anti freeze use

[jim5722]

Hi everyone this is my first post.
I have an 2001 LBZ which started using antifreeze at the rate of about a quart a week (400-500 miles) no apparent leaks,cap is new dealer is searching but no answer yet. Truck has 170000 all maintenance runs great, although had oil filter and fuel filter changed a few days ago and the truck was incredibly slow to accelerate omto expressway. Thought maybe it had a bit of air in it from changing the fuel filter. Any thought

[Quack_Addict]

Welcome to the board!

Sorry to disappoint, your truck has the "LB7" Duramax, not the LBZ.

There's normally 2 places antifreeze goes when you don't see a leak... through a bad head gasket and out the exhaust (white smoke) or through your heater core (sweet smell inside the cab). Does your heat still work in the truck? Do you hear any gurgling sounds coming from under the dash after you shut the truck off with the engine up to operating temperature?

[jim5722]

Not leaking thru heater. dealer says it holds 23lbs of pressure for 4 hours.
no smoke (but I believe the turbo would probably take care of the white smoke from the moisture) no leaks,.
Thanks for your thoughts and keep thinking,
Jim
This is my daughters truck to pull her horse trailer it is the LB7 my 2006 is the LBZ guess I was sleepy!

[beeler]

Take a good look under the water pump. When mine was new it lost coolant. Finally found prove of a leak under pump. It was leaking out of weep hole but not enough to hit the ground.

[jim5722]

Thanks Beeler
We've done that once I picked the truck up with a forklift and pressure washed it and let it run for 4 hours with no apparent leakage. But you've got me thinking so I'll take another look.
Thanks again
Jim