I have a 2001 F250 V10, every since I have gotten this truck back in 2003 the coolant level has never been able to stay at the max line. Whenever I top it off and I go back and check on it in a few days it has fallen down just below the minimum line and stays there. I have not noticed any odd puddles under the truck or anything. It does not seem to have any negative effects on the truck but I was just wondering if anyone else has had this problem?

The reason I am finally asking about this is because tonight I noticed it has dropped even lower (probably 1 inch below the min line). This weekend I took the truck out to Silverlake sand dunes and beat on it a little. Did 4 WOT pulls up a big hill at slow speed back to back. Everything seemed normal and I drove it home 2hrs today without issues. Could the rough ride and hard work by the engine have casued me to loose some coolant out of the overflow?

 

There is no overflow, the system is sealed and builds pressure. There are a lot of places where the coolant could be going, from a leak, to a bad heater core to a leaking head gasket and etc.

If you cannot find any leaks (make sure you look everywhere using a flashlight) then you could always pull the spark plugs one by one and see if there are any signs on the plugs of coolant in the cylinder. The plug would look a lot cleaner than the others.

 

Thanks dfk, I will look around and see if I see any leaking. I just don't understand why it would just leak a little bit and then stop. Like I said I never add coolant it just always stay right at the min line.

 

When the engine is fully up to operating temp, what's the level on the reservoir?

 

If I remember correctly it will go up to or above the max fill line when it is warmed up. I added some this morning so that it sits right in between the min and max fill line when cold. Drove about 2 miles to work and the level was about 1cm if not more above the max fill line when I got there. The engine was warmed up but idk if I would call it operating temp after just 2 miles.

 

Check your oil and make sure it's not milky. The engine oil cooler can leak internally, and let coolant INTO the oil, or oil INTO the coolant, depending on pressure and how it's leaking.

 

Oil looks clean and I don't see any oil in the coolant reservoir. It seems like a real mystery hopefully it will just drop back down just below the min like it always does and stay there.

 

I forgot about the oil cooler. A used oil analysis would tell you if you coolant contamination in your motor oil.

Also make sure your system is building pressure when hot. When up to opertating temp you can feel the upper radiator hose should be hot and hard.)I know, thats what she said) You can also crack the degas bottle cap when the system is up to operating temp to make sure it is building pressure.(put a heavy rap over the cap before opening it)

My dad an I both have V10s and if filled to the min line when it is cold, it will be up to or a hair under the max line when hot.

 

I will check those things dfk. Hopefully it will simply drop back to the min line and stay there like it normally does. I will keep you guys updated if I have more issues thanks for all the input!

 

Just wanted to update this thread, I believe I fixed the problem. Turns out my coolant cap was leaking. I looked around on this site and found someone that posted this video. After watching this I went out and got a new cap and it seems to have fixed the problem. Thanks again for all the help guys!