98 1/2 ton coolant loss

[tommyrs33]

Hello.

This is my first time here. My fiance has a 98 GMC 1/2 ton (Sierra) with the Vortec V6. For some reason her truck is eating coolant. It doesn't leak, it doesn't blow smoke but coolant is disappearing. The only thing that is odd is when we take off from a stop, there is a gurgling noise that comes from the passenger side dash. The floor is dry and I am just stumped.I am asking you guys for her as I am a Ford boy and don't know much about GMC.

 

Anybody have an idea???

 

Thanks for any help given in advance.

Tommy

[GM-Tech]

The noise is from the heater core and is due to air in the system. Find and fix the leak and get a full cooling system and that will go away.

 

If you're absolutely sure it's not leaking externally, then it must be internal. Could be an intake, head/gasket, cracked block, etc. Look at the oil fill cap underside. Is there condensation on it? If so, coolant is going into the oil and it's probably the intake.