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Gravely 2-wheeler
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935 Posts
Discussion Starter #1
I have a '50 L with a low volume oil system. It recently stopped pumping oil. The crankcase is more than full of SAE40. Before I start pulling oil lines to check for blockages and pump operation I noticed a fair amount of play on the timing pinion shaft where it exits the oil pump cap. It is leaking some oil there and would likely allow air to enter. Would this account for the loss of oil pressure or do I have two separate problems, a worn bearing with a bad seal and a separate lube system problem? How involved is replacing the timing pinion bearing and bearing cap double seal? If they are unrelated the lube system problem is the more urgent issue and suggestions for diagnosis are welcome.
 

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Premium Member
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4,183 Posts
By crankcase, you mean the transmission, right? The oil pickup is down at the bottom of the tranny, under the final drive gear.

If you're leaking air past the shaft into the oil pump, it's possible that the pump has lost prime. Especially on the low volume pump, it doesn't take much to fill it with air, and it does take a little while for it to get the air out of there.

What I've done to re-prime a pump is to disconnect the oil line at the filter end, and rig up a piece of plastic hose or something with a funnel, so I can pour oil down that line backwards. You can just let it sit a while, or turn the engine backwards until you get sick of doing so, to run the pump backwards and fill the pump and lines. Then reconnect and start it up and see what you get.

That's a pretty simple procedure, that doesn't involve disassembling a lot of stuff.

If that works, IOW you get oil flowing, but then after you shut it down and let it sit a while, it stops, it's a pretty sure bet your pump is losing prime. That means you do need to disassemble and repair, as you suggest above.
 

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Gravely 2-wheeler
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935 Posts
Discussion Starter #3
So far I have let it sit for half a day with the nose up and the handlebars on the ground so that the oil pump is the lowest point on the tractor. (That is how I noticed the oil leak.) That usually works to prime the pump. I turned it over with a large slow electric drill with the spark plug out. Still no oil flow. Today I'll pull a few oil lines and see what I find. I think I can run it with the drill with the oil pump as the lowest point if I take it outside when it stops raining. I also have a trigger pump oil can that I can hook up with some vinyl tubing to an oil line to prime the pump.
 

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Gravely 2-wheeler
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935 Posts
Discussion Starter #4
I think I found the problem. The oil line from the pump to the filter was clogged. I cleaned it and reassembled it but before I could prime the pump we lost power in high winds so I went on to another project. The pump and filter output line seem OK. I'll get back to this issue probably on Monday. I have an oil mess to clean up in the garage from drips that missed my pan and the tractor will need a good bath with engine degreaser and hot water when I'm finished.
 
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