I have a 96 K3500 crew dually and it uses about a quart of coolant every 150 miles.There are no puddles of coolant were I park, it has good power, no bubbles in the coolant bottle or steam from the exhauste I.E. none of the normal blown head gasket indicators. Any ideas about what is causing this.

 

look around heater hose near T-Stat they like leak and from the heat you won't see the coolant

 

O.K. thank you I might just replace the hose to elemenate it as a possible cause.

 

My first truck was an 83' 6.2 diesel and it had the same problems. It would run fine but towards the end it was using about 1 gallon of coolant/day. It turned out to be a cracked block/head, can't remember which right now long time ago.

 

80's diff set up from the 90's

 

Turns out this was the water pump it was leaking from the lower weap hole and I could not see it. The pump started to sqeak and the leak turned in to a steady flow when the system was topped off.