I think I'm going to change out the coolant on a 99 chevy suburban w/ a 454 this weekend, but this is really a general question on something I've never really been sure of. In a standard open cooling system (i.e. the overflow tank is not pressurized/has a vent on its cap) and in the absence of special bleeder valves, how do you effectively bleed a cooling system?
I've done this to two cars previously. The 93 volvo has a closed system with a pressurized expansion tank. The thermostat housing has a bleeder hose coming out the top. Air bubbles are forced up through that hose into the expansion tank, forcing the coolant level down. In that car I just had to top it up a couple times and then the level remained constant. The 83 280zx had an open system and no bleeder valve that I knew about. IIRC all I did with that car was check the radiator level and expansion tank level after driving it a couple of times and just had to top it up a little. At the time I didn't know that bleeding the system was a requirement, but everything turned out fine.
I'm not really clear on what I have to do with this chevy. It's got an unpressurized expansion tank and a pressurized radiator cap. Is it sufficient to just leave the cap loose ("vent" position) and run the engine until it hits operating temperature? Seems like any air bubbles would get pumped through the system and come out the top when the thermostat opens up.
In any case it seems like there are going to be air bubbles stuck in the system until the thermostat opens up in the absence of a bleeder valve on the engine. Is this not a big deal?
I've done this to two cars previously. The 93 volvo has a closed system with a pressurized expansion tank. The thermostat housing has a bleeder hose coming out the top. Air bubbles are forced up through that hose into the expansion tank, forcing the coolant level down. In that car I just had to top it up a couple times and then the level remained constant. The 83 280zx had an open system and no bleeder valve that I knew about. IIRC all I did with that car was check the radiator level and expansion tank level after driving it a couple of times and just had to top it up a little. At the time I didn't know that bleeding the system was a requirement, but everything turned out fine.
I'm not really clear on what I have to do with this chevy. It's got an unpressurized expansion tank and a pressurized radiator cap. Is it sufficient to just leave the cap loose ("vent" position) and run the engine until it hits operating temperature? Seems like any air bubbles would get pumped through the system and come out the top when the thermostat opens up.
In any case it seems like there are going to be air bubbles stuck in the system until the thermostat opens up in the absence of a bleeder valve on the engine. Is this not a big deal?
