I filled my coolant yesterday after driving to the "max" line. Today when I awoke it was right at the "min" line. I didn't see any noticeable liquid below the truck, except under each front fender but I think this was water from the dew evaporating/condensing and running off the truck. Any ideas on what happened to the coolant or did it just cool down and condense. It got pretty cool last night (mid 40s). If it helps I have an 02 f250 5.4L

I feel like there is a leak somewhere, does anyone have a link to or a procedure they can explain for finding it?

 

When its cool the coolant level will be lower. I would check the oil for coolant though just to rule out a head gasket.

 

It will shrink quite a bit when cool vs hot. When in doubt, pressure test it.

 

thx, how do you check the oil for coolant?

 

Check the oil’s color. If it’s brown or black, that’s fine. But if it has a light, milky appearance, this could mean coolant is leaking into the engine.

 

On the dipstick the oil looked fine. It was however high, however, I didn't do the last oil change, so not sure if the shop put more than specified in. I also just drove and checked the coolant level again and now it is over the max, so I guess the heat from driving can really expand it.

 

It takes a "fill" or two to get the coolant level right, in my experience. The only way I remember to get it right the first time was to have the system open when filling, but that was more than a few years ago.

 

Having too much oil will wreak havoc with your motor. I don't know how much you're over but I would drain off enough oil so it's where it's supposed to be.

 

That is how the system works. Heat expands cold contracts. So when the engine heats up it expands and needs somewhere to go. When the motor starts to cool it will suck the coolant back into the radiator. Next time you drive it check to see if it is near the max line. NEVER NEVER NEVER open the radiator cap HOT. It is under pressure and blow 200 degree coolant all over you.

 

A qt or even two over full on oil in a 5.4 wont hurt anything except maybe a little performance. A gallon or more definitely not good. Make sure your not "making oil"...IG coolant is filling the crank case bringing up the oil level. It wont always be milky if its not mixed up good from daily driving. Keep an eye on it. If you need to keep adding coolant and the oil level is on the rise time for a PSI check and to drop the oil to see what comes out of the pan. Your likely OK. Sounds like standard thermal expansion/contraction.

 

Read online you can check for coolant in the oil by draining some into a clear cup. The coolant/water is heavier than oil so you will either see some clear or white ar the bottom. I drained about a pint and didn't see anything so I'm thinking it's just thermal expansion. Anyways thx for the help