Hi there
I have noticed something weird on my 2009 JKU when I opened the engine cover. My upper coolant pipe is squashed when the engine is cool. When I open the radiator cap, it rounds up back to it's cylindrical shape.
I have no heating engine issues,no white smoke from the exhaust system, no water under the car, and my water reservoir is between minimum and maximum. I filled the reservoir to max, but it still happens.
I decided to check and see if there is an engine gasket burst, by filling the radiator with fluid to its max and look for bubble when I start and run the engine. I noticed that there was about a quarter gallon for fluid missing. ???.
The good news was there were no bubbles. Well maybe two or three but then it stop burping.

I was wondering how come there were missing water in the radiator, while the reservoir is full? Any ideas?
I tested the pipe between the cap and the reservoir and its clean. Isn't the reservoir suppose to keep the radiator full?
I always made sure the reservoir is full. I never checked the radiator cap. Which one should I check then?

Thanks

StormJKU

 

Since the reservoir is at a sufficient level and the hose between the reservoir and radiator is clean; then the problem is more than likely your radiator cap. It is supposed to lift and allow coolant to flow toward the reservoir as the engine heats up and the cooling system pressurizes. When the engine shuts off and the system pressure drops the cap is supposed lift to allow the coolant to return to fill the void in the radiator.

 

Thanks for the quick reply.

I got the same answer from another source saying the valve on the cap might be faulty.
I have the original 18lbs aluminum cap, and I noticed it has been replaced by Mopar with a new plastic covered 17lbs one.
I'll stop by the dealer today and get a new one, replace it and let you guys know tomorrow.
Thanks again.

-StormJKU

 

Hey Charles

That seems to do the trick.
I changed the cap, filled it up till the top and no more pipe shrink.

Thanks for all the help

StormJKU