Diesel in the Oil Problem in Ford Engine on Trawler

[Panamajames]

My friend has a 38' trawler about 25-30 years old with a Ford Diesel engine. He recently had it rebuilt and now about 20 hours later he noticed his oil level going up. He quickly realized that diesel fuel was getting into the oil. How does this happen? Thanks for any information you can provide.

[DeepFrz]

Could be the diaphragm in the mechanical fuel pump. Hopefully that is what is causing it. Otherwise it would be a seal in the high pressure pump.

[NoTies]

Most likely the fuel return pipe under the rocker cover. These are prone to fracture on the Fords and the line should be led back to the tank, rather than recirculated back through the filter to reduce pump pulse.