Coolant system help please!! -
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Unread 09-07-2011, 01:56 AM   #1
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Location: miami, fl
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Coolant system help please!!

Hey guys, first time jeep owner here.

2000 cherokee sport 4.0 6cyl

I bought this jeep 3 weeks ago, and Im having cooling problems and my car overheated the other day.

The car ran way under 210 when i bought her(first day). Then i changed the oil next day after purchase and noticed the car started to run up towards 210.

Week later i flushed the radiator system entirely (noticed rust build up inside), new 50/50 and water, new upper radiator hose and lower radiator hose, i also changed the spark plugs (bosch platinums) in the hopes to increase gas milage.

Then i started noticing the car regularly running at 210 and it starting climbing to 225. Kept driving ok, then 3 days ago while in traffic she went right from 225 and jumped to 260. Lights and buzzers were going and i managed to pull into a parking garage. Popped the hood and coolant resivior was bubbling hot!

I let the car sit till cold (5hrs), then popped the radiator cap and ran her in the hopes to burp the line incase it was an air bubble. I noticed the coolant wasnt flowing into the radiator but overflowing out of the open cap. The system seemed backed up.

Today i changed the water pump (mild-med corrosion) and i changed my thermostat (only to find the car didnt have one.) New water pump and gaskets, new t-stat and gaskets, but car doesnt seem to be cooling.

I also noticed today, that the previous owner disconnected the 2 hoses that go to the heater coil and connected them with what looks like a v- shaped joint (which i guess explains why i have no hot air.)

Any thoughts or help??

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Unread 09-07-2011, 09:42 AM   #2
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2000 XJ Cherokee 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 24,076
210* is the normal operating temperature. The 200-01 Cherokee 4.0 L does not run well on Bosch or any other Platinum type sparks plugs. Use AutoLite APP-985 with the distributor-less ignition.

Assume that the Previous Owner neglected the cooling system ( rust, water pump, heater core issues, ) and that possibly everything needs to be replaced.

Google Jeep 0331 Head and find out why you may need to replace everything. You should inspect the head for cracks and perform a simple compression test.

Overheating cooling system

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. The most important maintenance item is to flush and refill the coolant periodically. 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. Coolant should be replaced every 36,000 miles or every three years.

-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 –

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Unread 09-09-2011, 03:15 PM   #3
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Location: miami, fl
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awesome, thanks!
Jeepdave110 is offline   Reply With Quote Quick reply to this message

cherokee , cooling issue , help needed , over heat , over heating

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