Chevrolet Repair: 89 Chev C2500 PU Losing Coolant, head gasket problem, losing coolant

Question
Our old Chev PU is losing coolant when driven.  We have seen no puddles beneath the vehicle, there is no white smoke coming from exhaust, no wet spots on hoses/radiator, no coolant in the oil, no oil in the coolant . . . yet it will lose as much as 1 GALLON of coolant over an 8 mile distance.  Any idea what is going on??  The truck runs smooth as glass and has no other issues, but this is driving us crazy!!

Thanks in advance for any help you can offer.

Answer
Hi Clarissa... sounds like a head gasket problem.... if you have coolent leaking into several cyls at the same time it will burn off when driving, leak maybe not bad enough yet to show white smoke. if you want to see if that is what it is there is a dye you can buy at a parts store that you add to the coolent, run the truck then pull out the plugs and see if they have dye on them... if not on the plugs if you use a black light in the dark the dye will show where ever you have a leak....hope this helps