Over Heating

I have a 1988 Jeep Cherokee (4.0 straight 6), recently ive had problems with boilovers so i decided to take out the thermostat, the engine ran fine ruynning cool and everything, but about a week ago, the engine started over heating severly, i finally took a look at it today when i had time and noticed that a there seemed to be no circulation of the coolant since the over flow tank was not letting any of the liquid back into the system (it was empty since everything spewed out when it over heated, so i removed one of the hoses that goes to the engine to see if there was any liquid in it just to see if the water was circulating and it was completely dry, a freind told me to flush the coolant system, but i kinda figured that that is stupid sice the stuff is not circulating anyways, and then he said that maybe my water pump is out since there is no circulation of the coolant...i need help as quickly as possible, and also is it hard to put in a new water pump?

thanks to any help

Taking out the thermostat and running without one is not a cure for any overheating problem.

The thermostat is necessary to ensure proper coolant circulation to the back of the block in almost every engine, especially the 4.0.

The cherokee's have a heating problem with the closed cooling system they came with.

I've seen web pages describing very successful conversions of the cherokee cooling systems to an open style and ending the overheating.

I'll see if I can find the link for you.

Meantime - Get a 180 t-stat minimum in there. fill it with coolant and bleed the air out of it. That's the trick - to get all the air out.

JD

Here they are!!!!!

http://www.off-road.com/jeep/cherokee/98/12_dec/radiator/radiator.html

http://www.off-road.com/jeep/cherokee/98/06_jun/cooling/cooling1.html

JD

EDIT Here is another

http://jeepsunlimited.com/xj/cooling/cool.htm

Thank you very much for the help, the "burping" seemed to work well, and the car is running pretty well now...thank you

i just got back from driving the car...and when i parked i noticed that there was some dripping going on...not alot..it could be condensation, but it had a greenish tint to it...should i be worried?

worried? no. Concerned? yes. It could be leftover from your overheating or it could be dripping from any of the hoses or the waterpump. Let it cool down and dry off then open the hood and dry everything off and wipe everything clean for the colling system then run it at idle until it warms up to operating temperature and check under the hood for leaks. If you have overheated the engine a couple of times it could be anything from a leak around a hose clamp to the water pump seaping (which is a sign it is about to go), to the radiator leaking where the fins meet the end tanks. Don't fret though as the whole cooling system is pretty easy to fix/replace and in your case with the closed system you have the opportunity to move to the open system if you have to start pulling and replacing things. Easy stuff to fix, just remember to take your time and everything will be cool :-)

For all of you that have a pre 1992 Jeep Cherokee with 4.0 Ltr 6cyl engine. I have the solution to your cooling system wows. My Jeep Cherokee is a 1988.
The stock Pre 92 system is a closed system with no radiator cap and complicated plumbing for the heater core and the coolant expansion tank.
The problem with the system, as I'm sure your already aware.
1. The coolant expands and blows out of the expansion tank cap with no place for it to recover from.

2. The electric coolant fan switch is in a bad location and rarely turns on the fan when needed because of constant coolant loss leaving the sender un-exposed to coolant, and its location in the radiator is a cold spot because of the design of the radiator.

Remove the original radiator and replace it with a Modine NAPA # 2802 or equivalent. This radiator is listed for a 1992 Jeep Cherokee. This radiator is an open system exact fit and has a radiator cap/fill neck. All hoses and transmission lines will connect in the same place. This radiator does not have a provision for the fan switch (I will get to this).
The proper radiator cap for this unit is NAPA #705-1445

Remove the water outlet (thermostat housing) and replace it with the housing from a 1993 4.0 6 cyl Cherokee. This is a dealer or auto recyceler item. This housing is an exact fit with all of the hose positions in the same place. In addition this housing has a hole tapped into it for the 1993 temp gage sending unit. This is were you will mount a Fan switch to replace the one that was on the origional radiator. This new switch location has better heat transfer to the switch so the electric fan will cycle more frequently thus resluting in better cooling.
Since you have the housing off this is a good time to replace the thermostat.

You will need a Fan switch. I used NAPA # FS113, and the proper connecter to this switch is NAPA # FSC10. This will turn on the fan between 207-220 degrees. The origional radiator mounted switch activated at 230 degrees. As mentioned earlyer the new fan switch mounts in the 1993 thermostat housing.
The switch is a single pole switch with one wire and switches to ground so you will have to use a head light/horn relay to connect it to your original fan wires.

1. Run the new fan switch wire to the ground terminal of the relay.

2. Carfully cut off the original wires with plug from the original radiator mounted fan switch. Cut them off at the switch side so you have the plug with the wires attached. The yellow wire is +12V and the black wire goes to the original fan relay. Connect the wires with plug to the switched (load = yellow, output= black) terminals of the relay. Since the yellow wire is hot +12v when the ignition is on use this wire (make a jumper to connect to the + side of the relay) to power (activate) the relay.

Recap step 2. Yellow wire goes to relay + (positive) and relay load terminals. Black wire goes to relay output terminal. Fan switch goes to relay - (minus /ground) terminal.

3. Remove all heater hoses, coolant expansion tank and mount, metal y-pipes, and heater valve if your model has one. Be carfull not to break the plastic vacume line attached to the heater valve as it can become brittle.

4. Install heater valve NAPA #660-1174. This valve has 4 connections. Looking at the valve from the opposite side from the vacume switch with the curved end of the valve facing upward you will see one connection facing forward, two connections facing back and one facing at a 45 degree angle facing towards you. On the bottom angled connection run a 5/8" heater hose to the thermostat housing. On the single connection on the front run 5/8" heater hose to the water pump. Connect the two rear facing connections to the top and bottom connections of the heater core. Connect the vacume line that was connected to your old valve to the connection on the new one.

5. Purchase an after market coolant recovery tank and mount it in the hole were the old coolant expansion tank/mount was removed from.

6. Run a 5/16 fuel line or equivalant from the expansion tank to the fitting just below the radiator cap.

7. Fill cooling system using standard methods and precautions.
Parts list. I used NAPA auto parts as a source so all part numbers are NAPA numbers. These are standard replacement parts and can be purchased from any after market or dealer source.

1. Modine Radiator # 2802 for 1992 Jeep Cherokee.

2. Radiator cap #705-1445.

3. Coolant Fan Switch # FS113.

4. Fan Temp Switch Connector # FSC10.

5. Heater Valve # 660-1174

6. Water outlet from 1993 Jeep Cherokee (dealer only or auto recycler).

7. Standard 30amp Headlight/Horn Relay.

8. 8' 5/8" Heater Hose.

9. 10' 5/16 Fuel line.

10. Teflon tape or equivalant thread sealant for Fan switch threads.

11. Small roll of 12 gage wire.

12. Small package of 1/4" spade connecters to connect wires to relay terminals.

13. Small package of butt connectors to connect fan switch to wire going to relay.

14. Two gallons of Antifreeze/Coolant.

You will now have a standard open cooling system like every other car on the road. No more will you be stuck on the side of the road with an over-heated Jeep as the result of running out of coolant because of the Renult designed closed cooling system. When you add coolant to the new system you will know that your radiator is full because you fill the radiator now, and you now have an overflow tank that will return the expanded coolant into the radiator when it cools down (just like every other car on the road.

This conversion takes about three or four hours depending on your abilitys. Show this list to any radiator shop and they will know what to do if your not a do-it-yourselfer.

The bottom line....This conversion will cost you about $350 to $400, about the same as replacing the origional components, but with the benifit of no more problems and the insurance of not overheating and causing expensive engine damage.
Happy Jeepin'