Twin oil filter.

bruv · Post by **bruv** » Sat Oct 15, 2011 6:43 pm

Can anybody please help.
I recently purchased a 1959 G12CSR crankcase complete. Its number is 59 G12CSR 08709. I suspct that the engine has the wrong oil filter assembly fitted in it. When I removed the filter from the crankcase I discovered a one-piece unit that incorporated the oil "non-return valve". The filter itself is a metal mesh design with two different mesh sizes, one inside the other. The engine has no oil pressure relief valve fitted, either in the base of the filter tunnel, or in the timing side crankcase. I expected to see the earlier fabric felt filter used in this engine, with the "non-return valve" as a separate unit. My questions are :-
(1) Should this engine have this type of filter fitted in it?
(2) Can I safely use the one piece filter in the engine, as I found it?
(3) Should I throw it away and use the earlier felt fabric type filter as supplied by the club.
Any help or advice would be much appreciated. Many thanks, Bruv.

Don Madden · Post by **Don Madden** » Sat Oct 15, 2011 7:31 pm

The factory seems to have stumbled around a lot with oil delivery in twin engines. They had a couple of different designs of oil pressure relief valves through 1955, then for 1956 deleted it completelym resulting in excessive oil leakage. The engines used the fabric filter until 1960. That year, they admitted the error of non-regulation & placed the regulator at the T/S end of the filter tunnel. As this interfered with the long fabric filter, they switched to the shorter wire mesh, attached to the non-return valve as you have. A couple of years later they added a layer of felt around the wire mesh but this restricted oil flow By 1964, they realized the wire mesh filter to be inadaquate & reverted to the original felt by relocating the regulator in the alloy pump mounting plate. Best remedy is to replace the pump mounting plate with the later, if you can find one, & put in the original felt filter. Other mods are possible but more difficult. An external BSA/Norton type filter can easily be put in the return line to the tank but does not solve the lack of regulation problem. Cheers, Don.

wilko · Post by **wilko** » Sun Oct 16, 2011 3:48 am

Unfortunately i don't think you'll find one of those late model pump plates, as they are a desirable mod with the wider gear oilpumps.

bruv · Post by **bruv** » Sun Oct 16, 2011 12:01 pm

Dear Don Madden and Wilco,
Many thanks for your advice. The way forward is now much clearer !! I will revert to using the original type of filter and hope that I can keep the engine oil-tight. In the long term, I will keep a look out for the later model pump plate. Thanks once again, kind regards, Bruv.

wilko · Post by **wilko** » Mon Oct 17, 2011 12:53 am

Just don't over rev it when it's cold they can reach 120 psi!If there is a casting blank in your cases it would be easy to make the plunger but you would need a sample.