! I opened the hood fan still running! I left it running with the fan running and it cooled down in 10 min. When I drove it home later in the day it stayed at 210 and under.
Is there anything that happens different to the engine when backing up then going forward? Something with the exhaust, catalytic converter, transmission?
Well it was a good day anyway 12 bluefish landed without the seals stealing any!
By the way the radiator hoses were both hot!
Thanks Lee

Tiny
Lee1961
Jul 26, 2010.

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