Gurgling heater core 5.3 Silverado

I have a 2000 Silverado with the 5.3L engine with 178,000 mi. The problem I having is a gurgling noise from the heater core at startup, before the engine reaches operating temperature. There is some loss of antifreze about one Pint a week or so.

there no coolent in the oil, no coolent smoke or smell from the tail pipe, no smell of antifreez in cab from heater core, no signs of leeks.
Are,these two problems related???
Truck runs great no other issues.

Any ideas on the problems?

Thanks

I have a 2000 Silverado with the 5.3L engine with 178,000 mi. The problem I having is a gurgling noise from the heater core at startup, before the engine reaches operating temperature. There is some loss of antifreze about one Pint a week or so.

there no coolent in the oil, no coolent smoke or smell from the tail pipe, no smell of antifreez in cab from heater core, no signs of leeks.
Are,these two problems related???
Truck runs great no other issues.

Any ideas on the problems?

Thanks

Yes, if the coolant level drops your heater core may gurgle, as for the low level, put a pressure tester on it, with that kind of mileage I bet your water pump seal is weeping. Do you have any "gunk" in your cooling system? If the heater core is sludged up it can do this too.

I have a 2000 Silverado with the 5.3L engine with 178,000 mi. The problem I having is a gurgling noise from the heater core at startup, before the engine reaches operating temperature. There is some loss of antifreze about one Pint a week or so.

there no coolent in the oil, no coolent smoke or smell from the tail pipe, no smell of antifreez in cab from heater core, no signs of leeks.
Are,these two problems related???
Truck runs great no other issues.

Any ideas on the problems?

Thanks

these engines are prone to corrosion when dexcool is not used with distilled water ..you need at least 50% dexcool...

the water pump gasket/engine area leak is well known...this is as you described a leak that is somehow not revealing its self...

any loss of coolant is serious with this system..the leak will indeed cause this noise heard in the cab.

with this setup you must fill the coolant while the engine is running with the coolant cap off or air will be trapped.

the reason it leaks at these gaskets is because of the corroded metal...

like J cat said, check where your water pump mounts to your block. I had the same problem with my 6.0L it was the passenger side gasket leaking. You can get just the gasket kit but if i was you and had the same amount of mileage that you do i would just replace the water pump while i was in there(just to cover your a** in the long run). The leak was very small on my truck and was drying up before it had a chance to hit the ground. Hope this helps.

I will check the water pump again for seepage, i should just replace before it's zero out.
Also with the fluid level full, Im still getting the gurgling sound, how do i go about bleeding the system? do i drive with cap loose to help remove the air.

Thanks

I will check the water pump again for seepage, i should just replace before it's zero out.
Also with the fluid level full, Im still getting the gurgling sound, how do i go about bleeding the system? do i drive with cap loose to help remove the air.

Thanks

the bleeding proceedure is as I stated before...remove the coolant cap, start engine continue to run and add fluid until the engine is at operating temp ...rev the engine a few times to 2000rpm ...heater on MAX..then put coolant cap back on..

the bleeding proceedure is as I stated before...remove the coolant cap, start engine continue to run and add fluid until the engine is at operating temp ...rev the engine a few times to 2000rpm ...heater on MAX..then put coolant cap back on..
Thanks for your help!