# Diesel fuel in motor oil



## dragonrb44 (May 27, 2014)

My 64 ford 4000, 4cyl has diesel fuel in the motor oil. When I the checked oil I was surprised to fine how clear it was, and 1" over the full mark. Oil is very thin, so pretty confident that fuel is going into the oil. Question is how it is getting in. Durning the winter, tractor stalled when fuel froze because of no additive. I am thinking maybe I messed up one of the O rings on an injector. I have never had one of these injectors out to inspect, but I understand there is an O ring. I remember turning one of the injectors in the block because the fuel line was so tight that the injector turned instead of the line connection nut.
I also removed the pump from the base of the tractor. Don't remember if there was an O ring on the injector shaft that fits down in the tractor. Just another consideration. I am just a jack leg mechanic, so looking for ideas.


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## Big_T (Dec 1, 2011)

Hello dragonrb44,

Welcome aboard the Ford/New Holland tractor forum.

See attached parts diagrams for your injection system and injection pump. Since you messed with an injector, the most likely source of the leak is from this injector; however, there is a diesel return line inside the valve cover that is also a common source of leaks. I copied the following comment on the internet written by *John Bud* regarding this return line. John is an expert on these old Ford tractors.

*"You can check for the return line leakage by taking off the rocker arm cover (it does come off, but it is tight!) and inspecting the line that goes from each injector to a down line in the head. They crack around the solder joints especially by the injector."*

You may have to run the engine with the valve cover off to see fuel leakage; however, if the fuel standpipe (item #47 in diesel fuel system diagram) is broken off, leakage will occur with the engine off. 

NOTE: There are two small washers with each return line connection. Take care not to LOSE them down the pushrod holes.

If you see no leakage on the fuel return line, then pull the injectors and take them to a diesel shop and have them tested.

If all of the above checks out, then turn your attention to the injection pump. Quoting *John Bud *again:

*"The other source of leakage is the 2 umbrella seals and one O-ring on the pump drive shaft that goes inside the pump from the bottom. You have to pull the pump to change them. Nothing too tricky there, you just have to set time before pulling the pump (23 degrees before TDC) and be careful to not pinch or roll the first umbrella seal as it is intalled."*


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## dragonrb44 (May 27, 2014)

This is great information. The parts diagrams are going to be very helpful.

Thanks,

Dragonrb44


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