I'm looking at an 08 6.4L that is in really good shape, but does have 205k on it. The only thing that jumped out at me and had me concerned is that the fuel coolant cap is missing, and the reservoir is dry. It appears to have been gone for some time. Is this something on the 6.4's that should raise a concern, or would I just be looking at replacing the pump, and all is good. If that is all it is, and I can use it as a negotiation tool without having to worry about major issues, then the truck would be a great investment. Any info would greatly be appreciated.

 

the cooling system is designed to run at 16PSI max. Increasing the PSI of the cooling system allows the boiling point of coolant to be higher...which provideds greater protection.

now...why is there no cap on the degas bottle....only 1 reason...under pressure the cooling system could leak at water pump seals and oring connections if those seals and connections are defective...by removing the cap...you have zero PSI and it will help prevent coolant loss thru the leak points. to include egr leaks , which would be serious.

this is a run and do not buy senerio....any 6.x diesel that has a coolant problem such as this and is now for sale...is likely to have been over heated which could result in head gasket problems, cracks in the cylinders, etc.

pass on it.

 

2 separate systems. Fill it with 50/50 Ford gold and get a cap.