Detroit 14l- missing coolant!

Did you test you radiator cap? Pressure test the cooling system? Any coolant getting in your fuel tanks or fuel in the coolant? Do you have a trans cooler that could let coolant in the trans? Better check that to be safe too.

 

I recently had that same issue with my 03 Columbia. You should do a block test on the coolant system. I found that I was having combustion gases pushing into coolant system and out through the blow down tube on the reservoir

 

The additional combustion pressure will cause your cap to relieve the pressure and therefore lower your cooling efficiency

 

Start with the radiator cap. I would pressure check the system to eliminate a head gasket issue. You can get a pressure check kit at Napa pretty cheap.

Check to see if you're getting heat to your heater core. If no heat, check the water pump.

 

I have had a couple of instances where I was losing fluid and could not see where it was leaking. One was a leaking hose that ran from the front of the engine to the sleeper. The hose was leaking right over the engine and the water evaporated immediately when it hit the engine. It finally got bad enough where the leak was obvious. More recently, I was in west Texas and had to add 4 gallons of water. Again, I did not see where water or antifreeze was leaking on the ground. I finally found the leak. It was the heater core under the sleeper. The water was leaking on the exhaust and immediately evaporated. I had a shut off valve installed to get home and to my mechanic. You may also check your fan clutch for leaks and to make sure it is working properly. If air is escaping your fan won't operate properly and will allow the engine to over heat. Sometimes it can be a real challenge to find a water leak.

 

Did the new coolant tank not come with a new cap? Either way the cap is a cheap first try.

Oh, I just saw the picture. Never mind......

 

Looks like that could be the issue. There should be dried water marks all over everything behind it. If it's an outside leak it's not much of a mystery where it's coming from. There will be white marks from dried antifreeze over everything around it.