Diesel fuel in crankcase

Norm43

Member
I'm not familiar with these Ford diesels but I didn't think diesel could make its way into the crankcase like the gasers can. But ... Today is a very nice day so I started working in a 681 with the 144 ci diesel that I picked up last fall and found the dipstick clear full to the top. It looked very diluted so I pulled the drain plug and got about three gallons out of it.. When I bought it the oil level was right up on full so this seems to have happened since then. All I have done is turn it over by hand a few times.

So my question is can and how does the fuel get into the oil on this motor?

Thanks in advance for advice from the proven experts on this forum.

Norm43
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There are a few way it happens. If it has a fuel pump the pump diaphragm can go bad and let fuel right into the oil pan. Also the injector pump shaft seal can go bad and cause that. And the injector return line can have a problem and leak into the pan
 
My guess would be the injector pump is leaking into the crankcase. It's a gravity feed from the tank to filter and on to the injector pump, and if it filled the crankcase since you've gotten it and it hasn't been run during that time then the return line is probably not the culprit.

There's a seal on the shaft that drives the injection pump and that shaft goes right down into the engine like the distributor shaft on a gasser, so if that seal's leaking it would go right into the crankcase.
 
Years ago I got in an A/C XT190 that had a locked up engine due to diesel in the oil. Got it freed up and the problem was the shaft seal. This used a Rooster Master injection pump. Big work horse of a tractor but way to big for 44 acres of land
 
(quoted from post at 19:05:40 02/03/15) these tractors have return fuel lines under the valve cover that's where I'd look first.

He says that the oil level was correct when he got the tractor and that he's only turned the engine by hand a few times, so how would that much fuel get up into the return line?
 
Does the throttle shut off cut the fuel supply thereby stopping this situation? I guess I need to find a diagram of the pump and go from there.
 

As others have responded you have a leaking drive shaft seal but there are two of the seals on the drive shaft- not just one. They are "umbrella" shaped seals and one has the umbrella turned up and the other one is turned down. They are about $12 each at NH or you can buy a complete seal kit for about $35 on Fleabay.
 
(quoted from post at 21:05:38 02/03/15) Does the throttle shut off cut the fuel supply thereby stopping this situation? I guess I need to find a diagram of the pump and go from there.

I'm not sure about the throttle shut off, but the shut off valve up at the tank should keep it from losing a lot of fuel into the crankcase, but a small amount might still get in from what's left inside the pump each time that you shut it off.

I wouldn't run it until you get the seals replaced.
 
(quoted from post at 20:05:38 02/03/15) Does the throttle shut off cut the fuel supply thereby stopping this situation? I guess I need to find a diagram of the pump and go from there.

The throttle shutoff only shuts the fuel off to the injectors. As has been mentioned, you'd need to turn the valve shut on the bottom of the tank to stop fuel flow into and out of a leaky pump.

My best guess, with several of the others here, is that your drive shaft umbrella seals are the culprit. If they're old, likely your governor retaining ring and some other seals are as well. You can buy a seal kit, which will include the retainer ring and the umbrella seals for around $35.00 at your local pump shop or on eBay. There ought to be such a pump shop in the salt Lake City area somewhere.

If the seals are new, whoever did the work on the pump rolled the upper one on installation.

Several specific things you will need if you elect to work on this Roosa Master (now Stanadyne) pump yourself:

1. a clean workplace - cleanliness is an absolute must.
2. a good knowledge of how to time the pump to the engine. (I usually rotate the pump to the timing mark before I remove it.)
3. a good pair of external snap ring pliers for stretching the eyes of the governor retainer ring over the studs.
4. a Bristol bit tool (if the advance stud in your pump is the Bristol fitting type) A T45 torx bit with some relief ground to its points will work in the absence of the Bristol bit tool. (Do not attempt to remove this type stud with anything else. It will shatter.)
5. attention to detail as you disassemble the pump.

There are other things you'll want as well, but those are the high points.
 
Thanks for the detailed info Larry.

Awhile back I read a post on this site from a gent who had
sent his injector pump in for a rebuild and he was very
satisfied. I can't seem to find that post again.

Does anyone have any recommendation about where to get a
quality rebuild?
 
That thing was right at 100HP so to big for what I needed. My NH850 baler called for a tractor that was 55HP to 75HP so I figured why push my luck and use it when that might cause a major problem by having too many HP
 
(quoted from post at 09:27:17 02/04/15) Thanks for the detailed info Larry.

You're most welcome!

Unless it needs more than seals and a retainer ring, you can likely UPS it to someone like me, and get it back much cheaper than a pump shop will run it for.
 
My neighbor had a bad return line on his 861D. It is inside the valve cover.That will put diesel in your oil.
 
(quoted from post at 13:26:41 02/04/15) That thing was right at 100HP so to big for what I needed. My NH850 baler called for a tractor that was 55HP to 75HP so I figured why push my luck and use it when that might cause a major problem by having too many HP

If you have a slip clutch or shear pin on the baler to properly protect it then it should be fine with a 100 hp tractor. It'll just use more fuel than a 55hp to 75hp tractor would.
 
(quoted from post at 14:46:01 02/04/15) My neighbor had a bad return line on his 861D. It is inside the valve cover.That will put diesel in your oil.

As the original poster said, and as i pointed out to sunbeam when he said basically the same thing as you... The crankcase oil level was correct when he bought the tractor and he has only turned the engine by hand a few times since then, so how would that much oil get up into the return line without the engine running?
 
I did use it one season The baler has a shear pin set up. As for fuel it did very well and used very little fuel that summer. I now use an Oliver S88 to bale with and it does use a good bit more fuel then the XT190 did
 
It is best to have a manual before you get into that since to replace the seal you have to pull the pump off and then re-time it when you put it back on and bleed the system to get it to start
 
It is not uncommon for the stand pipe in the tank to brake off mine did in a 801 and a leak in the return under the valve cover kept adding to the oil level. Shut off the fuel at the tank if it keeps adding oil you shut off is bad or it's the return. Or pull the cover and look.
 
Back years ago when I did the pump on the A/C XT190 I had to have the pump rebuilt which cost me around $800. Took what seemed like forever to get it to start up but once it did it was easy to start
 
851D...Once I get the valve cover off, if it is a return line break (rather than just needs a tightening), OR if the standpipe is broken, any idea who would have those parts?
I haven't been able to find them.
Thanks!!
 
On an 851D...When I start the engine diesel sprays out around the breather vent on the valve cover. I'm thinking a leak in return line or broken standpipe, but...when I check the dipstick, it is straight diesel as one might expect, but it never goes above the "FULL" line on the stick. Odd?
Thanks!
 

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