working on a '97 1/2t 4x4 with a 360 and automatic.

for the past 3 mths i have (3) times had to add coolant to the overflow tank to bring it from "add" to "full". we're talking around 1/2 gal or less antifreeze. everytime i pull the rad cap cold the coolant is topped off.

when i start the truck and take off, under the dash i hear what sounds like coolant flowing thru the heater core and lines. the heater works just toasty.

i have checked the floor and under the mat, no leak. I have pulled the trans dipstick thinking mebbe its leaking thru the tranny cooler in the rad, no coolant in the trans fluid. I have pulled the engine dipstick, no coolant and no sweet taste in the oil...nothing leaking on the ground.

no loss in engine power, no white tailpipe smoke so no indication its burning it...where the heck is the coolant going and why does the heater core always sound like its, for the lack of a better term, 'refilling itself and the lines" everytime i start to drive away after startup?

anyone esle experienced this?

thanks guys!!

 

Air in the heater core is a very common problem. Try searching the forum for "burp" and you'll find the collected wisdom on the subject.

 

dude, you 'tasted' the oil!! You're alright in my book!!

I just burped mine Saturday... I thought I had before, but apparently I didn't get all of it.. Its difficult to purge all the air out of these things is the point I'm trying to make.. My heat was decent, but not really hot- it's really dang hot now, as in hotter than it's ever been.

Even with the front of the truck elevated (running, heat cranked- defrost wide open and rad cap off) it took an entire hour before bubbles stopped appearing- and a half gallon of antifreeze.. I would never have thought there was that much air in there, but there was.

 

Now that it's too late to do you any good on this go-round: I've had the best luck by using the tuner to set the idle to 1200RPM while burping the cooling system. I've got to flush my heater core soon, but there's no air in the darn thing now.

 

thanks unregistereduser, i went back and found ur reply on making the pass side higher than the drivers side, like on a hill to burp it.

i hadn't done anything to cause this but i rememebre the guy i bought it from saying they replaced the rad not too long ago so thats prolly y it happened...

again thanks all...

and yes, just a dab on the tongue of the oil yells if it has a sweet taste...old school trick, lol.