Dead Hydraulics

[VGyanmar-HT]

Ok so I have a yanmar 336D with a bucket and box blade. I was pushing up rock to pile it higher the other day when while trying to back off the pile my box blade got snagged on a manhole cover on the street. The tractor was sitting at a fairly steep angle while I got off and got a bar to lift up a bit on the drag box to release it from the manhole cover. When I backed off the pile all my hydraulics were dead. I thought maybe all the oil flowing to the back end of tractor caused the pump to fail. So i ordered a pump, put it on and still nothing. My pump on this tractor is splined so it doesn't have a key to break. My question is now what to do next to diagnose what caused this? Was it the steep angle tractor was on or getting box blade unstuck by pulling it up slightly? Oil and filters were clean but I replaced anyway when put new pump on. I have service manuals but still may be over my head finding the issue. Located in central illinois if anyone could recommend a place that is good with these problems. Thanks to anyone with any ideas to help.

 

[Aaron-HT]

Does the tractor still move correctly... the powershift is still working?

I can't really think of anything in that scenario that would cause both the loader and three point hitch to stop working and the pump still be ok (aka not cracked or shaft twisted off).

Is the pump moving oil? If you remove the outlet line from the pump does it make a mess?

 

[winston-HT]

Maybe an air lock on the pump suction side since installing new pump?

 

[VGyanmar-HT]

So if airlock was the case how would I fix? I took the output line from pump to divider block loose and cranked motor yesterday.I get nothing from new pump.

 

[VGyanmar-HT]

Tractor moves forward/reverse fine. no power steering obviously.

 

[Aaron-HT]

I would probably just pour some oil straight into the pump to help get it primed. If you run it too long without oil you can burn up the pump.

 

[VGyanmar-HT]

Tractor moves forward/reverse fine. no power steering obviously.

 

[winston-HT]

<QUOTE author="Aaron"><s>

</s>I would probably just pour some oil straight into the pump to help get it primed. If you run it too long without oil you can burn up the pump.<e>

/e></QUOTE>

In addition to that, if you haven't already, might fill the suction filter with oil before screwing on.

 

[Aaron-HT]

The filter on that model lays horizontally which makes prefilling tough but I think it is pretty close to (or below) the oil level so it should fill on its own. It would be easy to test- just unscrew the filter a little and see if oil runs out.

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[VGyanmar-HT]

yes i did fill filter best i could but will check. Going to take steel input line off asap and fill pump with oil. worth a try. thanks.

 

[VGyanmar-HT]

Well took input line off pump. Pump appeared to be pretty full of oil but I took funnel and topped it off with oil till running out. Reassembled line to pump but still no hydraulics. I guess I may take whole thing apart again and inspect it further.

Trying think of way to test pump while off tractor. Perhaps buy the fittings to convert pump from steel lines to regular hoses. Then hook up hoses to pump, stick input hose in bucket of oil and spin pump with a drill to see if it pumps anything. Can't keep buying pumps if something else causing them to go bad. Anyone got a better idea?

 

[winston-HT]

Once off I would think you might turn the pump by hand and see what is happening.

 

[winston-HT]

Once off I would think you might turn the pump by hand and see what is happening. Wondering if there is a drive problem with coupling or bad drive gear?

 

[VGyanmar-HT]

Found more time to work on yanmar. Removed new pump and put on my work bench. Filled with oil and turned spline by hand counterclockwise. Oil came out output line of pump. Reinstalled pump with new coupler onto tractor but still does not work. Someone suggested air in lines so I rigged an air hose to pressurize and push oil thru to see if blockage. Took loose pump input line to pump, applied air and oil came right through. Then removed top bolt on divider block AFTER the pump, applied air and also got oil flow so no apparent blockage. Took loose input line again and aimed a flashlight down input hole in pump while I had someone crank over motor but not start it. Hard to see but I do not see gears turning in pump while cranking motor. Pump new, coupler new. I did crank over motor when had pump off the first time to make sure the slot the coupler fits into moved positions when motor turned. Guess possible slipping inside motor but I don’t know. What does etched arrow facing down on new pump mean? Assume it means down and not a direction pump supposed to turn. I put new pump on exactly as old pump. Frustrated.

 

[Aaron-HT]

<QUOTE><s>

</e></QUOTE>

I think this is the key sentence. If the pump gears are not turning then none of that other matters. I can't really think of what would cause the pump to not get driven but it sounds like you need to find why the pump stopped turning.


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[VGyanmar-HT]

yes agree. looks like a big job take front cover of motor off. Looking through that square access plate on side of motor above pump, appears to be turning but really hard to see using a mirror. Thanks for your thoughts.

 

[Aaron-HT]

<QUOTE><s>

</e></QUOTE>

Yes... I would make 100% sure the pump is not moving before going that path. I might even take the pump back plate off and turn the engine over by hand to verify. I just can't think of any way that drive gear could not turn and still have a running engine unless some teeth sheared off or something but that would be very unlikely.

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[VGyanmar-HT]

Well finally got problem resolved. Turns out I apparently did not get coupler and slot it goes into aligned well enough. Pump bolted up flush with housing but was not engaged in slot inside motor. I could take off the side access cover above pump and with a mirror observe coupler didn't turn when had someone crank motor. Took pump off a third time and instead of having coupler on pump when I reinstalled it, I put coupler inside motor into the slot and then installed pump into coupler. That way I know it was lined up. I got coupler to stay in place by rotating motor until slot was horizontal at 3 o'clock and 9 o'clock. Then took some grease and dabbed it onto end coupler to help hold it in place in the slot. Next I carefully slipped spline on pump into coupler already installed in motor housing. Whether its correct way it worked for me. Still amazed it bolted up with coupler being in slot but guess I learned something. Hope this helps someone else if they run into this. Thanks for everyones help.

 

[Aaron-HT]

I'm glad that you got it going again but I'm afraid it is probably not going to last very long as you have described it. It sounds to me like you might not have installed the little snap ring into the coupler. The snap ring prevents the coupler from sliding too far onto the pump shaft... which is what sounds like is happening.

 

[VGyanmar-HT]

Hmm. Don't remember seeing a snap ring for coupler or place to go into. I checked pump shaft for a slot for something like that but didnt see anything. At any rate, I'm pretty good at taking this apart so no biggie. May have to order a snap ring. Thx.

 

[Aaron-HT]

The snap ring will go inside the coupler just to prevent it from sliding on too far. There is not a groove on the pump shaft.


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[VGyanmar-HT]

ok. thanks. Not aware of that. Father in law replaced pump a few years ago so not in old one. I can fix that easy enough.

 

[VGyanmar-HT]

Any chance know what size snap ring goes in that coupler? Guess that explains why it happened in first place. Tractor was elevated at such an angle coupler fell back out of slot. Also may mean old pump is still ok for spare.