The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: 7iain7 on 22.06. 2025 14:34
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I’ve completed the engine rebuild. It took a little longer than expected due to a shoulder injury, but it’s finally done.
I have one question: do I need to prime the oil pump before starting the engine for the first time? If so, what’s the best method to do it? I would like to make sure there's oil circulating before starting the engine.
Many thanks,
Iain
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make sure you have oil flowing to the crankcase connection then connect the pipe, take out the pressure relief valve and remove the spark plugs then kick it over or put it in gear and push it until oil comes out where the pressure relief valve fits then you should be good to go. if everything is working as it should oil will be returning to the tank in about 20 seconds
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Getting oil to flow to the engine isn't usually a problem. As Berger says, take out the pressure relief valve and turn the engine over on the kickstart until oil flows out of the PRV housing. Getting the oil to return is, in my experience, a bit more difficult. I pour a mug of oil into the crankcase via the tappet cover. I connect a short length of tube onto the 'R' connector on the crankcase and fill it with very light oil, maybe ATF which is usually red in colour. Turn the engine backwards very slowly until the ATF is drawn down into the pump. Then turn the engine forwards to see the ATF ejected, followed by the fresh oil from the sump.
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Add the oil via the rear tappet cover, this will work its way down to the camshaft trough, so cam and followers will have plenty of lubrication come what may. Injecting oil via the central hole in the PRV cavity feeds lube to the timing bush and then to the big ends, it won't feed back into the delivery side of the pump if the anti wet sump valve is sealing properly.
Turning the engine backwards as suggested will draw oil back down into the return side of the pump, but will need the ball valve in the sump held open to ensure oil goes all the way through the pump. Not easy if single handed, but worth doing to ensure delivery and return systems are primed.
Back in the day folks just connected up the pipes, kicked it over and put faith in the Almighty.......Nowadays I reckon we're all a bit more cautious.
Swarfy
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If the engine has been recently rebuilt there should be sufficient oil to seal the pump and protect areas prior to pumped oil reaching them. If the engine was rebuilt many weeks ago or longer then follow advice for priming.
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Just do what Armory Road did.... lube on assembly, add fuel and kick.
Keep an eye on the oil return though.