2002 TJ, I put on a new fan clutch, thermostat and housing, new radiator with a flush and new coolant. Jeep runs perfectly fine when driving but when idle for about 15-20 min it will go to about 225. In the summer in Arizona where temps are 110f+ will this cause my jeep to overheat? Pic shows 215 but it goes up to about 225. Thanks
Are these high idle temperatures normal?
- Thread starter limeliam
- Start date
KennethS
TJ Expert
What you described is typical of poor air flow across the radiator at idle speed.
Things that come to mind:
Test the fan clutch to ensure it's good.
Make sure there is nothing restricting air flow across the radiator: shroud in place, no debris between the radiator and AC condenser.
Things that come to mind:
Test the fan clutch to ensure it's good.
Make sure there is nothing restricting air flow across the radiator: shroud in place, no debris between the radiator and AC condenser.
In addition, make sure your radiator is full.
Can't tell you how many times I've seen this issue and it's due to the radiator being less than full.
I will say that having lived in Arizona, my TJ would always idle at higher than normal temps, especially in the summer.
Can't tell you how many times I've seen this issue and it's due to the radiator being less than full.
I will say that having lived in Arizona, my TJ would always idle at higher than normal temps, especially in the summer.
Mine behaves similarly in triple digit temps. New Mopar radiator, new water pump, new T-stat and the engine is recent and clean. Fan clutch tested good, fully locked when hot as verified with a hand held tach. If I am stuck at a drive thru for 10-15 min and leave the AC running it will go over 220F, as high as 224F if I recall, measured with Torque Pro. I installed a compressor kill switch that I can switch off in those situations and it helps. Mostly though as long as I keep moving things are fine.
Have not had it boil over while running but if I do not kill the AC a minute or so before stopping it will boil into the reservoir but not over.
Someone on here did a fan and clutch mod from another vehicle, a Ford Explorer maybe? and said it keeps it cooler in desert temps.
Have not had it boil over while running but if I do not kill the AC a minute or so before stopping it will boil into the reservoir but not over.
Someone on here did a fan and clutch mod from another vehicle, a Ford Explorer maybe? and said it keeps it cooler in desert temps.
In 110 I think this is probably closer to normal than the exception. A fan is not going to move the volume of air as driving.
Make sure you have the correct mix of coolant. A 50/50 mix gives a 265 boiling point, which you do not have. The danger to an engine is not hot water, it is hot air caused by boiling over.
Completely clean/flush your cooling system including taking the drain plug out of the block and refill using proper mix using distilled water.
Make sure you have the correct mix of coolant. A 50/50 mix gives a 265 boiling point, which you do not have. The danger to an engine is not hot water, it is hot air caused by boiling over.
Completely clean/flush your cooling system including taking the drain plug out of the block and refill using proper mix using distilled water.
Might also want to confirm that temp gauge is accurate. I used to use temp sticks that melt, but many years ago started using a good quality IR digital checker...the ones at Harbor freight are fairly accurate and dont cost much.
KennethS
TJ Expert
Mine does this still with the new fan clutch. No clue why. I think I'm due for another coolant flush. My entire cooling system is new(ish) except my radiator. I saw a post where a dude took out the petcock on the bottom of the radiator completely out and got a bunch of sediment out - I'm going to try that too.
Circulate some CLR (or any of the other flush fluids) through the system for a while (like 2 days) and then drain the system. I like CLR because it dissolves the rust and puts it in solution which is drained out. If you have rust particles in the bottom of the radiator they are the next ones to get sucked into the pump and pushed into the heater core greatly increasing the chance for a clog as the cores passages are significantly smaller than the radiator. If you are getting rust in your system an inline coolant filter should be used to keep the particles out of the core to help eliminate that expensive repair.
After completely draining and a quick rinse with the hose and draining the block, I cut my return hose to the core and insert a fitting into each side. On the side that goes back to the block I attach a clear hose long enough to reach outside of the tire and put it in a big 10 gallon bucket. The other side I do the same except I attach a cheap submersible pump. Add distilled water and CLR and turn the pump on. You will see the fluid move through the entire system and end up in the bucket to be recirculated again and again leaving the junk in the bottom of the bucket.
Notes...suspend your pump so it is not picking up the debris deposited into the bucket. You need to remove the thermostat or the fluid won't flow. You will also need to plug off the overflow hose or you will flood the overflow jug. If you add some of the solution to the jug, it will remove the crud stuck to the sides. Change the water/solution as needed until it is clean. Flush it for the last time with only distilled water. Drain everything including the block, reconnect the core hose and fill with proper coolant. You can run this setup as long as you want (days) without issue. Just do it until it is clean.
KennethS
TJ Expert
If you want to get crud out of the heater core and radiator, running water from a hose (which I’ve done multiple times) doesn’t do nearly as much as attaching water and compressed air to a gun (I use the OTC tool). Cycling the air trigger adds a hammering effect to the water, and the results are astounding.
Radiator: Run clear hose from the top port to a bucket. The attach the gun to a spare top hose (larger end fits to the bottom port).
Heater core: Attach clear drain hose (using barb fittings) to the 3/4” rubber hose and clear hose on the other 5/8” rubber hose for the gun. Swap ends and repeat.
Clamp all ends or they will pop off under pressure.
Radiator: Run clear hose from the top port to a bucket. The attach the gun to a spare top hose (larger end fits to the bottom port).
Heater core: Attach clear drain hose (using barb fittings) to the 3/4” rubber hose and clear hose on the other 5/8” rubber hose for the gun. Swap ends and repeat.
Clamp all ends or they will pop off under pressure.
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This won’t cut it.
If the issue isn’t coolant level, the fan clutch, or direction of your fan, I’d change the radiator bc it’s might not be efficient enough to cool when less CFMs are being pulled through it.
Guys, check your radiator cap, if everything else does not fix the issue.
I went through 2 new off brand caps before trying a MOPAR cap, which fixed my problem, similar to yours.
I went through 2 new off brand caps before trying a MOPAR cap, which fixed my problem, similar to yours.
I remember in an older thread about temps we were talking about AC and if I recall your AC was not working at the time, or you didn't check temps while it was running. Did you get the AC going? I have temps similar to the OP with AC on and everything is new and confirmed working as designed. New Mopar radiator less than 5,000 miles on it. New Mopar WP/Robt Shaw stat, fan clutch tested shows 100% lockup, cooling system spotless, new Mopar cap and recovery bottle.
There are past threads where I recall some people saying it is normal, but I still don't know. I also have the black inserts in my grill which I plan to remove this year just to see if that makes a difference, some say it won't and some say it will. It's the last thing I have to try.
Your input and a couple others here has a lot of weight since you live where both the OP and I live. Sometimes folks who don't live here don't fully understand what we deal with in the summer.
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