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jdemaris
03-13-2005 07:40:42
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Re: JD310A Injector Problem? in reply to Jason E, 03-13-2005 00:21:04
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The part that fails in the JDB or DB pump is part of a three piece assembly that holds the weights in the centrifugal governor. There is the steel weight holder, the steel drive ring, and the plastic dampener/drive-ring that holds the two steel pieces together. This dampener is plastic or rubber of some sort - it gets brittle and eventually shatters, falls parts, and runs through the pump. The material it's made from has been updated several times over the years - so I assume the new ones are better than the old. Most diesel shops that I know of just replace the rubber ring and don't update the assembly. If you wish to update the assembly, it can be replaced with the parts from a DB2 pump. The DB2 assembly does not use a soft drive ring, but still provides dampening and I've never seen one fail. It will cost around and extra $50. In regard to the pump driveshaft - it will stay attached to the engine when you pull the injection pump off. It is fastened to a gear in the front of the engine and held on to the gear by a nut. It is also spring loaded - a light spring keeps tension on the shaft towards the direction of the pump. When you pull the injection pump off, the shaft cannot go anywhere and will not and can not fall out of time. When the injection pump is off, you will have to disassemble it down to a few major sub-assemblies - i.e. the head and rotor is removed as a unit from the soft-metal pump housing. There are various small parts that should get new o-rings which come in the new seal kit. You really ought to have a manual to guide you along the way. Many tractor companies included detailed pump repair information in their manuals, but Deere did not. Deere put the information in a separate manual SM-2045. My Allis Chalmers manual for my HD4 does provide all the info, so do various manuals I have for diesel Ford and Case tractors. They all use the same basic Roosamaster DB pump - so maybe you can find a book locally? In brief - although this might not make sense to you without photos - you pull the top cover off the pump held on by three small bolts. Remove the long bolt that goes through the trottle/govenor spring with a 7/16" wrench. You knock out a retaining clip and remove the throttle shaft assembly - it's in two pieces. You take the bottom cap out the the pump (large screwdriver slot), then go in and take out the cam-ring stud bolt. NOTE - in Deere applications this requires a special fluted wrench. In most Fords and others it's an standard Allen/hex head, but not Deere - needs wrench # 15499. this bolt is ball shaped at the end, and activates the timing advance. So, you will notice that it has two components pushing against it from two sides - those components must be removed before the bolt is removed. Once the ball-headed bolt is out, there are three bolts holding the soft-metal housing to the head & rotor assembly. The bottom bolt has a twelve-point head and takes a standard 7/16" wrench, the others take a 1/2" wrench. Once the three are out, the housing will pull off - all that holds it is the tension of a large o-ring. Might need a soft hammer to get it started. When you separate the housing from the head & rotor, you'd best have the head & rotor pointing down, and pull the housing off in an upward direction. Otherwise, some small part (weights, washers, etc.) will fall on the floor. Once the housing is off, you'll be looking at the governor assembly. The parts you will probably need are #1 the seal kit approx. $28, #2 the bronze drive bushing approx. $11, and #3 a new housing pressure regulator valve approx. $10 - that's the fitting that gets plugged on top of the pump. It has a small check ball and spring in it and sometimes gets ruined in attempts to clean it. So, if you bust it - get a new one. The seal kit used to be available right from Deere - perhaps not anymore? I don't know. I bought a couple of kits a few weeks ago for $28 apiece, most diesel shops sell them to you. The kit comes with all the soft seals, umbrella driveshaft seals, o-rings, plastic governor weight retainer ring, steel injection line washers, and a new updated fuel regulator plug. In regard to the bronze bushing - I just bought a couple at $11 each. This is the bushing at the drive end of the pump where the driveshaft and umbrella shaft seals ride. It gets grooves worn into it over time. Once it gets the wear grooves, it very difficult to get it to slide over new seals without flipping/destroying them. I heat the housing around the bushing a bit, drive it out, then use epoxy to glue the new one in. So, when your pump is off, eyeball the bushing. If it has grooves, now's the time to replace it. There are other wear items in the pump, but it's kind of hard to sit here and explain it all. When I was a Deere field mechanic, usually I'd be working on a machine down in the woods or field. Time was of the essence, the owner needing the machine, so - often I'd pull the pump off, take it apart on the tailgate of my truck, put the new parts in, and have it running again in a couple of hours. That's what I call a pump repair, not a complete rebuild. It usually worked out fine. When time is not of the essence, and you've got the pump on the bench - I prefer to take it all apart and check everything. Many of the high-pressure pump parts get checked visually - for wear marks - and by feel. Tolerances are so close that a micrometer is useless. I know of many of these pumps with well over 50,000 engine hours with no major parts replacement - so the parts are pretty rugged as long as they don't get water or bad fuel in them. I've heard that highway low-sulfur fuel cuts down their life and farm fuel/heating oil has better lubrication. In fact, Roosamaster/Stanadyne sells "extra-durable" steel parts for these pumps, listed as "Artic." Those parts were originally intended for very cold climates where the fuel is cut very thin with kerosene and wear was more of a problem. They are sometimes used now in applications where highway fuel is used instead of heating oil/farm fuel. They are costly, though. In pumps with high hours, usually the following parts have some wear and might warrant replacement during a true rebuild. The fuel metering valve - this constantly moves back and forth to control RPM. The low-pressure fuel pump vanes and liner in the back of the injection pump. The injection pump has its own low pressure fuel pump built into the back of it. This low pressure operates the fuel advance. The spring loaded vanes get worn over time - and to a lesser degree - so does the liner they turn in. There are other parts of course, but these are the most common wear items. It all sounds technical and complicated - but what doesn't when you haven't done it before? If I have a pump on the bench, it takes less than an hour to go all though it. In my situation, I get to install the pump I fix back on the machine, and subsequently test and/or adust it once running. A guy in a pump shop does not have that capability, so he (or she?) has to install it on a test bench instead to set it up and/or check it. That sometimes takes more time than the rebuild, and some of those test benches cost $50,000! Thus, pump work can be expensive.
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