new person with sad problem

The oil must be getting by those gears somehow!!

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A friend a compenent engineer has a 750 Commando, his first old Brit and Norton and it wet sumped badly. Years later and after fitting an anti-drain valve the motor nipped up both big-ends goosed and a rod bent. And it rode home like that, amazing. Out of interest I ask for the old pump, I've got to admit I took it to bits and held that pump in my hands for ages knowing something was missing but what ? it was the short spindle. It's no wonder it wet sumped but hell it even pumped oil.

The good news is he's still hooked like the rest of us sad b*****ds.

Cash

cash said:

The oil must be getting by those gears somehow!!

Click to expand...

Out of interest I ask for the old pump, I've got to admit I took it to bits and held that pump in my hands for ages knowing something was missing but what ? it was the short spindle. It's no wonder it wet sumped but hell it even pumped oil.

The good news is he's still hooked like the rest of us sad b*****ds.

Cash

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Are you saying the short spindle was not there, and the gears were just resting in the housing? :shock: Something to think about...but i know i took the rebuilt pump apart and i am pretty sure all the pieces were there (that was 3 years ago, though...)

L.A.B. said:

tpeever said:

The oil must be getting by those gears somehow!!

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But we have to take into account that oil would not necessarily have to pass through the pump in order to drain to the sump.

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This is an interesting idea. how would oil get into the sump from the tank without passing through the pump? I have to admit i dont have an oil diagram in front of me to study.

mjfriesen said:

L.A.B. said:

tpeever said:

The oil must be getting by those gears somehow!!

Click to expand...

But we have to take into account that oil would not necessarily have to pass through the pump in order to drain to the sump.

Click to expand...

This is an interesting idea. how would oil get into the sump from the tank without passing through the pump? I have to admit i dont have an oil diagram in front of me to study.

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Do you suspect a leak in the feed to the oil pump?

Here's some related reading Mike:

wet-sumping-redux-t5704.html?hilit=oil%20pump
oil-return-problem-t6418.html?hilit=oil%20pump
anti-sump-failure-t5677.html?hilit=oil%20pump
where-has-all-oil-gone-t6337.html?hilit=oil%20pump

It makes sense that if there was a leak between the valve and the pump that it could contribute to both the wet sumping and the starvation issue.

carlo said:

TO NEW SAD GUY-I have a complete rusty crank under my work bench-will need sprucing up(10 under/bolt kit ) 72 I believe, in pieces --free if you want it

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Are the 750 and early 850 cranks the same? I know the MkIII isn't or he'd use the MkIII he has.

mjfriesen said:

Are you saying the short spindle was not there, and the gears were just resting in the housing?

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Exactly that.

Cash

mjfriesen said:

L.A.B. said:

tpeever said:

The oil must be getting by those gears somehow!!

Click to expand...

But we have to take into account that oil would not necessarily have to pass through the pump in order to drain to the sump.

Click to expand...

This is an interesting idea. how would oil get into the sump from the tank without passing through the pump? I have to admit i dont have an oil diagram in front of me to study.

Click to expand...

you should not need an oil diagram. it is a simple system just follow the line and drilled passages. look for missing blanking plugs, passages drilled to the point of break through and another look at that oil pump.it could bypass between the pressure and scavenge sides where the shaft's pass through the body. if the mod with a check ball was done on the timing cover than look at every thing from the inlet line on the case half to the discharge side of the oil pump including the timing cover pressure relief return port.

bill said:

you should not need an oil diagram. it is a simple system just follow the line and drilled passages. look for missing blanking plugs, passages drilled to the point of break through and another look at that oil pump.it could bypass between the pressure and scavenge sides where the shaft's pass through the body. if the mod with a check ball was done on the timing cover than look at every thing from the inlet line on the case half to the discharge side of the oil pump including the timing cover pressure relief return port.

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I think i understand now - it's not that oil should get to the sump without passing through the pump, but that something may be wrong! The cases are nice and clean, and in a good position to be looked at. I will report back! :wink: