Diesel fuel Injector pump leaking into crankcase?

[gabmux]

Hello. I have a 254 Chinese tractor with 3 cyl. LaiDong engine.
The crank case keeps getting filled with diesel fuel somehow.
I'm guessing the fuel is getting through from the injector pump maybe?
Are there perhaps some kind of seals in the pump that I could change?
Or a leaking gasket maybe? If I replace the pump would that stop the leak?
Thanks for any information you can suggest

 

[piper184]

Depending on what injector pump you have, it might be possible for a leak to get into the crankcase through the front timing gear housing.
Another possibility is an injector that is leaking and letting fuel wash down past the piston rings.
I can't think of any other places where diesel would get in, unless the "lift pump" is powered by the engine cam shaft and not part of the injector pump. Think old style car engine fuel pumps mounted to the block with an arm that rides on the cam. On my Jinma 284 the lift pump is mounted on the injection pump, not the block. When it failed internally it dumped diesel into the crankcase of the injector pump, which over flowed through the breather. Not the same thing as getting fuel into the engine block.
Post a picture of your fuel system so we can see exactly what is involved.

 

[Bob Rooks]

The fuel injection pump on some engines are lubricated with oil from the engines pressure system. If that is your case you will have an oil line connected to the engine block, and another connected to the sump.

 

[gabmux]

Thanks much to both of you for kind replies! I will try to attach photos here if I can.

 

[gabmux]

 

[gabmux]

I did have a bad injector once quite a few years ago which I had to replace. But that bad injector caused noticeable misfiring.
But now this engine doesn't seem to misfire at all. The problem is that eventually the diesel fuel overfills the crankcase and the engine starts pumping out diesel fuel mixed with the engine oil up and out through the exhaust stack pipe.

 

[gabmux]

I can drain the crankcase and change the oil and filter and the engine will run great for maybe a week or so depending on how much I use it. But if I check the oil before each use, I can see the gradual rise in crankcase level by the marks on the dipstick.
But I really don't know if the leakage occurs only when the engine is running (or not running) or if the leak is present at all times.

 

[thepumpguysc]

The lift/supply pump is bolted to the side of the inj pump.. it’s the pump with the hand primer on it.. it has a seal or oring on the back side that’s facing the inside of the pump..
You can remove it, block off the outlet side and put air on the inlet side and dunk it in water or spray it down w soapy water and look for bubbles..

 

[gabmux]

The lift/supply pump is bolted to the side of the inj pump.. it’s the pump with the hand primer on it.. it has a seal or oring on the back side that’s facing the inside of the pump..
You can remove it, block off the outlet side and put air on the inlet side and dunk it in water or spray it down w soapy water and look for bubbles..

Okay it looks like only (3) 10mm nuts holding the lift pump in place. I will remove those (3) nuts and attempt to separate the lift pump from the injector pump. I will remove both inlet and outlet fuel lines from lift pump. Then block fuel outlet side of lift pump and apply air pressure to fuel inlet side of lift pump. I can then dunk pump in water or spray it with soapy water and watch for bubbles.


I will be looking for the bubbles on the lift pump where the lift pump attaches to the injector pump?

Is that correct?

 

[thepumpguysc]

On the “back-side” of the lift pump, there will be either a roller or a plunger that rides on the pumps cam lobe..
Behind that will be a seal or oring.. u can just dunk/spray that area..