A10 Road Rocket leaking

Hi,

my next project is a 1957 BSA Road Rocket. The bike is in a really good condition and rides nice and tight with good compression.

The problem with her is - surprise, surprise - an oil leak. If i fill up the oil tank to the normal level (about 2 " from full) she starts to leak and does so for a couple of days, until it gets down to half full, at which point it stops. This happens without starting the engine.

The oil appears to be coming out in the region behind and below the cylinder barrel, where the crankcases come together at the back of the engine.

Is it normal, that oil would be fed to that area of the engine without the motor running? If so why does it stop leaking at half full and not empty the oil tank completely?

To stop the engine filling with oil when sitting in the garage the A10 has a non return valve in the timing side crankcase, to get to it is a crankcase apart job, the grub screw is under the main bearing bush and is staked. It can be a pain to get out, behind the grub screw is a spring and ball, replace both. The seat for the ball will be worn so you will need to drop the new ball in and give it a sharp rap with a hammer and drift to get the softer aluminium to conform to the shape of the ball.

Hi Kommando,

I have talked to SRM about my problem and ordered a new oil pump (the recess for the scavenge gear was heavily scored) and a new pressure release valve. In all probability the oil is coming ou not the floor through magneto which also fills up with oil in extreme cases of wet sumping, it drains out on the engine side of the magneto (apparently there are drain holes) and runs down the back of the crankcase between the rear engine mounts.

That will work until the SRM pump gets some freeplay, they may wear less than a BSA pump but everything wears and the pump once worn will leak oil through to the non return valve which you have not fixed. Fitting an oil filter in the return will protect the oil pump from crud getting to the oil tank and then the feed gears in the pump. And wear in scavenge gear will not cause a wet sump, only wear on the driveside does that as that is the route for the oil from the tank.

I have placed 2 orders with SRM and they messed them both up and now to see the rubbish advice they gave you confirms they reputation is grossly inflated.

well not only was the scavenge side deeply scored, but also the end plate for the oil pump was not fully tightened (one turn opened) ...once tightened, the pump would not move at all. In an attempt to keep the screws in this semi-loose position the PO has dot punched to "lock" the screws" (Why the hell people do such things is beyond me).

I agree, that if the non return valve does indeed play a role in this, then SRM have given crappy advice to not even mention this. As mechanics, SRM are obviously no better (or perhaps worse) than you're average classic mechanic, but they do make the parts which are otherwise not available, so i am happy they're there!!