over heating

Hi jeep lovers i am knew to the forum and i come with a problem i have an 88 jeep xj 4.0L and i just replaced the radiator and head gasket but it still over heats i am not loosing water nor oil but i did remove my thermostat could it be that there is to much water flow with out a thermostat.

the only thing i can think of that would cause your jeep to overheat WITHOUT a thermostat is that the water pump is bad, with everything working properly it would be impossible for your jeep to over heat because no thermostat is installed. take the radiator cap off, and without the thermostat installed watch the coolant inside the radiator when your jeep is running, it should be flowing and you should be able to see it moving, if you are not sure if the colant is moving, hock a big loogie into your radiator, then you should be able to tell :smokin:

New thermostat, check your mech fan clutch, and make sure you have a good 50/50 mix.

Never run the I6 without a thermostat - the computer does not like that and economy can greatly suffer as a result. Its better to find the overlying fault - in mine my radiator was nasty and I had blocked passages in my engine. Had to take the head off and thoruoughly flush out the block - now with a new 3 core radiator, a new high flow water pump, a heavy duty fan clutch and a 180 degree Robert Shaw thermostat I barely break 210 on hot days with my A/C running. Also if you run a 160 stat you run the risk of faster engine breakdown due to the fact that the oil now has to take the brunt of the heat.

Hi,

Sounds like you may have an air pocket in the cooling system. Instead of filling the system thru the overflow bottle, I always pull off the upper radiator hose and pour as much coolant as possible directly in to the radiator. Also, always run the heater after refilling the system, helps prevent air from being trapped in the heater core. :D

-Nick

Hi,

Sounds like you may have an air pocket in the cooling system. Instead of filling the system thru the overflow bottle, I always pull off the upper radiator hose and pour as much coolant as possible directly in to the radiator. Also, always run the heater after refilling the system, helps prevent air from being trapped in the heater core. :D

-Nick
Ya actually there is an air pocket in there or maybe it is creating one because whenever i stop and when it isn't over heating i can here air seaping out of the over flow bottle if the cap to the overflow bottle is bad and doesnt hold pressure to well will it create and air pocket.

Get rid of that air as soon as possible. Air in the cooling system is very bad! Especially if you have an aluminum block or head. Luckily Jeeps are iron but its still bad.

Get rid of that air as soon as possible. Air in the cooling system is very bad! Especially if you have an aluminum block or head. Luckily Jeeps are iron but its still bad.
is there a special way i can get rid of the air or is there a special way to fill it.

Here is a little trick for those with the closed system -

Jack up the back of the jeep a foot or so.

Take out the temp sending unit on the right rear of the block. If there is air in the system you will hear the whoosh as it escapes.

Add coolant till it runs out of the hole. Replace sending unit - make sure you use teflon tape on the threads.

That should do it!

Here is a little trick for those with the closed system -

Jack up the back of the jeep a foot or so.

Take out the temp sending unit on the right rear of the block. If there is air in the system you will hear the whoosh as it escapes.

Add coolant till it runs out of the hole. Replace sending unit - make sure you use teflon tape on the threads.

That should do it!

Thanks Po Pilot i have yet to do that but i will be sure to there is a knew thread on the subject is 90 jeep cherokee overheating i am have the same problem as him Is there any thing that could be creating the air pockets in my jeep would it be the head gasket or a warped block.

the only thing i can think of that would cause your jeep to overheat WITHOUT a thermostat is that the water pump is bad, with everything working properly it would be impossible for your jeep to over heat because no thermostat is installed. take the radiator cap off, and without the thermostat installed watch the coolant inside the radiator when your jeep is running, it should be flowing and you should be able to see it moving, if you are not sure if the colant is moving, hock a big loogie into your radiator, then you should be able to tell :smokin:


on 88 jeep cherokees there is no radiator cap (CAN'T STAND THAT) So do you think i could spit into the overflow bottle and it would do the same. And has anyone had any problems with a clogged heater core.

Zee, if you dont have the cap then you have the CLOSED system - one of the worse Jeep designs. Convert to the open system!

Here is a link to a great article discussing this:

http://www.olypen.com/craigh/rad.htm also: http://www.off-road.com/jeep/cherokee/98/12_dec/radiator/radiator.html

Comes with all the part numbers!


also check this one out:

http://home.earthlink.net/~jeepcherokee/Cooling/Electric%20Fan%20Control.htm


Hope this helps!

I've got an 84 Cherokee 2.8l V6, newly rebuilt motor, new water pump, new thermostat (2nd actually), new radiator that is overheating. It has no rhythm or reason, it maybe at idle, maybe as your driven, overheating (240+) then suddenly drops to 180. I keep the heater on since it keeps it from completely overheating (past 240), but very erratic.

Ideas?

Do you have the closed system? f so then burb the system.


Back up on an incline with the rear of the jeep higher then the front.

Undo the temp sensor on the back right corner of the engine block and then add coolant until it comes out of the sensor hole. Put the sensor back in and that should do it. Dont start the jeep with the sensor out or you will be covered in green!


If that doesnt help then I would look at your thermostat again. New ones are known to fail right out of the box.

I have an open system (radiator cap). Also on the V6 the temp sensor is on the driver side front of the engine, does this mean I should raise the front of the jeep?

This is actually the second thermostat and I have had a "qualified" mechanic (meaning not me) verify it was operational and installed correctly.

What about the clutch fan, if it fails can it create the symptoms I describe? If so I was thinking about trying an electric fan. Feedback on this idea would be appreciated.

Thanks for the help!

Well then if you have the open system then you dont have to worry about burping it.

Dont know if the clutch fan will cause that erractic behavior. Mostly at idle if the fan isnt working. Stick with the mechanical clutch fan - I have heard horror stories about converting.

Have you flushed it completely? Also - ever stop to think it might be the gauge itself? New Radiator cap?


Best thing to do is to run it up to operating temp and then see if you can get an infared temp reading off the radiator to see if it is close to the temp gauge!