Oil weeping from the oil pump pistons

[dennis.t]

On my VH500 the oil pump is weeping oil from the pistons and that is running down into the bottom of the mag chain cover. Is this normal and does the oil that reaches the bottom of the cover drain back into the sump somehow?
The pump is returning oil to the oil tank when the engine is cranked by hand ( I have not started the engine yet.) and oil is getting to the rockers so I am hoping the pump is working OK.
Dennis

[JohnnyBeckett]

hi i think the pump is worn the pump does not normally leak past the pistons

[Roger Gwynn]

but oil does get into the chamber where the pump is and some is almost bound to leak past the pistons under pressure. There is a drain hole at the bottom of the case. It is unusual for the pump to be badly worn as it pumps oil so is usually well lubricated.

[dennis.t]

Thanks both. The pump does seem to deliver a good quantity of oil so I will keep it under review.
Roger, when you say: "There is a drain hole at the bottom of the case" do you mean the oil drains back into the engine or that the oil has to be drained off manually periodically?
Dennis

[volker.halbach]

The oil drains back into the crankcase. When the oil is hot and the viscosity lower, more oil may leak past the pistons.

[dennis.t]

Volker, many thanks. I am going to run the engine with the magneto chain case cover removed to see how much oil is seeping past the pump pistons. I will look for a pump in better condition in the meantime.
Dennis

[paul.jameson]

If your oil pump will return oil to the tank and get it up to the rockers by turning the engine over by hand there is little to worry about. You will always get a little oil coming out round the pistons but it is negligible in quantity. Remember that oil is like blood - a small leak looks a lot worse than it really is. The oil pump in my 1937 Red Hunter has never been rebored and works as well now (40,000 miles later) as it did when I first bought the bike in 1975. It is the best lubricated part of the engine.

I see from previous posts that your bike is a 1954 model. This one only has the single ball valve on each side of the pump so can be prone to failure. It would be worth fitting the secondary ball valves as per the September 1956 Service Bulletin.

[dennis.t]

Paul, many thanks for this information. I was not aware of this modification.
Dennis

[dennis.t]

Well the upgrade to the pump seals, described in Service Bulletin 125.1, did not go as easily as expected. Firstly, the timing gear cover had the remains of what I assume is a previous plug (2150-57) that had been drilled to remove the end leaving just a sleeve so that had to be drilled out for the new plug, spring and ball to fit. Then, having ordered a 9/32" drill bit BEFORE the plug, springs and ball bearings arrived from Drags, I found the plug was a larger diameter, actually 7.8mm not 7.114mm. I only have an 8mm drill bit so I used that and some Loctite to take up the slack (the pump holds the cap in place). I have yet to put the oil pump back on. What fun.
Dennis