Evening to all. Just picked up a 2015 Jeep Wrangler Unlimited Sahara, and I'm hoping that I didn't inherit someone else's headache. After purchase drove it 2 hours on highway to get home. Next day drove another 2 hour round trip with no problems. Ran heat and AC. Next day drove to work and turned on heater and it started to overheat. It would heay up to thhe point of warning coming on after parking the temp would drop back to normal. Short of it had to drive and stop all the way back home. Tried the burp the system and all I got was antifreeze back flowing out. Took to mechanic and he replaced the thermostat. Ran fine for a week and a half and started again. My mechanic thinks its a head gasket. but he didn't do all the tests. I'm going to perform a block test and then a leak down. If these prove negative might it be the wart pump? I did notice that after a week of sitting there was still pressure under the radiator cap which I don;t think is good. Looking for ideas and suggestions.
Overheating
- Thread starter Electric Banana
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- 3.6 overheat overheat
You need a scanner with live data. What’s the temp reading off the scanner?
Also, if your electric fan isn’t coming on or gradually failing, it would overheat most likely. Outside temps would be good to know as well.
Pressure is created by the expansion of the coolant when heated. The water pump really just moves the coolant around. It doesn’t create pressure. If it’s maintaining some pressure after being shut off for awhile, that means you don’t have a leak.
Also, if your electric fan isn’t coming on or gradually failing, it would overheat most likely. Outside temps would be good to know as well.
Pressure is created by the expansion of the coolant when heated. The water pump really just moves the coolant around. It doesn’t create pressure. If it’s maintaining some pressure after being shut off for awhile, that means you don’t have a leak.
There should not be pressure after a week of sitting! Honestly, after 12 hours there shouldn't be pressure. It's either a head gasket leak or a cracked block from it overheating. Have you looked under your oil cap for any light colored chocolate milk?
We don’t know what the OP means by that statement. We also don’t have enough info to say positively it’s a head gasket or a cracked block. OP needs to do some testing before drawing conclusions.
Looking under the oil cap is a good thing to check. Hopefully the OP will come back and update us on his findings.
Pressure is relative. Could be just a pound above ambient and you might get some overflow from the fill neck.
The chocolate milk check is dreaded around here. I have to maintain a few forklifts.
Since the first day been checking the oil, not finding any water in the oil and not seeing smoke from the tailpipe. Pulled the thermostat to check if it was good and found it was working. I'm going to drain the radiator and refill. Waiting for combustion gas tester to be delivered.
Old school way. Boiling water. Althought, I think the OMP is 203 degrees. I think my mechanic may have put in something higher. Upon heating the thermostat opened but not a lot. After removing from boiling water I saw the thermostat slowly close.
Side note. Looking back at the work that was done to replace thermostat found they put in .75 gallon of orange antifreeze where I think the 15 Wrangler uses the purple stuff. Think this is causing the overheat. Going to drian and reinstall all purple.
If you mix different types of coolant together they will cause the coolant to get thick and not flow like it's supposed to.
Color hasn’t been standardized in coolants. You want an OAT coolant. Do NOT mix OAT and HOAT. Personally, to be safe I don’t even mix brands of coolant. I use Peak Final Charge any time I need an OAT coolant.
I doubt the coolant color has any relevance to your issues. If they mixed an OAT and a HOAT coolant, that could be causing your issues. Orange coolant is usually OAT but you can’t rely on the color.
I doubt the coolant is your problem UNLESS they mixed coolant types.
Again, what does the live data say on a scanner?
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Mr Mopar
After I checked the thermostat I ran the motor to check. Start temperature was 65. Ran the heater full blast but never got heat in the cabin. Temperature hovered at 225 and then slowly climbed up to 260 and overheat alarm sounded. Turn off motor and check for leaks. Didn’t find anything and still no water in oil and no smoke from tailpipe. I’m going to drain the radiator and put in new antifreeze
After I checked the thermostat I ran the motor to check. Start temperature was 65. Ran the heater full blast but never got heat in the cabin. Temperature hovered at 225 and then slowly climbed up to 260 and overheat alarm sounded. Turn off motor and check for leaks. Didn’t find anything and still no water in oil and no smoke from tailpipe. I’m going to drain the radiator and put in new antifreeze
Make sure you bleed the radiator well.
Any trouble codes?
Is the radiator fan running when the temps are in the 225-230 range? Does the fan run when the AC is on?
I’d take a laser thermometer and go around checking the hot and cooled side of the radiator when the engine is warm looking for major differences.
It's got codes but not for cooling system. I will check again tomorrow after work.
Sometimes a certain code is caused by something other than what it appears. For example, a fuel injector can cause misfires even though most people think of ignition issues with misfire codes.
The best and easiest way to get air out of the cooling system is to jack up the front of the Jeep at least 6". Then take radiator cap off and start engine and let it idle, add coolant until it's full.