i posted a while back about a coolant leak i was having(couldnt find the thread), i thought through the exhaust. the low coolant light came on again today, so its definitely going somewhere. about 300 miles from fill to low coolant .ive had the heads pressure tested for cracks, and they were resurfaced before reinstallation, felpro gasket set....nothing visible externally as far as leakage. its not in the oil. anyone have any insight they could lend... would be much appreciated

 

Heater core could be leaking is your floor board wet it might also go out the ac condensation tube just a idea since sounds like every gaskets has been changed

 

its not the heater core, ive gone through that.i guess i should mention its a 99 4.8 with 34" radiator

 

My 00 Sierra w/4.8 did the same thing and the light always seemed to come on in the same exact spot on the way home and it ended up being the weep hole on the water pump. Not sure if it's any help but a suggestion I guess.

 

or check the cross over tube, could have slight leak in one of the corners

 

I went thru the same thing for a few years. I replaced the radiator, water pump, thermo, and all the hose's and heater core (3)times. I had my heads milled and tested. I would have to add 16 ounces every 50 miles. My first problems it was busting heater cores. It would pop one every 6 to 9 months. I changed the filler cap (it was bad) and it started blowing the water out the over fill jug. I have never been able to put a finger on why but I swapped my heads out with new and no water lose at all. not one drop has been needed in 6 months. I guess there was a crack in one head only when really hot and pressuring up the cooling system. I took it to several shops and no one could find a problem. We would pressure the system up and nothing would be found. it was strange but fixed now.

 

Check front engine cover and oil pan for orange streaks and stains. Water pump seals or pump itself could be leaking.

 

i have replaced the crossover tube already. heres a vid i said id postMVI_0690[1] - YouTube its a cold start, you can see either condensation or coolant dripping from the pipes

 

****, wrong video

 

http://http://www.youtube.com/watch?...&feature=g-upl