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jdemaris
01-11-2004 09:57:57
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Re: Re: Re: John Deere 350 Reverser Pump in reply to EdDavet, 01-11-2004 07:13:25
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I'm going by memory, but .030" clearance sounds excessive. Seems .008"-.010" would be more like it. I'm not sure which pump setup you have. Early machines had a two-piece pump housing with a removable pump cover (that holds the seal) that mounted with a gasket. With this setup wear on the main reverser front cover was not an issue. Later machines had a removable one-piece pump housing with a square-sided o-ring and was held on by four bolts. With this setup, the pump gears turned directly on the machined surface of the front cover. So, with this later setup, the pumphousing is the highpressure sealing surface for one side, and the main front cover is the other. We had reversers that got trashed and the main front cover was scored up. Usually, it could be remachined and smoothed a bit. If the one-piece pump housing was scored, we just replaced it (easy to do, I guess, when you're not the one paying for the parts). Seems it's kind of hard to machine the inside of the housing, and machining the outside - to lessen pump gear clearance, would require remachining the o-ring groove that same amount. In real world situations rather than theoretical, a highly worn housing should be plainly evident, by eye. If it doesn't look worn or scored, and worked okay previously, I'd assume it will continue to be okay. When rebuilding reversers, we always replaced the pump gear sets but only replaced the pump housings when scored. It would be interesting to take a new housing and pump gears and measure it for comparison. That's luxury a mechanic at a dealership has, that perhaps you don't in your shop. Keep in mind also that the input shaft - with .002"-.004" endplay is going to have side-to-side movement until it's bolted to the engine and its stub is riding in the pilot bearing (or bushing in older machines). Another somewhat unrelated issue to make sure the oil orifice is in place (in the output shaft), tight, and not plugged. It very often gets damaged in trashed reversers, and I've seen a few that got new shaft installed where the assembler forgot to put it in. Won't work very well without it.
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