Re: Over heated Jeep
I had a '99 XJ, 6 cyl, factory HD radiator, used to tow a boat and also experienced something similar.
For no apparent reason, after hauling across town or miles down the highway, the temp gauge would start to spike. Hills may have been a trigger, but it could also only have been just a slight change in grade.
I investigated everything everybody has discussed so far, even to the point of scientifically measuring waterpump output volume/pressure, radiator flow, and flow through the block.
Drove me nuts for months, more than a couple of times causing me to sit on the shoulder letting the engine cool.
Finally, an old school mechanic I know suggested I "burp" the cooling system. He said some cooling system designs have a high spot where air can get trapped and temporarily impeed flow. That the condition is inconsistant, but usually appears after cooling system maintenance.
We raised the Jeep's front on drive-up stands and warmed it up as near operating temp as possible with the radiator cap off. Then we shut it down, let it cool back to ambient, topped it up through the radiator with 50/50, and closed the system back up.
Back down on the level, we pulled most of the backup anti-freeze out of the reservoir anticipating some overflow and fired up the engine.
At operating temp the reservoir rose a normal amount, upon cooling it pulled the same amount back into the system. With that, I filled the reservoir to its normal cold level...
That was at 60k, I drove that Jeep another 100k and never had another overheat.
Tom,
I had a '99 XJ, 6 cyl, factory HD radiator, used to tow a boat and also experienced something similar.
For no apparent reason, after hauling across town or miles down the highway, the temp gauge would start to spike. Hills may have been a trigger, but it could also only have been just a slight change in grade.
I investigated everything everybody has discussed so far, even to the point of scientifically measuring waterpump output volume/pressure, radiator flow, and flow through the block.
Drove me nuts for months, more than a couple of times causing me to sit on the shoulder letting the engine cool.
Finally, an old school mechanic I know suggested I "burp" the cooling system. He said some cooling system designs have a high spot where air can get trapped and temporarily impeed flow. That the condition is inconsistant, but usually appears after cooling system maintenance.
We raised the Jeep's front on drive-up stands and warmed it up as near operating temp as possible with the radiator cap off. Then we shut it down, let it cool back to ambient, topped it up through the radiator with 50/50, and closed the system back up.
Back down on the level, we pulled most of the backup anti-freeze out of the reservoir anticipating some overflow and fired up the engine.
At operating temp the reservoir rose a normal amount, upon cooling it pulled the same amount back into the system. With that, I filled the reservoir to its normal cold level...
That was at 60k, I drove that Jeep another 100k and never had another overheat.
