Cooling system not holding pressure

[Weirdguy]

Truck:

2006 Sierra with a 5.3

Issue:

Cooling system does not hold pressure

Steps taken to fix problem:

New thermostat

Bled air from system

Taken to stealership, only for them to claim it was "normal"

[Hambone!]

Did anyone start with the simple stuff, like checking the pressure cap? Is there a visible coolant leak? Smell? How could a thermostat contribute to the system not holding pressure? Hope the Stealer didn't charge anything.

[decibles]

I hate to ask stupid questions but how do you know it isn't holding pressure are you using a pressure pump which goes in place of the cap. Perhaps you are going by the pressure after warming up. You haven't given us much to work with here. I assume you have verified that pressure is being lost not being cancelled by contraction from cooling. I will be glad to help if in fact you have confirmed the loss of pressure. The thing about cooling systems which lose pressure they show up pretty easily by doing a pressure test with a known good test set.

shane

[Hambone!]

Methinx this thread....is ded.