First off, Yes, I searched for the past two weeks.

My 89 4.0L XJ, converted to open cooling system, is overheating when going up hills or when load is applied.....It boils over at red line, so I know its really overheating. Does not overheat in town or at idle.

I have done/replaced-
-Fan clutch
-Water pump
-Thermostat(3 times, all different temps and manufaturers, and even tried no t-stat.)
-New radiator(had a griffin)
-Installed dual elec fans
-washed out AC condensor fins
-Burped it countless times
-flushed coolant 4 times....Always comes out looking brand new.
-Combustion gas leak test....Came back negative for exhaust gases in my coolant.

Im at a loss on what it could be, other than clogged coolant ports in the head. It reaches 260* at the back of the engine, while the rad and hoses stay around 170-180*(verified with tinfared temp guage.)

Engine doesnt seem to be running lean...but I could be wrong. Check engine light doesnt work, so I cant flash codes.

Anyone have any ideas for me before I go replacing this engine???

 

Renix doesnt flash codes, so thats that...

Seems like poor flow, would the waterpump somehow be causing it?

 

Hum, a stumper here. I kinda suspect the efan set-up. Coolant temp will almost always increase somewhat, if not a lot, when going uphill due the extra load on the motor but normally shouldn't overheat. When u say going uphill, can u give some more details? Are we talking extreme grade/slope, for extended period of time, at what speed, with tall tires? Again, I suspect the efans not moving enough air under load.

 

I havent owned a Renix XJ in about 8 years. I have been spoiled with OBD I and OBD II xjs for a while....haha. thanks for clearing that thought from my head!

Put in a new water pump already, and made sure it had an "R" stamped on it, indicating it is the correct direction of flow.


I have literally replaced the entire cooling system...some components more than once just to ensure they were not faulty from the box.

I also checked the O2 and it is working correctly. I checked timng, and its at 12 deg adv timing. I dont know where an xj is supposed to be, as I have never checked before. I know they are not adjustable and the PCM controls ign advance or retarding.

Does anyone know what the timing should be on an 89 XJ so I can rule out a faulty sensor causing it to run lean???

 

I am having the same issues with my 92. If you figure this out please let me know. I will be following this thread!
Good Luck

 

Do u have a different from OE stock rad fan set-up as well?

 

If you are asking me I have installed a 3 row CSF radiator and a hessco high flow water pump but I have stock fans.

 

what was done for heater hose lines and over flo bottle setup

 

Devil's in the details......tall tires, good air thru grille area, fan shrouds intact/in place, new fan clutch, extreme slope/grade, high ambient temps???? Again, give more details......makes the guessing a little easier. All motors run hotter uphill but shouldn't overheat 99% of the time.

 

How about checking the belt tension or maybe you don't have enough coolant in it.
You have to have a little more than 3 gallons to fill it up.

If you hear different noises at the engine after you shut it off then you don't have enough coolant.

I filled my system full and there was no noise after shutting the engine off.

Little ticks and tacs after the engine is off means low coolant.

 

Heater hoses go from the t-stat housing to the heater core inlet, then out the outlet to the water pump. Just how they are ran in 91+. overflow bottle is from a 96 xj.

Entire cooling system now mimics a 91+.

 

Mine is up a slight hill. Dont know if it does it when its cooler than 95* out because I have only had it for a couple weeks.


Belt tension is fine, and I def have enough coolant. I have emptied and refilled at least 5 times with new coolant everytime. Its been burped countless times. I dont know how there could still be air in the system. Coolant comes out right when I remove the rear temp sender on the head....no air. This is the highest point of my cooling system.




It really seems like an internal flow issue to me. I noticed yesterday, if I rev the engine, the heat gets hotter with rpm.

Got my donor engine pulled from my wrecked 98 xj last night.......going in next weekend if I cant get this figured out!...along with the pcm, harnness, and dash....has 100k less miles and OBDII. Glad I have my DD VW!

 

Isn't the rear of the motor lower than the front? I'm still thinking the aftermarket efans aren't cutting it.

 

have you tried running a cleaner through the system? how do the hoses look? are they soft causing them to collapse? what brand water pump? what size radiator? i know you said new fan clutch but does it have tension to it? fan shroud? heater core clogged? using any coolant?

 

Went right over my head........are we saying we have dual electric rad fans AND a belt driven fan???????