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Unread 11-06-2012, 02:30 PM   #1
eripp1
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1996 FSJ Cherokee 
 
Join Date: Nov 2011
Location: Kennewick, WA
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Replace Water Pump+stat...still overheating! WHY!?

I just replaced the water pump and thermostat in my 96 cherokee yet it keeps overheating. It takes a while for it to get hot maybe 10 minutes, but if im on the highway no problems whatsoever. Im stumped please help!

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Unread 11-06-2012, 02:32 PM   #2
richsandwich
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Is the fan working? Did you bleed all the air out?
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Unread 11-06-2012, 02:47 PM   #3
SuperSam
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did you replace the radiator? Have you flushed the cooling system? If you have no problems at highway speeds, it's your fan clutch
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Unread 11-06-2012, 02:55 PM   #4
GetLifted
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Mechanical fan clutch
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Unread 11-06-2012, 05:49 PM   #5
CJ7-Tim
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2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
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Overheating cooling system

Overheating can be caused by anything that decreases the cooling system’s ability to absorb, transport, and dissipate heat, such as a low coolant level, loss of coolant (through internal or external leaks), poor heat conductivity inside the engine because of accumulated mineral deposits in the water jackets or radiator, a defective thermostat that doesn’t open, poor airflow through the radiator, a slipping fan clutch, an inoperative electric cooling fan, a collapsed lower radiator hose, an eroded or loose water pump impeller or even a defective radiator cap.

The cooling system is a group of related parts that depend on proper function from each of its component parts to keep the engine cool. Service the cooling system and replace any under-performing or suspected weak parts. Any component part of the cooling system that is not fully doing its job will stress the others and your cooling system will overheat. Temperature creep on the 4x4 trails, at idle, or in stop-n-go traffic points to a weak or failing mechanical fan clutch.
The most important maintenance item is to flush and refill the coolant periodically. Coolant should be replaced every 36,000 miles, or every two to three years. Anti-freeze has a number of additives that are designed to prevent corrosion in the cooling system, but they have a limited life span. The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core, causing the engine to eventually overheat.


-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix. With a neglected cooling system you may have to flush several times.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside. Clean or replace as needed.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap if your Jeep has one. An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak.
-Inspect/test or replace the mechanical fan clutch. A worn fan clutch will allow temperature creep at stoplights, in heavy traffic, and on the 4x4 trails. A fan clutch that “looks” OK is not the same as working OK.
-Inspect the electric cooling fan and the fan relay. Apply 12 volts and make sure the fan runs. Exchange the cooling fan relay with one of the others similar relays. Confirm that the e-fan starts when engine temps reach 215-218*. Repair or replace the fan or relay as needed.
-Inspect/test or replace the coolant temperature sensor that activates the e-fan.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.

If you have covered all the points listed above and still have overheating issues, inspect the head for cracks and head gasket for leaks. Exhaust gasses entering the coolant can raise the temperature of the coolant or cause steam pockets in the coolant that will temporarily block the flow of coolant

Read more about cooling systems here –

www.offroaders.com/tech/engine-overheating.htm

www.familycar.com/classroom/coolingsystem.htm
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Unread 11-06-2012, 05:53 PM   #6
tripped42
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i have put in a brand new thermostat and had it not work,, i have had dozens of people tell me never to trust a new thermostat,,, cj7 tim is the man, as always, but for inexpensive as it is,, buy another thermostat and try that
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Unread 11-07-2012, 07:59 AM   #7
OhioXJ2010
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All the advice above is super helpful as always!! If all that checks out ok, but you are still running hot, then consider installing hood vents. I did and it made a big difference for my XJ . Keep on it and you'll figure it out !!
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Unread 11-07-2012, 08:43 AM   #8
GetLifted
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The "runs fine on freeway but overheats at a stoplight" is almost always a mechanical fan clutch.

Easy way is to hot/cold test it, or just take off the shroud and see if the clutch looks wet and dirty (leaking). If its over 5-10 yrs old I'd replace it anyways. They cost like 40$. My 96 just got a new one 2 months back and it was the original I was replacing. I would run fine at speed but temp would creep up when at a stoplight.
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Unread 11-08-2012, 11:57 AM   #9
eripp1
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Thanks so much for all the advice! i will replace the fan clutch and see if that helps! as far as i know it is the original so i should replace it anyways
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