89 jeep cherokee 4.0 4x4. I just replaced the raidator (sp) and the thermo. The jeep will not stay cool. The thermo in cab will peg 260 in about 10 minutes. I dont know where to go from here. I was tuhinking water pump but therre is no play in the shaft and the thing seems to be woprking still. Any idea where tio go? Thanx...


Mike

may not apply but... on the 4.2l (258) the cooling system is suseptable to air locks that cause overheat issues. Best way around is to drain system, pour in 1 gallon of coolant mix, warm engine with heater turned on, finnish filling the sytem with engine warm and running. this usually gets the air out of the system and allows the vehicle to run at the correct temp.

Other than that, could be anything from timing to a clogged exhaust pipe. :grinpimp:
Good luck,

Try posting at www.naxja.org in the stock area. You'll probably do better on replies. They have a lot more experience with this kind of problem. :cool2:

I would agree that you have air in the system.

I agree with air lock. Easiest way to do an XJ, without the engine running, is to remove the small heater hose from the thermostat housing. Fill at the overflow tank. When fluid comes out of the thermostat housing, the system is full and should be free of air.


Erik

overheating checklist:
1) lower radiator hose - does it have the spring inside it to prevent collapse?
2) air is burped from system - on 87-90 XJ models the best way to do this is to pull the temp sender which is located on the rear drivers side of the block, right next to the valve cover, while the jeep is parked pointed slightly down hill,
3) correct thermostat - go to the dealer for this, they have the correct gasket with them
4) pressure bottle cap - replace with new

I will think of some more or go over to NAXJA like they said before and search over there.

I know this thread is old but I just fixed a the identical problem. Cut the return line in the rad hose. Order summit part SME-2202 inline filler neck. Plug both lines to the expansion tank-plumbed off your heater hoses. Add a generic overflow bottle and rad cap. Now you have an open system. In addition-drill a 1/16" hole in your thermostat to self burp the system. If you still have overheating problems-its not due to air-your radiator is junk or a head problem.

Some people do the full radiator dwap-to a newer cherokee-but this does the same. think-less $$$ less labor.

The plastic overflow/fill bottle cracks easily. Check to see it isn't leaking and the cap is nice and tight. When does it get hot, at idle or at speed, or both? Also check on NAXJA for more info.

Troy