Cooling Problems2

See previous cooling problem thread dated 11/4/03

Anyone know how to "bleed" a 1991 Jeep Cherokee "Open" cooling system to remove the air out? I have read a few different ways to do it, wondering which is best........can't seem to get this thing fixed

I can't seem to get the fluid flowing through the upper radiator hose (it only trickles through). The temperature light comes on, the hoses and radiator is hot, but the cap is not hot (seems to be indicating a lack of flow in radiator). I have a new radiator, water pump looked to be in good condition and is only 1+ years old, new temperature sensor, and a new 180 thermostat. I have also flushed system twice. Any other suggestions would be greatly appreciated.

be carefull not to overheat the engine, the block and head have a tendency to crack.

Check the lower rad hose and see if it is kinked or coming apart inside, I have had that happen and took forever to figure out, because the outside looked good. If not that, then check to see if the water pump is flowing as you can do this with the upper rad hose off. Start the engine for a few seconds and see if it pushes water out the top thermostat housing, this is also one way to bleed the system.
Good luck

Thanks for the info, the lower hose looked fine, plus it has a metal "spring" inside to keep it from collapsing. I did pop off the upper hose and the water pump was pumping fluid out, but it seemed to be "pulsating" versus constant flow, and also it didn't seem to be very forceful. However, I had pulled the water pump off and it looked fine, impeller was tight, hasn't leaked, etc. I don't know what to try next?? OR if I should just spring for a new water pump.....trying to avoid spending anymore $$$

sounds like you have an obstruction somewhere. the only other thing I could possibly think of that would rob you of some of your flow, is if the heater valve is stuck open and a percentage of your coolent is just circulating through the heater-core and back to the water pump.

hoestly I doubt that could account for this much reduced flow but it could account for some.

I'm planning to switch my 89 over to an open system this spring. I'm serriously considering swapping out the mechanical fan for an electric that mounts directly to the back of the radiator (they have front mounting ones also but it looks like a real pain to try and get it in behind the grill.

my thought is that if I go with an electric fan I can re-route the upper hose so it goes more or less directly to the radiator. since I won't have to worry about getting it past the fan right after leaving the thermostat housing, I can avoid that whole air-trap made when the hose comes up off the engine, around the A/C pump and back down to the radiator.

when I get it done I'll let you know how it works out. so far temp is doing ok (actually running a bit cold), after a summer spent flushing it out and using cleaners in it about once a week for the last half the summer. I back flushed it, used prestone radiator solvents, syphoned water form the radiator (to get the debris from the bottom), put in a 180 fail-safe thermostat, cleaned up the contact on the 'coolent temp sensor'. and put additive in the coolant that is suposed to improve heat transfer from the engine to the coolent and from the coolent to the radiator (I had my doubts, as I don't put much faith in the 'mechanic in a bottle' products. but tried it and the jeep did seem to run noticably cooler than before).

I also burped out the excess air by removing the temp guage sensor while parked facing downhill. I have my doubts this would help you though as I'd thought that an open cooling sytem would solve the trapped air issue. I would have thought that with an open system you could get the car hot enough for the thermostat to open, then pop the cap off and rev the engine a bit pushing the air twards the radiator where it could escape, meanwhile you keep relacing the air with coolent unitl there is no room for air.

it sounds as if you've still got the radiator (and more importantly the cap) lower then the highspot in the upper hose. so that basicly if you did have it somehow burped you would loose coolent and replace it with air anytime you opened the radiator. (is this right?)

if so you will probably need to find away to re-route the hose so it climbs(one idea is the electric fan I mentioned, if someone has another idea that is better, cheaper, easier, or any combination of the three. I'd apreciate hearing about it before I charge ahead with my plan) more or less steadily to the radiator. without that I see no way to easily remove excess air if your cap and fill point are below the highest levels of your system.

I have an 89 cherokee limited and a about 70,000 it started running hot, over 220*. I replaced the fan clutch and had the radiator rodded out and with a new therostat, Then it would not even get to 195* in the Las Vegas summer with the A/C running. So most of the prolbems with over heating on these usually are a pluged radiator. Mine was a 4 core and more than 70% where plugged. And when filling I filled through the top radiator hose till it came out of the thermostat housing then hooked the hose backup and finished filling the reserve tank and check it after it warmed up.
Good Luck