The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Beezageezauk on 21.02. 2010 06:54
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Hi Guys, Does anybody know if it is possible to bench test an A7 oil pump? I'm working on an engine that doesn't wet sump when stood but wet sumps when running. I've checked the scavenge pipe and the oil pressure release valve and these seem to be ok. Any ideas or suggestions please??
Cheers.
Beezageezauk.
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Hi Beezageezauk, just a thought, but i`m sure i remember someone here who had a similar problem that turned out to be a sheared off gear on the scavenge side of the pump. Had a quick search for it but couldn`t find it, might be worth a look?
regards Rich.
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Thanks Rich, I'll see if I can find it.
Beezageezauk.
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Found it! *smiley4*
http://www.a7a10.net/forum/index.php/topic,885.0.html (http://www.a7a10.net/forum/index.php/topic,885.0.html)
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Also have a real close look at the cases.
It is not unknown to have cracks between the oil holes which naturally open out more when hot.
Also check the mounting holes occasionally one of them was machined too close to the oil galleries and over time develope cracks.
If such a bolt hole has been helicoiled then you can be 100% sure that it will have breached the oil holes and as such will not pump the oil back to the tank. just out of the sump into the bolt hole and back to the sump again.
Also check the standpipe in the oil tank for good flow. We used to pinch them off to create more back pressure to get more oil to the head and I have seen bikes wher this has been taken to extreames such that 80% ,of the scavenged oil goes up to the head and then back to the sump, thus emptying the oil tank into the sump every 1/2 hour or so.
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See Pooch's post on the BSA Forum.
His solution is to rotate the sump plate - seems it was blocking the pump suction pipe.
David