rad cap cold
11-17-2010, 03:38 PM
#1
JK Super Freak
Thread Starter
rad cap cold
What does it mean when my rad cap is cool to the touch immediately after driving for 30 mins. If i release the cap a bit, i hear a hiss then a gurgle sound and the cap begins to get very hot.
Took infrared temp readings and the highest was 185 degrees F at the thermostat housing. Temp gauge in dash is normal.
Took infrared temp readings and the highest was 185 degrees F at the thermostat housing. Temp gauge in dash is normal.
11-19-2010, 05:32 AM
#3
JK Super Freak
Next time the enigne is cold having not been ran that day like overnight check the level in the radiator to make sure it is full. Sounds like it is low and when you crack the cap you are letting air get out which is good since air can cause coolant not to flow properly.
11-19-2010, 05:43 AM
#4
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The hissing sound is the pressure inside your radiator being released. THis means that your cap is working and keeping the pressure in the system which keeps your coolant from boiling.
When you release the pressure in the system, the coolant in the radiator will rise to adjust to the new atmospheric pressure.
I would check my coolant level cold, adjust as necessary, and then keep driving. You need to worry when you don't here the hissing sound, it means that something inyour system is leaking.
It is possible that the cap can be cool to the touch, because typically the coolant in the system does not normally come in contact with the cap. And of course the design of the radiator and its tank will also play into how hot your cap gets under normal operation.
When you release the pressure in the system, the coolant in the radiator will rise to adjust to the new atmospheric pressure.
I would check my coolant level cold, adjust as necessary, and then keep driving. You need to worry when you don't here the hissing sound, it means that something inyour system is leaking.
It is possible that the cap can be cool to the touch, because typically the coolant in the system does not normally come in contact with the cap. And of course the design of the radiator and its tank will also play into how hot your cap gets under normal operation.
11-19-2010, 08:20 AM
#6
JK Super Freak
Thread Starter
usually when the engine has cooled it it was at or near the max line but i have noticed that it has been just above the min line lately.
what would cause the rad fluid to leak out past the cap and on to the ground instead of entering the overflow bottle. The line is clear. It has done this on three different occasions now and i believe the rad cap is the culprit but of course the dealership could "not reproduce".
the last time i checked the level in the overflow was at the min mark and the rad cap was cold. i released a little pressure and the overflow bottle filled to pass the max line?
what would cause the rad fluid to leak out past the cap and on to the ground instead of entering the overflow bottle. The line is clear. It has done this on three different occasions now and i believe the rad cap is the culprit but of course the dealership could "not reproduce".
the last time i checked the level in the overflow was at the min mark and the rad cap was cold. i released a little pressure and the overflow bottle filled to pass the max line?
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11-19-2010, 08:31 AM
#8
JK Enthusiast
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The radiator cap should be at least warm just from the heat right below it. Make sure top of radiator is warm after driving for awhile. At least 15 minutes to make sure thermostat is open. I would make sure you radiator is fun. Obviously don't touch the radiator or open the cap when it's hot. Check it in the am before you drive it. It should be full.