I have a 2006 6.0 with now about 285,000 miles. about a year ago i had a crack in the top of the radiator and lost coolant. replaced that. about two months ago i noticed a crack in the degass bottle. replaced it. now i'm loosing coolant again.

if i fill to the bottom of the sticker it seems within 1000 miles i'm adding another gallon. a little is blowing out the cap but i'm not sure thats from filling back up. if i let it idle for 30min there is no water under the truck. also the oil level is normal. no white smoke. i deleted the egr about 100,000 miles ago and the truck has run great ever since then. any thoughts?

 

Wow you've got a lot of miles on your truck, I'll be thrilled to make it to 250k some day.

I went through this coolant loss business a while ago. It can be a real pain. Seems to always find the weakest link. You replace one thing and something else leaks...

When you replaced the degas bottle, I'm guessing it came with a new cap. If it's not holding pressure it can affect coolant levels. Might be a cheap fix to just replace the cap since they're pretty cheap. Also, clean the bottle and cap really good so you are 100% sure there's no leaks there.

Are you sure there are no leaks anywhere? No residue around the degas cap? How about the hoses? Also check the water pump pulley and belt tensioner.

There is a writeup in the tech pages on coolant loss, helped me a lot
https://www.ford-trucks.com/forums/1...nts-degas.html