diesel fuel in oil pan on 172 ford industrial diesel

[Mr. T. Minnesota]

Forum,
I have an old Pettibone log skidder with a Ford 172 industrial diesel engine in it. Started it this week and noticed the oil pressure not as it should be? Figured out there was a lot of fuel in the oil pan. Question is how did the fuel get into the oil pan? There are a couple of possible reasons.
1. Could leaving the fuel shut off open let fuel through the pump?
2. Could the injector pump have a bad seal between the injector pump and the oil pan? The injector pump is the distributor type.
3. Could the in and out lines to and from the injector pump not be set up as they should be? By this I mean the (in line) to the pump is ok but the outlet side(return line) of the injector has a plug in it. Will this make a difference?
4. One last hitch- it is a gravity type set up but has an electric fuel pump in the system. The fuel pump was in the unit when I bought it so I kept it in the system.
Any and all help is appreciated.
Mr. T. Minnesota

 

[Bern]

No on #1. Yes on #2. Partial yes on #3. I suppose if the fuel return line is plugged it could elevate the internal pressures in the pump and force fuel past the driveshaft seal.

Another good possibility is a leaking injector return line on top of the injectors. This is under the rocker cover, so if it leaks, you've got fuel in the oil.

 

[Dean]

I would bet on Bern's last paragraph. This is not uncommon on these engines.

Pull the rocker arm cover and inspect.

Dean

 

[riveroadrat]

I think he meant injector pump. I would replace the pump driveshaft seals first. You arent using a galvanized fuel can are you?

 

[Dieseltech]

On my 861 after repairing the pump it still had fuel getting into the oil. Found the injector return line packing nut loose in top of the head. In most cases it's usually the injection pump though.

 

[Mr. T. Minnesota]

(quoted from post at 00:13:36 12/02/18) No on #1. Yes on #2. Partial yes on #3. I suppose if the fuel return line is plugged it could elevate the internal pressures in the pump and force fuel past the driveshaft seal.

Another good possibility is a leaking injector return line on top of the injectors. This is under the rocker cover, so if it leaks, you've got fuel in the oil.

Is the injector return line the very small line that comes out of the block and returns to the fuel tank? Fluid does flow through that line.

 

[Mr. T. Minnesota]

Where does one find these seals?

 

[Dean]

CNH.

Dean

 

[Bern]

The injector return line is #37 in the link below. It is under the rocker cover, you cannot see it.
Return line

 

[Mr. T. Minnesota]

Thanks for all of the possibilities for a solution for the fuel to oil pan problem.
I am going to replace the seals on the system. One suggested the pump outlet was plugged to gain pressure. I will remove the plug and reconnect it to the return line to the tank as it should be and keep the electric pump. From there just hope it works! Will give an update when the snow melts this spring.
Will also check the injector return line.
Thanks again

 

[Al Baker(pumpman)]

9 times out of ten the injection pump drive seals are leaking. This pump stands upright and has fuel head pressure on the seals even when not running. There is a o ring on this style drive shaft that is there to help , but it is common for these to leak. Almost always the ford style 172 pumps have a steel pilot tube so a grove worn in the tube shouldn't be a problem. I have seen the return fuel tubes under the valve cover crack. I have seen them just need to be snugged up a little to seal the copper washers. Al

 

[Mr. T. Minnesota]

(quoted from post at 01:47:56 12/03/18) 9 times out of ten the injection pump drive seals are leaking. This pump stands upright and has fuel head pressure on the seals even when not running. There is a o ring on this style drive shaft that is there to help , but it is common for these to leak. Almost always the ford style 172 pumps have a steel pilot tube so a grove worn in the tube shouldn't be a problem. I have seen the return fuel tubes under the valve cover crack. I have seen them just need to be snugged up a little to seal the copper washers. Al

Thanks for the info. Is it easy to replace the seal/seals on this Roosa pump. If so, could you give me some tips. I have never done work on an injector pump, just a lot of carbs.
Thanks again.