I opened the hood yesterday morning on my '07 LBZ. It had been sitting over night and the morning was cool. I noticed the upper radiator hose was collapsed flat about a foot in the center of its length. Is this normal? I know it doesn't have a spring in the hose to help keep its shape. When I unscrewed the cap on the overflow tank, the hose rounded right up. The truck has only about 4K on it. I guess I never looked under the hood before when it was cold. Oh, the day before I drove it about 100 miles mostly highway, then parked it in my driveway.:wtf1:

Mine does it too, There is a thread here on this. Basically the vent on the cap gets clogged, just wash it with soap and water and it will be fine. Im sure it has to do with the crappy DEXCOOL.

I cleaned mine out as Tim described and it corrected the problem. Some guys go ahead and buy a new cap, though.

So what if you dont know this is happening? Will it hurt anything? Or I should say has it hurt anything?

Open your hood when the truck has been sitting overnight and you will be able to see if the hose has collapsed. I don't know that it hurts anything, but is an indicator that your coolant system is not "breathing" as it should via the overflow cap vent.

mine did that after the dealer put in a new waterpump,i just added more antifreeze and that fixed that

seems to be normal, mine does it too

mine did this with only 2000 miles on truck found low dexcool filled to cold line no more problems

mine did the same thing, I cleaned the cap with hot water and soap, did not fix the issue so I got one from dealer at $12:)
issue solved!

I just posted about this about a week ago. I went and got a new cap, still same problem. I will try another brand of cap at another store to see if it is a flaw with the company. I do not like the way it looks when it is colla[sed like that. I also looked and my over flow tank was nearly empty, but when I unscrewed the cap, it filled back up from the coolant in the system. WTF?

i don't think you guys need to keep replacing caps,just fill the cooling system to the full line

I just cleaned mine with some soapy water and blew it with compressed air and it has been working for months.

You all could look @ this two ways. First of all if your truck is still under warranty take it back to the dealer and have them replace the radiator cap @ no charge. After all if you took the truck into a shop or a dealer for this type of diagnois/ repair and the truck was not under warranty wouldn't they call you up and tell you that the cap needs to be replaced for said dollor amount... Second washing the cap, filling/ topping off the system does not always correct the problems. It may affect the efficiency of the system but more than likely there will still be a intermittent problem w/ the cap. Dont take the chance on a 45K $ truck!:cool:

After reading the replies, I looked at my cap. It doesn't have a vent hole that I can see. It appears the overflow tank is also the pressure tank. The cap says "do not open hot!" and 15# psi. The coolant level is at the cold fill line and the cap did not appear dirty. I blew it out with compressed air anyway and will look tomorrow morning to see if the hose is collapsed. If so, it's off to the dealer. I'm dreading taking it in after reading some of the horror threads concerning dealer service. Anyone know of any tech. bulletins regarding this problem. I thought about getting a hose from an auto parts house and taking the spring out and putting it in mine. Any thoughts?

I would not even take my truck to the dealer for a $12 rad cap if it was under warranty. Everytime i take my truck in for warranty work it is a hassle to get anything fixed. Dealerships are horrible to deal with:mad:. I am a technician myself and if i treated customers like the dealership treats us, our business would have closed the doors a long time ago!

A flat upper rad hose means you have air in system, which prevents system reaching proper pressure, potentially reducing coolant flow due to low suction pressure at water pump, and air in system = poor heat transfer..
Replacing the cap should help. Watch your tank level. The level will drop as air comes out of system, so it may need to be filled. Fill to the plastic tab on tank, which is above the Cold Fill arrow and mid-tank seam.
Below is a link, (thanks to killerbee), to a great explanation of our coolant expansion tank. Open the CANOWORMS at post #1:
http://dieselplace.com/forum/showthread.php?t=49060&highlight=flat+hose