AJS G8 1926 - Oil pump question

Information relating to Matchless and AJS Models built prior to 1939
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Greybeard
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Joined: Mon Jun 29, 2015 8:49 pm
Location: East Yorkshire

AJS G8 1926 - Oil pump question

Post by Greybeard »

My G8 has two oil pumps. One is the Pilgrim pump with sight glass on the timing case that pretty much takes care of itself, the other is the manual pump mounted on top of the tank. I know this one is to be used when giving the engine some beans or on a long, uphill slog. The good book also says that three or four pumps will also be sufficient to top up the sump when the old oil has been drained off.
My previous experience of these pumps is with a 1920s Francis Barnet. With that one when you pushed the pump down it sucked up a fill of oil which the spring return plunger then delivered to the engine in a slow feed. Pushing down this one, its not picking any oil up and gives no more than a derisory spit from the feed pipe.
Ive stripped it to makes sure that the leather cup washer is facing upwards and in good condition and also that the gland seal around the pump rod and the small ball bearing valve in the feed elbow are present.
What am I failing to see? :oops: The way its made suggests that the 'vacuum' created above the cup washer when its pushed down should pull oil past the cup and fill the barrel. Apart from a gauze strainer over the pump end, everyhing shown in the parts list is there.
Thanks in advance.

Steve
Greybeard
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Posts: 456
Joined: Mon Jun 29, 2015 8:49 pm
Location: East Yorkshire

Re: AJS G8 1926 - Oil pump question

Post by Greybeard »

I may have identified the problem - amazing what knocking off for a brew can do :roll: I think theres a slight leak on the oneway ball valve thats preventing it making a proper vacuum. I can now get it to suck up oil when the tap's shut but not when its open. Some judicious tapping of another ball against the seat might be called for. Im assuming that it has the correct size ball bearing in there of course. Other than the parts list telling me that a new ball valve with spring and blanking screw is 5d, theres no email address for paypal :|
Anyone happen to know how big my ball should be?

Steve (wot might even get to ride a G8 soon)
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Rob Harknett
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Location: ESSEX UK

Re: AJS G8 1926 - Oil pump question

Post by Rob Harknett »

Greybeard
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Posts: 456
Joined: Mon Jun 29, 2015 8:49 pm
Location: East Yorkshire

Re: AJS G8 1926 - Oil pump question

Post by Greybeard »

Ive got that one thanks, Rob, though it doesnt really cover the pump Im referring to. I think Ive sorted the problem. I looked at the ball bearing under a magnifying loupe and found some very minor pitting that seems to have been enough to allow air back into the system. A new ball (its a 3/16th by the way) and a flow has been restored.

Steve
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