Ok so this is my first post for this site and I am need of some real help. I was a cummins tech prior to joining the military but am a bit out of the loop now. I have a 07 dodge with 5.9 and am losing coolant slowly but noticeable. I loose a little less than a half gallon in 120miles.

I have taken it to the local dodge dealer twice as it is still under warranty both times I get the same response we have no idea. So here is what they have done. Pressure checked the coolant system and to no leak. The had it and drove it 80 miles and they said the level didn't move at all. They just left it at that.
My last hope is to replace the radiator cap as I can see some water around it but other than that I have no idea.
I can give more info if you need it to help with answer.

 

This probly will not acount for that much of a loss. But mine and several others have had the transfer hose from the block to the heater core come loose. I will try to find the pict and post it up. You just got to tighten it and that leak will stop.

 

The dealer mentioned that but not sure if he tightened it but I am watching that
Thanks

 

I don't have a pic, but the other trouble spot is the hose that goes to the overflow tank. Where it connects to the filler neck of the rad the factory doesn't bother to put a clamp on. Several people including me have had it leak there. Get a small hose clamp, I like the spring type, but any will do. Since you said you are seeing coolant near the filler cap, that is most likely the culprit. I also had the hose in the picture above leak, it only does it in the fall when temps cool off. I replaced mine with an upgraded piece from the factory. Pics below. BTW, your dealer doesn't sound like they have much on the ball.

 

Where is your top pictured hose located at

 

It goes in place of the hose shown in the post above mine.

Old



New

 

Also, put a zip tie or clamp on the hose coming from the overflow tube. This was the leak you saw at your radiator cap, it will leave a nice pink/white residue.

 

Did they pressure check the system when the engine was hot? (hot = thermostat open)

Do you smell a sweet smell in the exhaust?

Do you get white smoke from the exhaust?

If it's not leaking, the engine is eating it.

 

When they pressure checked it I am not sure if the thermostat was open but I questioned that and never got a straight answer. I don't smell it in the exhaust and I don't get white smoke wierd I know but I don't know quite which way to go from here. Not so say it is not there and I have not noticed it at the right time as this problem seems to be some what engine temp dependent.