I have a 2002 Ram 1500 Quad 4.7 with 110k. I have a problem with losing coolant. I had the heater core replaced a couple months ago. I had it pressure tested and full of coolant 2 weeks ago and now the tank is empty today. Pressure test held pressure and they cant find a leak. Any idea what this could be?

 

are you looking under the radiator cap .. or just the reserve bottle...

return to where you had it serviced and have them retest it...

NO guessing..

 

They are testing it at the tank

 

If you are not leaking eexternally then you are leaking internall.

 

No white smoke and I can't smell it burning

 

check the rubber connection tube between the radiator cap and the overflow tank, if there is any splits or holes in this hose, you will also lose system coolant as the engine heats up, and expels coolant, and cools off and pulls coolant back in.

 

There's two heater hose lines that run down the left side of the engine (if you're looking at it from the front). The lower one is a two piece with a factory coupler in the middle. I was dealing with a loss of coolant for a long while out the overflow until I discovered that at the connection there were signs of coolant escaping. This would allow air into the cooling system, which was over pressurizing the system, purging coolant out the overflow.

Just something cheap and quick to look at.

 

What did you do to fix yours replace entire hose with coupler or just coupler.