Oil Pump Washer?

[Deano400]

Yesterday when I went to use my ultrasonic bath I found a washer in the bottom. Having given it some thought I think it belongs to the oil pump. The thing is I don't remember seeing it when I cleaned the pump. So pump is back off the bike and I think I can see where it should go, position A in the picture, but could be position B. Or I suppose it could be neither. I would appreciate it if someone could confirm either way. TIA.

[Bryanj]

Have you recently washed out the filter housing? Without sizes looks a bit like the washer between filter and spring.

[Nurse Julie]

Can you measure it John ?. I can then see if it's the same size as any that are in the CB400/4 oil pump kits I sell.

[Nurse Julie]

The oil pump shim is 14.80mm OD and 11.10 mm ID. Thickness 1 mm.

[Deano400]

The washer (shim) is 14.95mm OD, 11.30mm ID and 0.98mm thick. I'm thinking it is the oil pump shim, the measurements are pretty close to your replacement Julie. Also I'm sure the last thing that was in the bath was the oil pump parts.

[Deano400]

Have you recently washed out the filter housing? Without sizes looks a bit like the washer between filter and spring.

No Bryan, most recent in the bath was the oil pump. I change the solution each time I put something new in so I am thinking it must be from the oil pump.

[Bryanj]

You are probably right, never had the reason to stir a 400 pump and nothing in the 500 one so just throwing ideas out there

[thegreatpan]

Is an oil pump rebuild a must do?

[Deano400]

Is an oil pump rebuild a must do?

There are two reasons I tackled the oil pump.
1. One of the gearbox bearings was damaged shedding metal and some of the mains and big ends had clear signs that metal had been round the engine. So I wanted to check the state of the pump, some marks but still usable.
2. The age of the O rings, assuming no one had previously replaced them they would be 40 years old and getting tired.

[Laverda Dave]

It's the oil pump washer and it sits in the housing under the oil pump gears. I didn't see mine either when I took it apart as the oil in the pump body makes it stick in the housing only to fall out when you put it the parts washer!

[Deano400]

Thanks Laverda120. Is that position A in my picture above?

[Laverda Dave]

Yep, position A. Put the spindle in first and place the washer over the spindle. Fit the dowl and then add the pump rotors and outer pump body. Use plenty of oil.

[Deano400]

Thanks again Laverda120. First job tomorrow.