Oil Pressure Relief Valve Replacement 1967 B44R

[B44R Victor]

Hi,

I'm wanting to replace the spring and ball oil pressure relief valve on my 1967 BSA Victor Roadster and have managed to obtain a replacement spring, ball and plug if I need it but when I examined the plug more closely, which is in the front lower engine casing, I found the plug is so tight up against the casing, exhaust and frame that no box spanner or open ended spanner I have in my tool box can loosen it.

This is a routine maintenance item, so there has to be a simple way to do this.

Please, does anyone know where I can get hold of a suitable short thin box spanner to fit a 13/16th face to face plug? Or how do I do this?

Best regards

 

[Spaceman]

I can't quite get to my B44VS but I can see what the problem is. 13/16 AF corresponds to a 7/16 Whitworth size and is equivalent to a 21 mm metric socket, spanner or wrench size. My B44 has a skid plate fitted and so I can't tell whether a full length box spanner would fit past the down tube but, if not, you can always reduce the length of the box spanner to fit in sideways (1" length?) and drill a tommy bar hole in it to allow you to rotate it in order to unscrew the pressure relief plug.

[B44R Victor]

Thanks Spaceman.  A friend helped me do just that and it worked fine.  And I'll put the modified spanner somewhere safe so it'll not get lost for next time.  Replacing the valve did the trick.  Much improved flow of return oil back to the tank now and the rockers are much quieter!

Surprised that so much is hanging-onto that little spring and ball.  The sludge around the scavenge valve is already clearing.

Rupert Ratio - you missed this one!

[Spaceman]

Glad you managed to unscrew the plug and replace the spring. Not sure why the B44 plug was recessed into the crankcase in the way it was making it difficult to unscrew - on a B40, for example, you can easily get a spanner on it from the side?

It's not a bad idea to replace the spring as the original could be 55 years old. In principle, a weak spring will reduce the oil pressure to the big-end bearing although this is not as critical as it would be for an engine fitted with a plain bearing.