Radiator boiling after replacing entire cooling system (including radiator)
- Thread starter JohnJ78
- Start date
Only one page back so I checked.
Assuming all of the above parts are good, that's pretty much the entire cooling system minus the fan clutch. Does it overheat while driving down the highway or just at idle?
When I replaced everything in my cooling system it also overheated, bigly. As soon as I burped the system and got all the air out, problem solved. I live in So. Cal high desert and it gets up above 110 deg. and, except for that one time when I had air in the system, I don't have any issues with overheating.
I read original post and it said fan clutch spins fine ? As it heats up it should get harder to spin or lock up when temp overheats. All the stuff you have replaced I can't believe you haven't replaced fan clutch ! Does it overheat while cruising or at idle ? When you shut it off hot is it hard to spin fan ?
That's perfectly normal, the engine is 210f and it's located immediately underneath the uninsulated hood. Also the radiator is of course going to be WAY too hot to touch shortly after the engine is running.
Anything much over 140f degrees is going to be too hot to touch. Holding your hand on anything over 140f more than 4-5 seconds can produce burns so don't plan on touching a radiator that was just at or very close to 210 degrees until it has been cooling off for a very long time.
Agreed, but it boiling over isn't supposed to happen. It's too hot unless he just had no rad cap on it at all.
My mechanic said it was spinning ok. Cost of clutch fan was insane here so I left that, but maybe I should swap it out after all. When it overheated the other day, the fan was able to be turned with minimal-medium effort and it was not locked, so maybe I should get a new one. Can I just get a bolt on fan and do away with the clutch, seems like a mighty waste of money?
Brand new cap, water level was down in the overflow and I've topped up once in a month, and I just really kept an eye on overflow bottle level, so radiator level could have been down and I didn't notice. I still suspect head gasket even though no bubbles and done chemical test myself.... coolants going somewhere. When it boiled over the other day spewing coolant out the overflow bottle, it ended up needing 1.5 liters of coolant when it finally cooled down.
Clutch fan ordered $100. Will try that. All this time I was thinking they were $500+ due to website price error.
Defiantly something wrong John I drove yesterday in the Perth heat and then again today , It was 42c (107) at 430pm and my gauge didnt go over half.
I would remove them big spotlights first as you only seem to overheat on really hot days, flowing air temp today and yesterday were much hotter in my TJ than the still air and the reason I wont go topless.
Those 7 big oblong holes in the front grill are there for a reason, blocked air flow can be the same as a blocked radiator.
Also did you have your A/C on full? Is the heater working?
I had a HQ (Chevy) 6 cylinder years ago that came with a Yellow Terror head when I bought it, it used to get so hot the headers would sometimes glow and melt the positive wire to the starter causing the starter to engage, when I finally took the head off the gasket had been put on round the wrong way blocking some of the water jacket holes! Thats why it was overheating but showing no sighs of a blown head gasket or cracked head.
If its not the lights blocking air flow then it could still be the thermostat not always opening. If it was a blown head gasket it would overheat regardless not just on super hot days.
Check your harmonic balancer.
I would remove them big spotlights first as you only seem to overheat on really hot days, flowing air temp today and yesterday were much hotter in my TJ than the still air and the reason I wont go topless.
Those 7 big oblong holes in the front grill are there for a reason, blocked air flow can be the same as a blocked radiator.
Also did you have your A/C on full? Is the heater working?
I had a HQ (Chevy) 6 cylinder years ago that came with a Yellow Terror head when I bought it, it used to get so hot the headers would sometimes glow and melt the positive wire to the starter causing the starter to engage, when I finally took the head off the gasket had been put on round the wrong way blocking some of the water jacket holes! Thats why it was overheating but showing no sighs of a blown head gasket or cracked head.
If its not the lights blocking air flow then it could still be the thermostat not always opening. If it was a blown head gasket it would overheat regardless not just on super hot days.
Check your harmonic balancer.
Yeah I can imagine the air is eddying around those big spotlights and not efficiently passing through radiator, they actually take up nearly half the grill space.
A/c was on full. Heater core is bypassed, my thinking was it may be weak link for my cooling system and it may start leaking eventually.... apparently can't get them here in perth any more?
I've got a new harmonic balancer here waiting to go on when I get the energy. Also a high flow thermostat, definitely all worth a try. Thanks
Yes, all I could get. I live in Australia. Maybe will order Mopar, are they copper?
They are aluminum. That's not your problem though. You never answered my question if it gets hot driving at highway speeds or just at idle/city driving.
No it does not get hot idling or on highway (gauge wise), its at 100 degress (celsius).... I can feel incredible heat coming through the firewall and under the gearbox, I even put thermal insulation under there to minimize it.
Before I did all the water pump, radiator etc, it was boiling every time when I would cut the engine. Since my cooling system revamp, the gauge sits at halfway always except one day when it hit 110 (43 degree day), but still so much under hood heat always. It boiled the other day when I switched the engine off, but the coolant must have been low, I remember seeing it a few days before getting low in the overflow bottle.
So it doesn't overheat while running, either at idle or at speed, but it's boiling over when you shut it off? It would only do that because it's either too hot or the system isn't pressurized like it's supposed to be.
So your know anybody with a coolant pressure tester kit?
So your know anybody with a coolant pressure tester kit?
No, but I will take it to my local radiator specialist to check. On the phone this dude told me to run really low glycol coolent because water is far more capable of getting rid of the heat. I'm running 33% ethylene glycol atm.
That was sound advice, especially for your climate. Antifreeze actually does raise the boiling point a bit, but doesn't cool as well as water and with your radiator cap on and functioning, it should be a non-issue. So does it boil when you know the system is topped up with coolant? If not, that changes the troubleshooting dramatically.
We are into this this far so let's continue ! See if it overheats or boils after driving without using a/C. Don't use it and see what happens, then change fan clutch like I suggested. Fan clutch pulls air over radiator and condenser !!! The temperature of a/C condenser get get well over 300 degrees in your climate. The condenser is attached to radiator and must have air flow to keep pressure/temp correct. Check air flow or blockage at condenser.
Those big lights in front can reduce air flow through radiator/condenser while driving buttttttt fan clutch should be able to pull air over them if shroud is ok and there's no blockage. So try driving without a/C on and see what happens.
Those big lights in front can reduce air flow through radiator/condenser while driving buttttttt fan clutch should be able to pull air over them if shroud is ok and there's no blockage. So try driving without a/C on and see what happens.
This^^. Boiling after shut off is definately a sign of loosing pressure somewhere. Pressure drops, lowering the boiling point of the coolant, and it starts to boil. Most likely the cap. I believe you said you had replaced that as well, but it sure sounds like a cap problem. Did you get the correct 18 pound cap?
The exact thing happened to me. It would run fine, and when I parked it I would come back to coolant all over the ground. Turned out to be a cut in the cap gasket. Fixed that and I’ve not had a problem since. But, it took me months to figure it out.
MrMark52
TJ Enthusiast
And not that it’s going to help the boil over problem that much, but if you used anything other than an OEM temperature sensor then what your seeing on the dash gauge is nothing but fallacies.
I just went thru a similar situation of what the dash gauge was telling me versus what the engine was really doing. Fortunately when the gauge was i the red, the engine was at proper operating temperature.
And FAIK - a “high flow” thermostate is another fallacie of thought. Todays cooling systems are well designed for extreme ambient temperatures, to include the thermostats.
And, you need to make sure the A/C condenser coil is clean. As others have tried to tell you, I doubt the lights are your problem, but if you think they are, take ‘em off! But if the condenser coil isn’t clean, your engine heat will rise while your A/C cooling will suffer.
And disconnecting the heater core decreases the coolant cooling capacity - not that you would want heating inside the Jeep when the Ambient is as hot as you say.
Just my $.02 worth.
I just went thru a similar situation of what the dash gauge was telling me versus what the engine was really doing. Fortunately when the gauge was i the red, the engine was at proper operating temperature.
And FAIK - a “high flow” thermostate is another fallacie of thought. Todays cooling systems are well designed for extreme ambient temperatures, to include the thermostats.
And, you need to make sure the A/C condenser coil is clean. As others have tried to tell you, I doubt the lights are your problem, but if you think they are, take ‘em off! But if the condenser coil isn’t clean, your engine heat will rise while your A/C cooling will suffer.
And disconnecting the heater core decreases the coolant cooling capacity - not that you would want heating inside the Jeep when the Ambient is as hot as you say.
Just my $.02 worth.
Similar threads
