bad plumbing?

[hump]

OK, I start my truck in the morning and let it idle. When I step on the pedal to get moving, I hear a "whooshing " sound like water running through a pipe for a few seconds, coming from behind the glove box. Is this normal with the first surge of power for the day, or could it indicate air in the cooling system, which is supposedly bad with dex-cool? Just wondering. Also, any idea why front brakes grab only while in 4x4?

[gmctd]

Rushing noise from the heater core usually means the coolant level is low in the radiator.
Check it on level ground, cold.

Front brakes have individual tone wheels for ABS input, rear is single output from the VSSB.
Check all connectors first, and inspect the tone wheel and pickup for each front wheel.

[hump]

Thanks gmctd, I checked coolant in tank, it is about 1/2 inch below cold mark. Doesn't seem like much to me but I guess I can top it off. As for the brakes, the ABS light has been on since I bought it (Oct) and I'm not inclined to fix it! (not a fan of GM ABS) I just wondered if it could be mechanical.

[gmctd]

Also check coolant level in radiator - overflow tank is not always representative of actual coolant level.

Try R&R'ing the ABS connectors, starting at the wheels, working up to the Computer - sometimes, that's the cure.