Good evening.
I have an issue on my 51 engined ES2. The engine is fitted into a 59 Slimline Featherbed Frame and uses the Slimline oil tank. I bought the bike as a non runner.
I filled the oil tank to the required level and left it over night. The next morning the contents of the tank were all over the floor. The oil was coming out of the breather hole above the drive side main bearing!. A classic case of "wet sumping".
I decided to fit an inline tap, as per my 1948 M40 Manx. I know that this is not ideal, but needs must. (The Manx was already fitted!) This cured the wet sumping issue.
Once the bike was running I checked the oil return and noticed that the oil was not returning from the pump via the return swan neck at the top of the tank. Instead it appeared that there was a flow of bubbles coming out of the filter assembly! Now this indicates to me that the oil pipes are on backwards and the scavenge side is blowing air back into the tank and that no oil is going to the pump.
There are 2 unions on the crank case, one above the other. The Top one was (is) connected to the return pipe and the feed pipe from the filter, with inline tap, is connected to the bottom one. This was the way I acquired the bike, and is the same as the connections on the Manx. So I believe that the pipes are the correct way round.
Does anyone have any idea why I am not getting a return via the swan neck, and why there are bubbles / flow from the Filter assembly?
Many thanks.
Reverse order.
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Hi William,
With the oil pumps being a different design, the ES2 engine has the feed into the top entry and the return from the bottom with the rocker feed taken by a " T " union around half way up the pipe. This flow is restricted by the small hole in the top banjo securing bolt in the centre of the rocker box.