[NeilT595]

I think you need to look for air leaks in the Sump to pump pipe,they have been known to suck air past bad joints where they are soldered.Also once most of the oil has been cleared from the sump you no longer get a stream of oil back into the tank , only spurts of airy oil. The pump is designed to return twice as much oil as it delivers.
Sorry if you already know all this stuff.
John
Thanks John. I will have a look

[NeilT595]

What thickness of gasket is installed on the cover of the return pump. The original one is thin as Zygsretten paper. If the seal is only slightly thicker, the two ring gears cancel each other out. Pump power goes to zero. Many do not install a seal there.
My gaskets are definitely thicker than that so i will replace. Many thanks for that bit of info

[klaudius]

What thickness of gasket is installed on the cover of the return pump. The original one is thin as Zygsretten paper. If the seal is only slightly thicker, the two ring gears cancel each other out. Pump power goes to zero. Many do not install a seal there.

[singleminded]

I think you need to look for air leaks in the Sump to pump pipe,they have been known to suck air past bad joints where they are soldered.Also once most of the oil has been cleared from the sump you no longer get a stream of oil back into the tank , only spurts of airy oil. The pump is designed to return twice as much oil as it delivers.
Sorry if you already know all this stuff.
John

[NeilT595]

If you disconnect the return pipe from the sump after the bike has been running for a while does oil run out.

John

If you disconnect the return pipe from the sump after the bike has been running for a while does oil run out.

John
Hi John, as i tried to explain, the engine running, oil is pumped around the engine, top end etc and drops into the sump as it should. i have run the engine a number of times and still no oil return. If i then remove the sump to pump pipework, i have taken at one point about a pint of oil from the sump into a jug. so, with that amount of oil in the sump, why is it not being drawn up that pipe to the pump?. If i kick the bike over, not starting, with this pipe still removed, it looks like on one stroke of the engine, oil is pumped out, then on the next stroke the oil gets sucked back into the sump.

[NeilT595]

I'm slightly confused - the post heading says 1934 M9, but you say 1936 in the text. It would be useful to know the engine number also - it makes a difference!

P.
Sorry for any confusion, a miss pring on my part. It is a 1936

[phutton]

I'm slightly confused - the post heading says 1934 M9, but you say 1936 in the text. It would be useful to know the engine number also - it makes a difference!

P.

[singleminded]

If you disconnect the return pipe from the sump after the bike has been running for a while does oil run out.

John

[NeilT595]

I wondered if anyone can help me with an oil circulation problem I have.
Having recently restored a 1936 Model 9, I am experiencing the following.

When the bike is running, oil flows from the oil tank to the pump.
As the tell tale was in bits and not working, I have sealed the end, but before fitting it I made sure oil flowed to and from that side of the pump.
Oil flows up to the top end and tappets and drops down into the sump.

Now, here is the problem.

Oil will not flow up the sump return pipe to the pump, no matter if there is a drop of oil in the sump, or a good pint.

If I prime the pipe from the pump to the oil tank and start the bike, oil flows great into the tank until it has run out, yet still nothing in the sump to pump pipe.

So, has anyone had this problem before?

The system has a whole is working except for the sump to pump side of things.

Can anyone help?

Many thanks in advance

Neil