Recently I have been noticing my coolant level has been dropping. The tank is empty at least once a week, I drive 75 miles a day at most. There were spray patterns around the reservoir cap so I changed that but no help. So I replaced the tank, thermostat, all the hoses in that area, and flushed the system but still no change. I still get spray pattern and still lose coolant at the same rate. Does anybody have any ideas as to what might be causing this, it seems there must be a block in the system somewhere. The truck has approx. 85000 miles and does no run hot or show any signs of a bad cooling system. Any help is appreciated, I want to get this fixed.

 

Sounds like you could have a bad head gasket allowing cylinder pressure to enter the cooling journals. Is there any grayish residue in your overflow tank?

 

I have not noticed a grayish residue but the coolant looks like a rusty color.

 

Hmmm. Have you checked it right after a WOT run? Thats usually when it'll spray out of the reservoir if it's a head gasket.

 

I will check that later today, thanks for the info.

 

WHICH coolant Tank?

I notice you have a '99 Lightning, is it the Intercooler Tank, If so, I'm sorry to break this to you. $$$$$$

Read here:

https://www.f150online.com/forums/sh...hreadid=174350

 

It is the engine coolant not the intercooler tank.

 

im thinking head gasket.