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Overheated yesterday. need help today

nated0g

NAXJA Forum User
Location
Memphis TN
I was going to visit my cousin in the new toy the xj. was driving along and all the the sudden i notice my thermostat was at 260. i just happened to be in front of a napa so i stop and play dumb. apparently they play dumb better than me. so i let it cool off and decide to drive it to my aunts house which is about 5 miles from where it overheated at. i have to stop every couple lights and let it cool off . i check the oil each time and its fine no water in oil. but smoke is coming out of the fill hole white. i get it there and call my cousin and he says that he can get it towed to my house and to change out the thermostat. i do that this morning and a note that i bought it as is and it had no thermostat installed. so i put one in and coolant in the fill bottle and cut heat on. within 5 minutes its at 240!!. and smoke is coming out of the dipstick white in color. what could it be? my valve cover is leaking but i did notice it was smoking by the oil filter seems to be a filter or something on top of that. i dont think its the oil pump since as far as i know they are inside the oil pan. could it be a bad waterpump not pumping? i notice the hose didnt get full like it does on my ranger but this is a totally different design with the closed system. oil pump? head gasket?
question about the head gasket tho if it was warped or cracked wouldnt that be the case with the water in the oil?

any help would be apperciated since i bought it in may and have maybe 200 miles on it.
 
forgot to mention what kind it is since ihave not set up my sig yet

89 cherokee laredo
4.0L Auto 231
4.5 inch suspension
32 inch BFG MT's
 
When the engine overheats, the first question to ask yourself is are you losing coolant? If yes, is there an external leak? If yes, fix it (replace broken hose, leaking water pump, leaking freeze plug). If no, there's an internal leak either through head gasket, cracked head, cracked block, or through corroded radiator into tranny cooler. Since the engine oil doesn't look like chocolate milkshake, check if there's water in the tranny fluid.

If the engine isn't losing coolant, does it overheat only in slow traffic, only at speed, or both?
The causes for each are different so if you can tell us which one applies to you, we'll narrow down the list of possible diagnoses.
The smoking from the valve cover could just simply be oil vapour because the oil's overheating.
 
I had a similar problem but my fan belt broke and the engne over heated on my 88 XJ. Do you put coolant in the bottle on the firewall or do you have a normal radiator cap. I'll assume you have the stock configuration with the pressure bottle on the firewall.

The plastic pressure bottle is known as the weak link in the system. People lean on it when doing service and put micro cracks in it. Also the "radiator cap" may not hold pressure and the engine may over heat. You can buy a new bottle from quadratec.com for $20 or something close to $50 at the dealer.

Also when you over heat you should replace the thermostat and the "radiator cap". They both can be damaged by the heat. My st louis radiator shop told me if the engine gets to 225F one time you can do perminate damage to the thermostat. You should buy the therostat at the dealer, it has a vent hole, posts on here say the aftermarket ones do not. Also the "radiator cap" used on that plastic pressure bottle can only be purchased at the dealer.

Also with the age of your XJ you may still have the factory fan clutch and the factory radiator. You could have a radiator which is clogged and heat can not be "rejected". Also if the fan clutch does not work then when you idle there is no air being pulled through the radiator.

There is a chance the impeller of the water pump came off the shaft but the is doubtful.

You did not give an indication of how long you owned the XJ, or what condition your cooling system is in. It might be time to do a cooling system renewal - radiator, hoses, pressure bottle, heater hoses, fan clutch. If you get to this stage buy all the hoses at the dealer, the fan clutch at a good parts store, the radiator from a good shop and the pressure bottle from quadratec.
 
I bought the jeep in may. it has had 2 owners one from 89-2000 and another one from 2000 til i bought it. I have tons of reciepts from the original owner including the bill of sale. the kid that i bought it from in 2000 put a lift kit on it and big tires and such. I dont think he took very good care of it. that being said.
I think that my issue is with the water pump since it was not cycling fluid from the fill bottle. but i did have the cap off that might have caused it. i dont know the condition of any of the cooling system since its a closed system. i will check the tranny fluid tomorrow. being unfamiliar with the aw4 tranny does it have a hot and cold level to check it. I might have a guy come and look at it. maybe do a compression check.
 
nated0g said:
I bought the jeep in may. it has had 2 owners one from 89-2000 and another one from 2000 til i bought it. I have tons of reciepts from the original owner including the bill of sale. the kid that i bought it from in 2000 put a lift kit on it and big tires and such. I dont think he took very good care of it. that being said.
I think that my issue is with the water pump since it was not cycling fluid from the fill bottle. but i did have the cap off that might have caused it. i dont know the condition of any of the cooling system since its a closed system. i will check the tranny fluid tomorrow. being unfamiliar with the aw4 tranny does it have a hot and cold level to check it. I might have a guy come and look at it. maybe do a compression check.

I am the GURU of overheating problems. CHANGE THE RADIATOR!!!. I bought a 4 core rad from Autozone for $130 and it went in just find and solved all my problems. While you're at it replace the water pump and t-stat (OEM) and the upper and lower hoses. make sure that you get the OEM lower hose cause it has a spring in it. I am the single most least mechanically inclined person on the planet let alone the forum and i replaced all of the above in a day. I had the same symptoms as you and now i can't get the thing to overheat even if i wanted to. The problem is most likely the radiator but since you have to take it out, you may as well do all that other stuff at the same time.

I think the total for the project was right around $200 bucks

Oh, and replace the fan clutch too if it needs it
 
Make sure the pressure bottle at the fire wall has the right amount of coolant in it. When you look in the hole you will see what looks likes a chair. Make sure when the engine is cool and fill the bottle until the level is over the round part and below the top of the piece sticking up.

Then run your vehicle, you should see coolant flowing through the upper hose and into the reservoir. If it now flowing then I'd have to agree with you the pump is in need of replacement.

Changing the water pump is not bad and it will give you a chance to do a lot of maintenance while you are there. You will have to remove the electric fan, mechanical fan, fan belt and return for the heater core and lower radiator hose to change the water pump. Take a look at the wye fittings in the heater hose circuit have the aluminum bands then they are factory, you should change them. Also my guess unless all those records say otherwise you have the stock radiator. I installed a new Modine 2 row radiator in my 88 XJ 6 months ago.

I could spend all your money but there a lot of things you can do "while you are at it". Fan belt, idle pulley, mechanical fan clutch, upper radiator hose, lower radaitor hose, all 6 sections of heater hose, the pressure bottle with a new cap, new coolant mixed with distilled water. Also a Mopar 195F thermostat it comes with a good gasket, I also like the dealer water pump gasket. Dealer water pump and thermostat gasket come with RTV preapplied.

When you disassemble get out some zip lock bags and put the bolts from each phase in a bag. This will help reassembly.

One more thing you will have the power steering pump removed, you will find it easy to change hoses. I have done everything I have suggested and it will improve the reliablity of the XJ.

Just ask I have tips for everything since I have done it already... lol

PS there is no good test for a fan clutch, if it over 5 years old change it. If you see a white 89XXXXXXXX part number on the AC Delco fan clutch it is factory.
 
nated0g said:
I bought the jeep in may. it has had 2 owners one from 89-2000 and another one from 2000 til i bought it. I have tons of reciepts from the original owner including the bill of sale. the kid that i bought it from in 2000 put a lift kit on it and big tires and such. I dont think he took very good care of it. that being said.
I think that my issue is with the water pump since it was not cycling fluid from the fill bottle. but i did have the cap off that might have caused it. i dont know the condition of any of the cooling system since its a closed system. i will check the tranny fluid tomorrow. being unfamiliar with the aw4 tranny does it have a hot and cold level to check it. I might have a guy come and look at it. maybe do a compression check.

Once again I'll come back to the same questions:
If the engine isn't losing coolant, does it overheat only in slow traffic, only at speed, or both?
Tell us which one applies to you so that you don't go spending lots of money buying parts that you may not need.
 
Dr. Dyno said:
Once again I'll come back to the same questions:
If the engine isn't losing coolant, does it overheat only in slow traffic, only at speed, or both?
Tell us which one applies to you so that you don't go spending lots of money buying parts that you may not need.

It has just overheated 1 time and that is when it almost left me stranded. No coolant lose anywhere in the sytem other than the boilover.

I am thinking its the waterpump due to when it was running after the themostat was changed i could not feel or see any coolant going down or feel it in the hose. Might try the open system trick like i have seen on many postings.
 
If the water pump is failing, it won't be circulating enough coolant and the upper radiator hose will feel soft all the time. Make sure that the serpentine drive belt is at the correct tension and that it isn't slipping on the water pump pulley. While you're there, grab the pulley with your hand (ignition and engine off, of course!) and see if it wobbles. If it does, the water pump is toast.
Since you have the closed system, you might wanna change the pressure cap on the bottle and check the bottle itself for cracks, unless you decide to ditch them altogether and convert to the open system.
 
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