Short version ... For those that don't feel like reading a novel scroll to the bottom for the final fix, but I think you might find the story and the troubleshooting steps intriguing.
Long version, here goes.
So been a KJ owner for about three years, but only lurked on here and thought I would give back with writing about my overheating experience and the final fix.
So, problem started when the AC clutch locked up and took out the serpentine belt. Ordered a new clutch and went to work. Could not for the life of me get the old clutch off, so after a few days of trying everything under the sun the Jeep sat next to the house.
Fast forward to about a year ago and I really needed another vehicle and so I started working on the Jeep again, finally got out the grinder and went to town on the old AC clutch and got it off, but in the process buggered up the threads for the retaining bolt, as well as the spline a bit too. After beating the new clutch on realized it wasn't going anywhere so put her back together and started driving it around town and it was fine, so start to drive back and for to work about 40 miles each way.
By now you're probably asking, where's the overheating? Get to it already! So here goes. On the third day it overheated on the way to work. Everything blowing out the expansion tank. Let it cool and drove some more until I could get to some water, and boy was she hot (good for Women, bad for vehicles). Opened the bleed screw to pour in water and just blew out steam for the first gallon. Anyhow, checked everything the next morning and on the way home from work she overheated again. This time water was pouring out the water pump and had to have it towed the rest of the way home.
So, onto the water pump replacement, new pump installed, belt installed, and everything topped off. Went for a drive around town and seemed fixed.
On the way to work guess what... She overheated again. repeat and rinse for about three days, finally decide to park it again for almost a year. Then last month decided I need a winter vehicle again, so on to the repair. Replaced thermostat, flushed entire cooling system and went for another drive around town, and she seemed fixed, but alas it was folly. On the way to work she overheated again, and again on the way home. By this time, I was carrying 3-4 gallons of water with me just in case.
So went through it again at home and couldn't see anything wrong with it but did notice the tensioner was bad and moving a lot so decided to replace it. Put it all back together and started it and after it warmed up a bit decided to top off the coolant and when I went to open the bleed screw and it blew off and water was shooting out of it al the way to the hood. Then I thought, could the water pump be turning the wrong way? No that's not really possible, is it? My KJ has had the radiator support replaced so has no stickers on it, so went online for a belt diagram and just in case anyone was wondering, yes you can put the belt on in a way that it routs properly, as in flats on flats and ribs on ribs, and you can get the water pump to run the wrong direction.
So, I say to myself, Duh, water pump running wrong way, maybe doesn't let thermostat heat up or water is circulated wrong direction, so "FIXED" right? Wrong... next day it overheated again on the way to work. Then I started thinking what else can it be? then I realized it overheats at almost the exact same place every time, so what can it be? Head gasket? Oh man, I hope not.
So got a head gasket coolant test kit and it tested fine, not a drop of exhaust in the coolant.
I finally hooked up my ODB2 dongle and app so I could monitor temps, seems that it runs at 100-201 for a long time, then it bumps up to 203 for a bit and then 206 for a few minutes, then started climing through 210 and about then my heat starts blowing cold and that's followed by 220-226 and I start seeing steam. So, my next thought is water pump impellor slipping, or some other high speed cavitation problem, so the next day I drove it home again, this time at 45mph as I've never had it overheat while idling or while just running around town.
Guess what.... Nope not it, still overheated, but well before the same place it usually overheated, so I think, AHA, its time related not speed or miles. What else can it be?
Still stumped I looked at what I've Replaced:
Water Pump, Hoses, Thermostat and flushed the system three different times.
So last thing I can think of is the radiator, even though water flows through it pretty well, I figure there's no way thats it, but I've tried everything else so what do I have to loose but more money and time.
So new radiator comes in, flushed the system, boil tested both the new and old thermostat (they both functioned correctly) and decided to install a metal impellor water pump even though after removing the old one it seemed to be doing OK, but was worried the excessive heat had reduced the life of the bearing and seal. Refilled again with proper coolant and ran it again, this time let it sit running for almost two hours. Stayed at 199-201 forever, then started climbing again past 203, 206, 210... I thought great here we go again. Then it hit 217 and I decided to turn on the AC to get the fan to come on and the temp dropped again to 201. Hmm, bad fan? So let it climb again, 217, 220, 226....bang, fan came on by itself, temp back to 201. Scratch head and decide to let it sit for another 20-30 minutes and temp rises, fan comes on, temp goes back down multiple times just as it should. Take it for an hour-long drive, watching the ODB2 temps and it stays between 199 and 203. Pull into a parking lot and let it idle, temps eventually climb to 226 and fan comes on and back to normal. Drive it home and for the last 4 days it's been perfect. Re-ran the head gasket leak test and it's got no contamination.
So finally. FIXED. I'm guessing that the radiator, although flowing was not flowing well enough. But in the long run, I now had a nearly new cooling system. And it wasn't really too hard to replace the radiator so no harm no foul.
Thanks for the long read, and I hope this helps someone else.
Randy
Long version, here goes.
So been a KJ owner for about three years, but only lurked on here and thought I would give back with writing about my overheating experience and the final fix.
So, problem started when the AC clutch locked up and took out the serpentine belt. Ordered a new clutch and went to work. Could not for the life of me get the old clutch off, so after a few days of trying everything under the sun the Jeep sat next to the house.
Fast forward to about a year ago and I really needed another vehicle and so I started working on the Jeep again, finally got out the grinder and went to town on the old AC clutch and got it off, but in the process buggered up the threads for the retaining bolt, as well as the spline a bit too. After beating the new clutch on realized it wasn't going anywhere so put her back together and started driving it around town and it was fine, so start to drive back and for to work about 40 miles each way.
By now you're probably asking, where's the overheating? Get to it already! So here goes. On the third day it overheated on the way to work. Everything blowing out the expansion tank. Let it cool and drove some more until I could get to some water, and boy was she hot (good for Women, bad for vehicles). Opened the bleed screw to pour in water and just blew out steam for the first gallon. Anyhow, checked everything the next morning and on the way home from work she overheated again. This time water was pouring out the water pump and had to have it towed the rest of the way home.
So, onto the water pump replacement, new pump installed, belt installed, and everything topped off. Went for a drive around town and seemed fixed.
On the way to work guess what... She overheated again. repeat and rinse for about three days, finally decide to park it again for almost a year. Then last month decided I need a winter vehicle again, so on to the repair. Replaced thermostat, flushed entire cooling system and went for another drive around town, and she seemed fixed, but alas it was folly. On the way to work she overheated again, and again on the way home. By this time, I was carrying 3-4 gallons of water with me just in case.
So went through it again at home and couldn't see anything wrong with it but did notice the tensioner was bad and moving a lot so decided to replace it. Put it all back together and started it and after it warmed up a bit decided to top off the coolant and when I went to open the bleed screw and it blew off and water was shooting out of it al the way to the hood. Then I thought, could the water pump be turning the wrong way? No that's not really possible, is it? My KJ has had the radiator support replaced so has no stickers on it, so went online for a belt diagram and just in case anyone was wondering, yes you can put the belt on in a way that it routs properly, as in flats on flats and ribs on ribs, and you can get the water pump to run the wrong direction.
So, I say to myself, Duh, water pump running wrong way, maybe doesn't let thermostat heat up or water is circulated wrong direction, so "FIXED" right? Wrong... next day it overheated again on the way to work. Then I started thinking what else can it be? then I realized it overheats at almost the exact same place every time, so what can it be? Head gasket? Oh man, I hope not.
So got a head gasket coolant test kit and it tested fine, not a drop of exhaust in the coolant.
I finally hooked up my ODB2 dongle and app so I could monitor temps, seems that it runs at 100-201 for a long time, then it bumps up to 203 for a bit and then 206 for a few minutes, then started climing through 210 and about then my heat starts blowing cold and that's followed by 220-226 and I start seeing steam. So, my next thought is water pump impellor slipping, or some other high speed cavitation problem, so the next day I drove it home again, this time at 45mph as I've never had it overheat while idling or while just running around town.
Guess what.... Nope not it, still overheated, but well before the same place it usually overheated, so I think, AHA, its time related not speed or miles. What else can it be?
Still stumped I looked at what I've Replaced:
Water Pump, Hoses, Thermostat and flushed the system three different times.
So last thing I can think of is the radiator, even though water flows through it pretty well, I figure there's no way thats it, but I've tried everything else so what do I have to loose but more money and time.
So new radiator comes in, flushed the system, boil tested both the new and old thermostat (they both functioned correctly) and decided to install a metal impellor water pump even though after removing the old one it seemed to be doing OK, but was worried the excessive heat had reduced the life of the bearing and seal. Refilled again with proper coolant and ran it again, this time let it sit running for almost two hours. Stayed at 199-201 forever, then started climbing again past 203, 206, 210... I thought great here we go again. Then it hit 217 and I decided to turn on the AC to get the fan to come on and the temp dropped again to 201. Hmm, bad fan? So let it climb again, 217, 220, 226....bang, fan came on by itself, temp back to 201. Scratch head and decide to let it sit for another 20-30 minutes and temp rises, fan comes on, temp goes back down multiple times just as it should. Take it for an hour-long drive, watching the ODB2 temps and it stays between 199 and 203. Pull into a parking lot and let it idle, temps eventually climb to 226 and fan comes on and back to normal. Drive it home and for the last 4 days it's been perfect. Re-ran the head gasket leak test and it's got no contamination.
So finally. FIXED. I'm guessing that the radiator, although flowing was not flowing well enough. But in the long run, I now had a nearly new cooling system. And it wasn't really too hard to replace the radiator so no harm no foul.
Thanks for the long read, and I hope this helps someone else.
Randy
