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I went through changing the shaft seals on my recently purchased 310D backhoe. Most of what I learned I got from the various ytmag boards, including the Deere and Case boards especially. Do a search on "shaft seals", "Stanadyne", "Roosamaster", and "diesel in crankcase". I didn't tackle the actual job until I got the service manual, but it didn't add much more other than explaining the difference between the "retained shaft" and "non-retained shaft" pumps. None of the material makes completely clear the exact procedure for getting the pump back on without "flipping" the seals, so let me try to add my experience to the tribal lore. I'll assume that your 300B has a Stanadyne or Roosamaster non-retained shaft pump. You remove
the pump by removing the fuel injection lines and the three retaining nuts. When you pull the pump off, the drive shaft stays with the engine. It is normal for the shaft to "flop around" in the timing case once the pump is removed. If you are suffering from diesel in the crankcase, the usual cause is the rearward umbrella seal. It will have "flipped" or
rolled over on installation, and will appear
distorted. The forward seal should be fine, since it is supposed to face the opposite way -- wide end towards the timing case -- this is the easy direction for installation. The rearward seal installs with the wide end facing towards the back of the engine. This causes it to "fight" the natural movement of installing the pump as you push the pump forward.
There is only a tiny bit of feedback that this is happening as you install the pump -- so it is easy to do it wrong every time. Here's a method that worked for me. The dealer didn't have the seal compression tool. I went down to the local auto parts chain place and found that a fuel line hose disconnect tool for Ford products has a 7/8 inch setting that is almost an exact duplicate of the Deere tool, and costs the princely sum of $4.75. Next, I loosened the clamps securing the injector lines and pushed them out of the way so that I would not be fighting them as I attempted to install the pump. Next, I removed the undamaged front seal, reversed it, and installed it as a "practice" rear seal. Oil it up with a light coat of engine oil. (I figured if I could get the pump on and off a few times, without flipping the seal, with a used and hardened seal, I could reasonably expect to succeed with a set of new seals.) Compress the seal onto the shaft with your tool, using your left hand. With your right hand, ease the injector pump onto the drive shaft. Push the injector pump on until it pushes the tool most of the way off the seal. At this point the tool is useless -- so remove it and drop on the floor. The "moment of truth" comes just as the last of the rearward seal disappears inside the injector pump. As you try to push the pump further on, you will feel a slight resistance -- this is where the seal wants to flip over. At this point -- STOP. Don't try to just shove the pump the rest of the way in. Instead, what you must do is to wiggle the pump very slightly up and down and left and right with your two hands, as you try to get the pump and seal to become perfectly coaxial with each other -- and the pump to move in further without just forcing the seal to roll over. The slight resistance to further inward motion that you feel will "pop loose" once you get everything aligned. It's very subtle and you won't be able to feel it if you are also fighting fuel injector lines that are interfering with the pump. Don't confuse this with the significantly higher force resulting from forcibly rolling the seal over. If the brass sleeve inside the injector pump is not grooved, the pump should slide the rest of the way on with no problem and no resistance, and no further threats of "seal flipping". The forward seal takes care of itself, and you don't need the tool or any special procedure for it. Obviously, try to hold reasonable alignment with your hands and don't let the pump "cock over" on the shaft as you push it on. Now remove the pump and see how you did. The pump should slide right off (without the resistance of a flipped seal). The seal should look just as it did when you installed it. When you can do this several times in a row you are ready to try with a set of new seals from the dealer, with a reasonable expectation of success. I was quite amazed when the backhoe started right up and the deplorable condition of "making oil" was found to be fixed. If I can do it, you can too. Good luck!
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