I have a 2005 Dodge Ram 1500 4x4 Crew Cab HEMI with 103000 miles. In the past 3 weeks it has used 1.5 gallons of antifreeze. I cannot see any leaks anywhere in the radiator or the hoses. There are no puddles of fluid under the truck after driving it and the engine is warm. The oil is normal color. Engine runs normally with fluid kept at normal level.

Someone suggested the water pump may have a weep hole and that's where the fluid is escaping. This problem started all of a sudden and I noticed it when my light came on telling me to check the gauges and my truck started running hot. I pulled over and the antifreeze jug was low so I filled it back up. I have had to top it off because it keeps going down but I cannot see a leak.

Any ideas?

I haven't tried the dye but that's next.

 

Water pump failed probably.

 

Same thing happened to mine. I also would smell antifreeze. It was the waterpump. replaced at 70K.

 

replace or test the radiator cap..

have the cooling system PRESSURE tested..

if anti-freeze is leaking from the water pump seals or weep hole.. it would be on the Floor.... drops or a puddle...

do not replace parts by guessing.. most guesses are wrong/incorrect...

 

You can also do a block test. This will tell if there are hydrocarbons present. Possible head gasket. I would do a compression check to make sure.

 

1.5 gallons is a lot to use without seeing anything, I'd suggest having it pressure tested to pinpoint the leak. Alternately, you could search for the leak when the truck is hot, after a long drive, it should be under pressure then.
I've seen some water pumps, but more often it has been the rad. Look close with a flashlight at the top corners of the rad where it meets the plastic tanks. You should be able to smell it too, it will smell sweet.

 

Drove 500 miles round trip yesterday. Reservoir did not go down and no visible leaks but I could smell it. I drove for a couple of hundred miles and pulled off to check it. Upper hose was hot as expected but lower hose was cold. It appears the water wasn't circulating but it didn't over heat either. I brought extra fluid just in case but it never went down.

Scratching my head?

 

Got a blockage somewhere then, most likely the rad, should be overheating.

 

Just put the pressure tester on it. Pumped up to 16psi and antifreeze immediately starts dripping from the bottom of the water pump housing. Dam it! Why couldn't it just be a bad cap?

If I have to replace the pump I may as well replace the serpentine belt, thermostat and radiator cap.

 

that is what I would do. and your luck is like mine.