The heater has lacked last few winters and in SoCal this was not really an issue until lately!! The normal temp of engine seems fine but heater lacks OEM HEAT status. Admit to only changing fluid about 5 times over 11 years. I started to hear a sound like a small stream dripping into a metal bucket or something coming from under the dash on pass side and figured the core was getting plugged on the entrance. Or maybe the bypass control for heater hoses had become clogged. Put a qt of Prestone super flush in it and have about 3 hours dive time on it via work commute. Plan to drain and flush over the weekend. Anyone with history and resolution similar/same. Would be great to hear the details. TIA
Bob

 

Probably an air bubble in the heater core.....

There is no flow control valve for the heater core, it always has flow.

Burping the cooling systems on these trucks seems to be a real chore for a lot of folks. Me being among them.....

 

don't forget that an '02 is a hybrid between second and third gen, with components from both series on them..

the early build third gen's had issues with blend doors.. that particular component is on an '02...

that said, the dripping sound absolutely indicates either a leaking heater core or a nice big ol' bubble hiding out in there.

 

Any tips on Burping method/s ? Thanks for the heads up. It did somehow run out of water once and heated up. Caught it right away, refilled after cooling down. Never seen it go low since. Wonder if the heater core took on a bubble at that time ? Going to drain and flush in the AM.