172 Ford diesel fuel in oil

Forum Members,
Another issue-
I have been working on a 172 Ford diesel off and on for the past few years. Engine runs fine but I have an issue with fuel draining into the oil pan. I thought I had figured out the problem but when up north last there was too much oil/fuel in the oil pan. Problem is this is happening when the engine is not running. This engine is on an old Pettibone log skidder with two lines coming from the gravity fed fuel tank. The lines exit the tank one in the front and one in the back which I believe is to accommodate for going up and down rough terrain to get a constant fuel feed. One line has a shut off valve and the other does not. Could it be that the valveless line is allowing fuel to somehow go through the injector pump into the oil pan? Is there a problem with the injector pump seals? I plan to put a shut off valve on the valveless line to see if that cures the problem.
One more observation is that the injector pump is always very shiny, glossy looking on the outside as if just spit shined??
Any and all comments are welcome.
 
Pump might need repair, if the retainer is breaking apart inside the small bits will cause the drive shaft seals to leak. I repair 3-4 pumps a month in for this problem. There can also be leaks at the injector return allowing fuel into oil as injectors are under the valve cover.
 

Pump seals is probably leaking like Dieseltech say's.
The line with the shutoff valve is the supply line for fuel going to the pump, the in at the front of the tank with no shutoff is the return line for excess fuel returning from the pump and injectors.
Normally that tank fitting has a stand pipe inside to prevent fuel from leaking back but often with age they get broken off, doesn't hurt if the stand pipe get broke off other than there's no way to keep the fuel from draining the tank if you disconnect the lines other than plugging the line or draining the tank.
Stand pipe on my 801 has been broke for many years.

My best advice is remove the pump and have it gone thru, staying shiny tells me some of the other seals are weeping fuel and will become leakers.
Replaced the umbrella seal in mine, then the throttle shaft seal started leaking, fixed that, then the head to body seal leaked.
Tractors not needed now and is setting but next time the pump comes off it's getting a full rebuild.
 
I will follow your advice and remove the injector pump and have it rebuilt. I have a replacement pump to install that has been rebuilt and hope it cures the problem. In addition to the fore mentioned situation this engine is different from the original. The engine is a match but has some differences as far as it fuel injection circuit. I am going to check to see if there is a standup tube located at the front line coming from the fuel tank. That particular line is not attached to the return elbow on the pump. If that is a return line I will reconnect to the fuel tanks front port. There is also a very small line 1/16 inch that travels from the block to the tank. I have removed and cleaned that stand up tube. Do/did these engines have two return lines to the fuel tank? I am a novice and welcome any and all info. Also this machine is located 170 miles from home. Thanks again for the help!
 

On ag models the inj pump and inj return lines tee'd together going to one tank return, not sure how all of the industrials are plumbed, but even the industrial engines we have only have one fuel supply line.
 

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