My 04 tahoe leaks coolant from somewhere only when reservoir is full when it drains out onto the ground, it stops when it gets to the bottom of the reservoir where you can still see the coolant. It doesent overheat but it doesent produce heat when just running it has to be driving. I tried to find the radiator to poor coolant directly in the radiator but i dont know where the cap for it is!? My mechanic is away until next week. Need help!

 

I suspect since the coolant is draining out of your reservoir, that means the coolant in the cooling system is going into the engine somewhere and either being burned or filling up the crankcase. Check the underneath side of the fill cap to see if there is any gray jelly looking oil on it. Also check the oil level on the dipstick to see if it's above normal.

 

Chev stopped putting radiator caps on radiators. You fill the top of the plastic reservoir. Aside from the advice above, look for any obvious cracks in the reservoir or leaking hoses as well.

SD

 

Thanks both of you guys