rivers 42

my 91 cherokee sport 4.0 new water pump new thermostat 195 degree and flushed why does it still reach the high red zone with the ac on only? fans work tried the birp method no radiator leaks its still high temp without a thermostat installed ? any clues please

SeriousOffroad

Are you 110% sure you got all the air out of the cooling system?

COSXJFAN

If your rad has never been gone through, I'd say that it's time. HTH!!

Abovetimberline

Is the airflow to the a/c cond restricted?

rivers 42

when i reverse flushed it there was a mud color coming out the radiator neck? as far as the Birp im assuming its correct i did it 10-12 times until i didnt see any bubleing? as far as restriction im not sure but i do need to replace the shroud i damaged it changing the thermal fan clutch my jeep only gets in the red with the ac on without it on its at the mark before red zone i do notice all the hoses severly hot except the 2 to the heater core? they are warm but not hot to touch but as soon as i touch the hoses after the heater control valve they darn near burn my fingers. Also after birping i do notice if i take the radiator cap off with a heavy towel to prevent danger to myself the coolant hesistates momentarily then it erupts out of the radiator neck like a volcanoe?

GreenGrenade32

Hate to tell u the news but its probably the radiator man. I got a 95 and it ran right around 210 untill the ac was on and it steadily climbed to red. Go ahead and swap it if u can. Ur gonna have to eventually

sportrider

I had the same problem replaced it with a $130.00 autozone Radiator and the problems fixed

rivers 42

Thanks i kinda had a 98 % feeling its the radiator i forgotr to mention the heater hoses that go into the heater core in and out dont seem to be that hot when the Jeep is super hot?

SeriousOffroad

Sure sounds like air in the system.

rivers 42

Air in the system seems to be sticking with me also after i changed the water pump and themostat i noticed it was still getting hot until i tried birping method that controlled the high red zone temp till i put the ac on ? Maybe im not correctly BIRPING THE SYSTEM THE CORRECT WAY? When i flushed it originally before the new Bosch water pump i installed i purchased a reverse flush kit and ther flush chemical and a bottle of vinegar i ran the engine till it was hot then flushed thru the heater hose Tee i installed it did have a lot of brownish color running out and i couldnt seethat before i flushed it 5 times ? the antifreeze always appeared green when i opened the radiator cap

SeriousOffroad

If you haven't done so already, re-install the t-stat but do this first.

Put the t-stat in boiling water till it opens up, then stick an asprin in the opening. You should also remove the heater hose from the t-stat housing while filling the system.

After the t-stat is installed the asprin will hold the stat open to allow for coolant to flow through it and fill the block. The asprin will desolve and allow t-stat to function normally.

huntingman2706217

ok he said he only gets in th red with the AC ON...which means when its off it doesnt overheat... which mean your compressor clutch is burning up or the bearings in the pully or the compressor its self... its overheating... locking up and causeing a larger load on your belt system and the motor causing the over heat when AC is on only...

If it doesnt over heat while it off then i would say the bearings in the pulleyand compressor are fine and its just the clutch thats freezing up... can be a cheaper fix...

rivers 42

Do i need to remove the entire compressor to replace that compressor clutch? i do notice the compressor diengaging at times is that normal

sportrider

I'd still go with the radiator, you have to consider when the AC is running the condenser gets hot, if you already have a compromised cooling system not only the extra drag from the AC system but the added heat from the condenser will have an effect on the limited cooling your radiator is already doing. as far as the AC compressor cycling, if you are low on R-134 it will kick the compressor off on the low side switch. I believe it's at around 20 psi. if the electric fan is functioning correctly the fan kicks on at around 275psi on the high side. if you see the fan kick on and around the same time it kicks off the compressor disengages odds are your low on gas.

as far as the clutch burning up, it's possible but unlikely. if your cooling system was operating at 100% and the AC compressor seized it wouldn't cause your engine to overheat, until it smoked the belt and your water pump and fan quit turning.

rivers 42

Sport Rider will the fan shroud make that much of a cooling difference? i broke mine changing the fan clutch or clutch fan ? also i noticed in 90 degree weather i sat with the cherokee running with the ac on at leat 20 minutes ? the over flow tank was full that day after it hit the 260 mark i checked the tank and it was empty? i never saw this jeep boil over i just see it stay in the red zone with the ac on? The cap on the radiator is never too hot to touch i wonder why? should i use the cap with red lever?