The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Steverat on 27.03. 2019 12:00
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Josef’s bike has got into the habit of dumping a load of oil on the road and failing to return to the tank- only intermittently but badly enough to empty the tank. I think and hope I’ve found the cause - the little non-return valve in the sump pickup jams shut from time to time. Anyone else seen this problem?
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A much later bike but I am sort of hoping that is the cause on my 1960 A10. See my 'where has the oil gone' thread here https://www.a7a10.net/forum/index.php?topic=13251.msg106487#msg106487 (https://www.a7a10.net/forum/index.php?topic=13251.msg106487#msg106487). I am about to try her again, but if that is the cause what is the cure.
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Wiser heads than mine will help shortly but do either of you guys have a magnetic sump plug fitted as they have been the cause of this problem before if you've fitted the plug nearest to the pickup , worth a check .
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I could envision some kind of crud (maybe very old) between ball and sidewall of tube jamming the ball with only suction applied, but appearing free when pushed by hand.
Richard L.
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I have magnetic sump plug. Its been there since I bought her 4+ years ago. Its not the normal one as it in the centre of the sump plate so should not cause the problem and has not until last august and last week. It may not be this, I have given it a good clean and am just setting up to run a test with the sump pate off and a pipe extending the scavenge into a jar of oil. If the oil drains as I expect I will put her back on the road and monitor the situation.
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Hi All,
I would try to see if the ball has become magnetised ?
Try and find a small piece of steel that is not magnetised, see will some steel filings stick to it to check (Make sure to clean it afterwards)
Then see will this piece of steel stick to the ball or pickup pipe
If you find the pickup or ball is magnetic then next question is how to demagnetise it *????* *????*
John
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I am told that passing an AC current through the item will de-magnetize it. Don't ask me how! Alternatively a de-magnetizer can be got from that well known auction site on line.
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........... I have given it a good clean and am just setting up to run a test with the sump pate off and a pipe extending the scavenge into a jar of oil. If the oil drains as I expect.......
I understand what you want to do and expect it offset so as to not catch any from the sump in the jar, but why have oil in the jar? Wouldn't an empty jar be better ?
I also can't see that the scavenge pipe wold dump any more than what is in it alone, which isn't much anyway.... the way I see it, a sticky ball allowing any bleed-down would only reduce the potential self-primed action and try to suck air which I doubt... *dunno*
Best way I can think of is to pull the pump off and blow air down the scavenge hole
** Edit; having just read Bergs's post (20sec after mine), also run some solvent down from the top a couple of times before/during/after the air b
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I have not been to the pub! haha i can't resist this answer *fight* I demagnetise things that shouldn't be magnetic by bashing them about and giving them some hammer *bash* *bash* *bash* *bash* *bash* *bash* *bash* *grins* *evil* on a more serious note its a long time since I had to play with my ball *shh*, but once pushed up is there enough room to try and clean it out a bit with petrol and a well made artists brush or something like that *dunno*
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I think we can take it as read that Steve has cleaned all parts of that engine.
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If the ball is found to be magnetic,it is worth trying a little heat to upset the magnetic domains within the metal. Not too much heat, the ball housing is brazed to the pick up pipe, so a hot air gun would be a good start.
This will also melt any hard deposits lining the housing.
An alternative thought is that with new, thick oil and a new Super Suck Pump the ball is being drawn to the top of the housing, blocking the pipe, then innocently dropping back down by the time the motor has cooled and the sump plate is off. There needs to be space around the ball for the oil to get by. So a crud lined housing could be the problem.
Carb Cleaner Spray and Nail Varnish Remover/Acetone are a couple of solvents to try....wedging the ball up and leaving it to soak in a small container overnight, for example. Then a good poke around inside to pull out any solids.
But if, as GB says, everything is clean then this becomes more of a mystery of the universe, and changing the pick up pipe an annoying prospect.
Hope it is a bit clogged, if not, maybe worth trying thinner oil, but clutching at straws a bit here.
Swarfy.
Additional. This got me thinking and I have just checked a couple of pick up pipes, and in each case the ball hardly lifts off the seat before being stopped by something in the housing. It comes to rest just 3mm from the flat face of the ball housing, not leaving much space for oil to pass the ball.
I have never had a valve apart, but Roy Bacon's diagram on page 93 in my copy of BSA Twin Restoration would indicate the ball can rise a fair distance. So either the book is wrong, or I have a problem looming.
Anyone with a sump plate off to compare how these valves are set up? Anyone successfully running without the ball?
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"Additional. This got me thinking and I have just checked a couple of pick up pipes, and in each case the ball hardly lifts off the seat before being stopped by something in the housing. It comes to rest just 3mm from the flat face of the ball housing, not leaving much space for oil to pass the ball.
I have never had a valve apart, but Roy Bacon's diagram on page 93 in my copy of BSA Twin Restoration would indicate the ball can rise a fair distance. So either the book is wrong, or I have a problem looming.
Anyone with a sump plate off to compare how these valves are set up? Anyone successfully running without the ball?"
I had to replace the end of the suction pipe on a bike I built recently. (Some P.O. clown had sawn the tip off and removed the ball!) On close inspection the pipe should have a wire across the inside of it which prevents the ball closing the pipe. It's difficult to see this from the outside but if you cut the enlarged piece of the pipe, which holds the ball, off you can see the metal bar from the other side. It is shaped so that the ball is held to one side. The bar is quite flimsy so, if it got damaged or fell out the ball would block the pipe. Similarly, if somebody hit the ball upwards, maybe with a punch or rod, thinking this was good thing to do to free it off (!!!!) the wire bar would break and the ball would contact the narrower pipe at the top and probably block it off. Not sure if this is helpful. Picture attached.
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Andrew Thanks for shining the light.
I (and probably most of the rest of us) have never really considered that the valve was anything more just a ball in a hole. This could be the answer to many instances of scavenge failure.
How BSA actually made it and ensured the bar/ wire stayed in place during brazing is a fine piece of production engineering. Roy Bacon's diagram looks to be an over simplification, but the wire is an ingenious way to move the ball to one side to clear the path for oil flow.
In the now clearer scheme of things, looks like Steve's first step is to see how far the ball moves. To the top of the housing, bar/wire missing, not good, possibly blocking the pipe. Jammed down, no scavenge. Moving as intended.....goodness Knows!
Swarfy.
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Photo shows where the bar goes through.
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Julian.. Thanks, as always you make it so simple. I made it very complicated. I assume that in production the bar was added last. Looked at Roy Bacon again and it makes sense. The ball by my estimation should move a fair amount, so looks as if my pipes require attention.
Swarfy.
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... my pipes require attention.
As the Actress said to the Bishop ;)
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in between playing with the gearbox I had a look see at my STILL empty crank cases . I found out I could easily get a piece of 40 thou soft wire past the ball all the way around it and up to the near 90 degree bend I didn't want to force it round the bend because it was ally wire and if I broke it I would have been more than fed up *problem* *bash*
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and if I broke it I would have been more than fed up *problem* *bash*
And then you would have to go to the pub! *eek*
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and then you would have to go to the pub! *eek* well today I am going to the pub , not been since last Friday *good3* i'm getting better at realising one day in the pub costs me two day's not getting things DONE, that's because I am an all or nothing kind of guy, I can't go for a couple--- it has to be - or it ends up being a 10 hour shift *countdown* *help* and trying to get the key in the door about 3am with the house door moving left to right and up and down *eek* *doh* and as older brother say's workshop time is better than PUB time!!, but first I am shedding and concocting a G clamp with attachments to pull in the needle rollers on the rrt2 thingy so when the cases are something like sizzle spit hot if they don't drop in after being in the freezer like good little bearings and behave I won't have to *bash* *bash* *bash* them *sick* . thankyou for listening *smiley4*
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Have posted in my original thread https://www.a7a10.net/forum/index.php?topic=13251.msg116330#msg116330 (https://www.a7a10.net/forum/index.php?topic=13251.msg116330#msg116330). Test went as expected jar emptied and good return to tank.
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Angus, By chance did you note how much the ball lifts into the housing? As I mentioned, there seemed very little gap for oil flow on my valve.
Swarfy.
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I did check it all using this and the other thread. The bar is in the pipe and the ball lifts well away from the bottom probably half way up. Sorry should have done a picture but its back together now. and I am going to try her again today.
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Angus, Thanks for looking. Before esteemed member GB says it, for good health it is always a good thing to check....
Regards.
Swarfy.
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swarfy just looked at A7 ss cases and ball the goes up 3mm ish
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bergs, Thanks for looking. Mine is a definite restriction compared to the lucky folks with the bar half way up the housing. Looks to be some curious variance at work here. Fortunately this motor is currently in pieces, a basket case with all the usual wear, tear and neglect. But as a complete unknown it is a case of checking every part for evidence of why it failed. This faulty pick up pipe could be part of the answer.
Don't get paranoid folks, just check the valve for free movement every time that sump plate comes off. Be interesting to see how other valves are set up.
Swarfy.
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I usually poke a piece of wire up there when I do an oil change and let it drain, and from memory there's not a lot of movement- fairly much just enough for the wire to go up, probably about 1/8", but can't see it needs more anyway
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Josef’s bike has much more freedom of movement for the pickup ball which disappears completely into its chamber when poked with the wire. I had to go over to Germany to fix it last week (bike is now home near Munich) I have left him with strict instructions check return oil flow every time he starts the engine and I think he’ll be alright - I scraped and scraped at the ball until dinner time in my efforts to get the last bit of roughness/corrosion off it which might jam it again. This will probably be my last post since the bike is gone now and back in it’s owner’s care. He took it to the TUV last week and the tester was bowled over apparently. These things can still look attractive to the younger generation, there’s hope yet. In the meantime my next project is on the way. Fraid it’s not a Beeza, just a late T•••••h twin which hopefully is going to take me tourng in Belgium. So long and good luck to you all especially those who have spent so much time and effort trying to help me. And if you happen to be in Ypres in mid May look out for a red and white T•••••h Daytona. I’ll buy you a drink at least. We are staying in the centre so should not be so difficult to spot.
Cheers
Steve