After I noticed oil seeping from a tight, new ccv valve and a few over heating issues, I decided to investigate. Here is what I found...

1. I put in a junkyard electric fan (six months ago), noticing the connections were hardwired. I undid the hard wire, used standard connections.

2. Fan will turn on when engine gets to temp only when defrost, bi level, air or max is on, not the vent or heat settings.

3. At idol, Cherokee overheats, found it would not overheat if electric fan is on (it will not cut on unless bi level, defrost, air or max temp setting is on. will not come on if no air setting is selected.)

4. Checked air filter. It is half covered with oil/water mix. Light Brown Sludge.

5. Checked dip stick. No sludge or water.

So how did the vacuum become reversed in the air housing? Any help? I think the fan was hooked to a toggle to by pass a thermo switch that is bad??

 

did you pull the radiator cap off and look for that brown sludge?

 

change thermostat. Had problem like this on one of my old cars.

 

there is no radiator cap, but i guess i can take a hose off and check it

 

thanks for thermostat, ill look into that for sure

 

the hose will work forgot about the cap havnt had a jeep in a while

 

I am assuming this is the 1989 in your signature.

So the radiator does not have a cap. It is on a pressurized bottle. Correct?

If so, you have the old style cooling system, which I personally have found to be a nightmare.

I would start by replacing the radiator from a newer cherokee. You will also need to swap the t-stat housing from the newer cherokee, so you can get the new coolent temp switch in the t-stat housing. There are a few write ups on this you can find with a search, But either way, If you like your jeep and want to keep it. Start here. Do a new t-stat while you are in there.

Just my opinion.

As far as heat goes, pull off your heater hoses and check the flow, you may need to flush the heater core.

"1. I put in a junkyard electric fan (six months ago), noticing the connections were hardwired. I undid the hard wire, used standard connections."

Should not make a differance, as long as connections dont corrode.

"2. Fan will turn on when engine gets to temp only when defrost, bi level, air or max is on, not the vent or heat settings."

Verry strange, Think I would brake out the chiltons. and test for power at the fan relay. May be a issue with the sensor. On some grand cherokees the fan goes on at lower temp depending on hvac controls.

"3. At idol, Cherokee overheats, found it would not overheat if electric fan is on (it will not cut on unless bi level, defrost, air or max temp setting is on. will not come on if no air setting is selected.)"

Sounds like an issue with the cooling fan electrical circut.

"4. Checked air filter. It is half covered with oil/water mix. Light Brown Sludge."

Fairly normal for a jeep with high miles. You can inspect the pcv system for blocked vent lines. But I wouldnt worry about it too much.

"5. Checked dip stick. No sludge or water."
If it also has no sludge under the oil cap, or oil in the coolent I would say this is a promising sighn.

"So how did the vacuum become reversed in the air housing? Any help? I think the fan was hooked to a toggle to by pass a thermo switch that is bad??"

Yes, that is bad. The thermo switch is there for a reason.

 

I got an in line rad cap for my 89. I had put a new three core rad in not that long ago and did not know about the up grade to a newer year. I read another post on here and found out about the in line cap. Took the old bottle out and used it as a target for the shot gun! That was the best feeling int he world....what a pain it had been for the past 6 years. The new cap works great and I have drained the system two different times...two different leak repairs. I have another 89 in storage and you can bet that it will be up graded with an in line cap because it also has a new rad in it as well.

Here is the link for the rad in line filler system. http://www.summitracing.com/parts/CSI-971/ Only other issue is you must change the plastic bottle to an over flow system and the heat valve needs to be changed as well. I think the over flow and heat value cost about $30.