I'm chasing an overheating at idle problem that first appeared this April. General info: 2006 LJR, stock 4.0L, 168k miles. New parts installed at 161k miles: Mopar radiator, t-stat, heater core, all 4 heater and radiator hoses, radiator cap.
The first overheating incident happened this April during a trail run. While idling at the side of the road for ~10min, the temp gauge was pegged at 260. I estimate it was running at this temp 5 min or less. There were no obvious signs of trouble/damage after this incident. 1/2 gallon was needed to top it off and burp the system. I could see water flowing and the top hose was firm feeling. Didn't have any leaks or other problems since. . . . but in fairness I've probably driven the Jeep 10 days since April. Damn rain.
After a Sunday drive this week, I decided to decarbonize the cylinder head with water. Everything was going fine until, , . I noticed the coolant in the overflow tank was boiling. Great. So I shut 'er down, then used a towel to crack open (not completely remove) the radiator cap to release steam, relieve pressure. I eventually removed the cap and found a few pieces of rubber gasket shrapnel which peaked my curiosity.
I picked up a new fan clutch since I had two overheat at idle situations. Before diving in for the R&R, I decided to fill and pressure test the cooling system. I used an airlift tool to fill the coolant. When I pressure tested the system, an air leak was discovered between the radiator top tank and core. The radiator is under warranty, so I'll deal with that this week. I still had the old Mopar radiator that came in the Jeep. I flushed the old radiator 'til the water ran clear. Nothing sketchy came out. I installed the new fan clutch, old radiator, airlift filled the coolant, then pressure tested the system. It held steady at 14#.
The test drive was ~8 mile round trip to the quarter car wash to rinse off the engine. No sweet smell from the exhaust, no drips, no leaks. At operating temp the gauge read ~215* and stayed there while driving. When I pulled in to the car wash lot the needle climbed instantly. I shut it off before the needle reached the red zone. Driving home the temp stayed at 215 while air was moving. When I got home I let it idle to see what'd happen. In less than 5min the needle hit red and the check gauges light came on. So, I pulled into the garage, shut 'er down, and jumped on the www.
The next things I'm planning to do are go all-in on flushing the system (Prestone flush & clean, pull t-stat, pull block drain plug), until the new warranty replacement radiator arrives. I expect to be done flushing once the replacement radiator arrives so that I can install a new t-stat and I can verify the proper amount and concentration of coolant is filled. I'm hoping/expecting this is a small problem, but time will tell. What say the WTJF crowd?
The first overheating incident happened this April during a trail run. While idling at the side of the road for ~10min, the temp gauge was pegged at 260. I estimate it was running at this temp 5 min or less. There were no obvious signs of trouble/damage after this incident. 1/2 gallon was needed to top it off and burp the system. I could see water flowing and the top hose was firm feeling. Didn't have any leaks or other problems since. . . . but in fairness I've probably driven the Jeep 10 days since April. Damn rain.
After a Sunday drive this week, I decided to decarbonize the cylinder head with water. Everything was going fine until, , . I noticed the coolant in the overflow tank was boiling. Great. So I shut 'er down, then used a towel to crack open (not completely remove) the radiator cap to release steam, relieve pressure. I eventually removed the cap and found a few pieces of rubber gasket shrapnel which peaked my curiosity.
I picked up a new fan clutch since I had two overheat at idle situations. Before diving in for the R&R, I decided to fill and pressure test the cooling system. I used an airlift tool to fill the coolant. When I pressure tested the system, an air leak was discovered between the radiator top tank and core. The radiator is under warranty, so I'll deal with that this week. I still had the old Mopar radiator that came in the Jeep. I flushed the old radiator 'til the water ran clear. Nothing sketchy came out. I installed the new fan clutch, old radiator, airlift filled the coolant, then pressure tested the system. It held steady at 14#.
The test drive was ~8 mile round trip to the quarter car wash to rinse off the engine. No sweet smell from the exhaust, no drips, no leaks. At operating temp the gauge read ~215* and stayed there while driving. When I pulled in to the car wash lot the needle climbed instantly. I shut it off before the needle reached the red zone. Driving home the temp stayed at 215 while air was moving. When I got home I let it idle to see what'd happen. In less than 5min the needle hit red and the check gauges light came on. So, I pulled into the garage, shut 'er down, and jumped on the www.
The next things I'm planning to do are go all-in on flushing the system (Prestone flush & clean, pull t-stat, pull block drain plug), until the new warranty replacement radiator arrives. I expect to be done flushing once the replacement radiator arrives so that I can install a new t-stat and I can verify the proper amount and concentration of coolant is filled. I'm hoping/expecting this is a small problem, but time will tell. What say the WTJF crowd?