help-a7ss

[rocker21]

i rebuilt my a7 with new everything and i mean everything, including an SRM oil pump, bike has done nearly a 1000 miles without problems, went to a local steam rally last weekend  it was 31 miles to get there, got there without problems, on the return trip all was fine when i stopped to fill up which was approx 13 miles from home, got home and i was covered in oil and so was the bike so much so that i could not see where it was coming from, gave it a wash after it had cooled down and after much puzzling the oil was coming out of the breather and going over the gearbox sprocket and chain and getting chucked everywhere, turns out oil was going into the engine but not going back to the tank, it has an external oil filter fitted in the return line, so drained what was left in the oil tank and removed the pump, put an air line on the hole going back to the tank and it blew the oil in the filter into the tank, so that was clear, removed the sump plug and a very large quantity of oil came out, removed the sump plate and there was nothing on the gauze filter put the air line on the sump pickup and it blew clear. all the oilways blow clear so i am puzzled as to why the oil was not going back to the tank.
the oil pump appears to be working as it pumps when you turn it by hand,
so anyone got any ideas as to why the oil was not going back to the tank.

[Greybeard]

Is it possible that you had topped up the tank while oil was in the sump? I made that mistake ONCE! . The symptoms were exactly as you describe ☹️.

[CheeserBeezer]

Maybe the ball in the pickup had stuck. You've cleared it with the air line. The ball seats on the bottom of the suction pipe and should not close the oilway when it starts to suck, by way of a split pin through the pipe above it; hopefully this arrangement is still OK but, if something has gone wrong,  there is a slim chance the ball is closing the oilway as the pump starts to suck. Maybe put everything back together, remove the return pipe from the oil tank and check oil is coming out. Check the oil pump hasn't come loose? is the bike plunger or swinging arm? The oil suction pipe fitting into the crankcase differs between the two. It is possible the suction pie has come loose in the crankcase - hope not as that would be a strip-down. Check the gasket behind the pump to make sure the pump isn't sucking air. Just some ideas, hope you find what the problem is.

[rocker21]

did not top up the oil tank, brand new SRM pump and fitting kit and all the bolts were tight, the only thing i can think of is the ball in the sump pickup, but why would it fail while out on a ride?  and as it had already done a few miles that day without problems.
its a 1960 A7ss with a very non standard engine. been working with the pre unit A group stuff for many years.
it does not wet sump when stood for a few days or weeks.

[Triton Thrasher]

Maybe unlikely, but did you fit a magnetic sump plug under or near the scavenge pipe?

[rocker21]

yes it has an alloy sump plate with a magnetic drain plug

[Triton Thrasher]

A magnet near to the end of the pipe can make the ball stick in place.

So I’ve heard.

[chaterlea25]

Hi All,
Yes the ball will stick if the magnet is fitted near the pickup,  been there !!!
I replaced the magnet with a weaker one on a BSAsingle as I could not move the magnet far enough away.
On the A series fit the plate with the magnet furthest away from  the pick up
The magnet is epoxied into the plug, some heat will soften the epoxy and the magnet can be pulled out if you want to replace it

John

[rocker21]

i can give that a try as i can turn the sump plate round

[muskrat]

G'day rocker.
The motor has done 1000 trouble free miles I doubt the problem is the magnet. It would have caused problems right from the get go.
Have you tried it from cold? If it's OK cold and happens when everything is hot check the routing of the hoses to and from the filter, they may kink when hot.
 The pickup pipe may have come loose in the case. Try propping the ball up with a pin, put a good fitting hose over the pipe, finger over the hole to pump and suck on the hose. It should hold vacuum. Again it may hold cold but not hot as the alloy crankcase expands away from the steel pipe.
It's a real  problem.
Cheers

[RichardL]

R21,

This wouldn't apply to you, based on the successful miles, but I once experienced lack of return after a slow rebuild and was also baffled as to how this could be (that is, the slow return, not the slow rebuild). Finally, pulled the oil pipes from the engine to find a spider's egg sack in the return. I can't really expand more on the rational possible causes for your issue, because they've been well laid out. One thing though, I try to check for oil return every time I start the bike. I think I remember to do it 90% of the time. So far, the other 10% hasn't kicked my ass.

Richard L.

[Swarfcut]

 Anything which impedes the return of oil to the tank will give those symptoms. For starters everything has to be checked from the sump ball valve to the return line in the tank and its outlet hole. Any restriction past the T off to the rockers means oil will circulate back into the engine rather than back to the tank, and when this volume becomes greater than the scavenge capacity it is then discharged from the breather.

 Consider the problem as two scenarios....A fault in the pick up, causes include leaks or component failure, and a fault with the circulation, typically a restriction or blockage. A direct connection to a slave catch tank will give an idea of how well the return side is working. Musky's test will prove a sound connection to the pump. A loose, failed or leaking pick up pipe could be changed without splitting the cases (with a bit of guile and skill) on S/A motors. Alas not so simple for the Plunger community.

 The sump ball valve sticking shut was a known problem even back in the day. I suppose the ball and its seating don't last forever, but a good wash out with carb cleaner is worth a go. Lots on the Forum about this pesky valve and associated oil in the wrong place problems....ask RD!!

 Swarfy.

[rocker21]

thanks for all the info, all the oil lines blow clear with an air line including the one back to the tank via the filter as it blew the oil in the filter back into the tank, it seems the most likely culprit is the ball in the sump pick up. will give it a wash and put it back together with a new filter and see what happens.

[chaterlea25]

Hi Musky
The problem I had happened about a year after the magnetic sump plate was fitted!!
 I have no idea why it took so long to happen ???

John