So after a distilled water flush with thermostat out and then putting in ELC, I kind of expected that there would be some burps and bubbles to get rid of and I'd see the level drop in the degas tank. But, after driving over the weekend and having to put in a quart of distilled water to get it just below the MIN line, I thought I'd be good. Not so. Drove it to work 2 days and it's now a half inch below the MIN line. Not sure if this is the normal level, but the truck has been losing some coolant over the last year. The first time I noticed it was when my daughter returned from trailering 4,000 miles and the tank was empty. Took about 3/4 quart.

I found a pin-hole leak in the lower radiator hose and replaced both that and the upper hose as well as the thermostat and the degas cap. It holds pressure for over an hour after shutdown when hot. I can see no weeping or evidence of leaks. Oil is clean and the level is not increasing. There is no steam or white smoke. Pressure test?

 

One of my leaks was in the Heater core , take out the contents of the Glove box pull the tray and heater cover , Now you have to decipher if it's condensation or coolant( taste test ) the Other places to look is heater control arm the screw on the top has been known to leak, also the hose that wraps around the FICM mine had been rubbing on the lower peg so I taped it and wired the hose off the ficm.

 

That's interesting because after I put the new t-stat in, it was kind of cool the next day and I ran with the heat on. Had to crank the temp up to 76 before it even became comfortable (and that was with AC off). Will definitely check all of them. Where is the heater control arm? The truck has buttons - no levers.

 

heat control arm is on the passenger side 2'' round black plastic with a metal swing arm the screw is in the center that hose goes to the core