Timing side anti-syphon valve

[nigeldtr]

Hello

I am just rebuilding the bottom end of my plunger A10 and I have been advised to clean out and check the anti-syphon valve in the timing side crankcase half, can anyone explain to me what this does?

thanks

Nigel

[a10 gf]

Prevents oil emptying from tank to crankcase when engine not running.

Ball stuck \ oil channel blocked = oil starvation.
Spring too loose \ ball not seating properly = wetsump.

[RichardL]

If you haven't already found it, it's behind the oil pump in one of the holes. (Which one, I can't recall right now and no books available while sitting on a plane at the gate.) Poke something in the holes to discover which has a ball and spring in it. You won't be able to service it unless you plan to split the cases. Make sure it's springy. Spray some carb clener in the hole. While I'm thinking about it, it would be interesting to know if anyone has measured the force it takes to compress a new spring a particular amount, and how they did it.

Richard L.

[dpaddock]

Great photo! Thanks.

David

[nigeldtr]

Thank you for the picture - does anyone have a drawing/sketch of the oil ways as I would be interested to know where it "sits" schematically?

Regards

Nigel

[a10 gf]

Here's a picture: http://www.a7a10.net/BSA/techpics/oilflow.jpg , & see http://www.a7a10.net/forum/index.php/topic,454.msg2363.html#msg2363 , plunger owners manual.

[BSA_54A10]

Buy a 1/2 dozen springs.
Put them in a bag with a label so that you will remember what they are.
Ever time you pull the pump replace the springs.
Every second that your engine is running hot oil is being drawn through this spring.
A spring is only springie because of the heat treatment that it gets.
With time this spring looses it's proper temper and when it dose you will wet sump.
If you wet sump bad enough there will be no oil in the pump when it starts to spim which is not good for the pump or the rest of your engine.

[muskrat]

G'day Trevor,
                      wise words, but don't the cases need to be split to change the spring? On A65's it's behind the pump?
Cheers

[Triton Thrasher]

Ever time you pull the pump replace the springs.
Every second that your engine is running hot oil is being drawn through this spring.
A spring is only springie because of the heat treatment that it gets.
With time this spring looses it's proper temper and when it dose you will wet sump.

None of my engines get that hot.  Even the exhaust valve springs are still springy.

[chaterlea25]

Hi All,
My 2 cents worth is if you have the engine apart modify the anti drain ball /spring to the A65 system
I have posted pictures of this before, then its an easy job to "service" the anti drain

John