Author Topic: More wetsumping  (Read 5255 times)

Offline A10Boy

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Re: More wetsumping
« Reply #15 on: 20.11. 2009 18:08 »
Are you sure you have a good return to the oil tank?

I cant see how you can have both a good return to the oiltank AND a pint of oil in the sump, unless the oil is breeding!

John is correct, the scavenge side of the pump has a higher output than the supply side, so the sump should never fill while the engine is running.

Maybe you have a cracked pump, or duff pump gasket, which is letting the pump cross-over the flows so that [some of] the supply oil is pumped into the return oil way and the oil which should return to the tank is just staying in the sump. - have you checked the pump and gasket?
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline Rusty nuts

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Re: More wetsumping
« Reply #16 on: 20.11. 2009 20:42 »
this is why when you start the engine after sitting for a while the return flow is constant until the sump clears!
Err, and then the flow is not constant? That would worry me. There has to be oil in the sump for the scavenge pipe to "scavenge" it.
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Online bsa-bill

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Re: More wetsumping
« Reply #17 on: 20.11. 2009 21:14 »
NO - as Andy has said the scavenging side has greater capacity then the feed side therefore it pumps what oil is in the sump and a certain quantity of air which is also present in the sump, this results in a intermittent (spluttering) return into the oil tank.
Also means the sump should be almost empty when the engine is stopped other than oil that is clinging to surfaces inside the engine, drains down from the rockers and I suppose anything that slurps (nice word that) over the camshaft through when the bike is hauled onto the stand.
The amount that drains down from the rockers is of interest, I assume there is a limit to the amount that will pass past the cam followers in any given time, if the rockers are over fed then there could be a build up in the pushrod tunnel giving rise to symptoms similar to those described  but it's not one I've heard of before.

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline dpaddock

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Re: More wetsumping
« Reply #18 on: 21.11. 2009 15:37 »
FWIW, I get 135 ml (~1/2 pt) two minutes after engine shutdown, and 175 ml after 24 hrs in my A10.

David
David
'57 Spitfire


Online RichardL

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Re: More wetsumping
« Reply #19 on: 21.11. 2009 19:49 »
In the cousre of time, some old posts are forgotten or unknown. I hope the video linked to this previous post of mine is useful in seeing the sputter versus flow nature of the oil return. Nevertheless, It gives me a chance to show the bike to peolple who know what they're looking at, a quite rare commodity in my neck of the woods. (Groily, I think I may have already apologized for shininess.)

http://www.a7a10.net/forum/index.php/topic,1129.msg8220.html#msg8220

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline alanp

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Re: More wetsumping
« Reply #20 on: 21.11. 2009 20:43 »
Richard, I've just noticed the chromed hubs front and back. Haven't seen that before. Maybe I should get out more?
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Online chaterlea25

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Re: More wetsumping
« Reply #21 on: 21.11. 2009 21:41 »
HI
dpaddock,
When I went to school there were 568ml (cc) in a pint
so 135ml is less than 1/4 pint, 175ml just over
This is the amount I would expect
HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Rusty nuts

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Re: More wetsumping
« Reply #22 on: 21.11. 2009 21:57 »
NO - as Andy has said the scavenging side has greater capacity then the feed side therefore it pumps what oil is in the sump and a certain quantity of air which is also present in the sump, this results in a intermittent (spluttering) return into the oil tank.
Also means the sump should be almost empty when the engine is stopped other than oil that is clinging to surfaces inside the engine, drains down from the rockers and I suppose anything that slurps (nice word that) over the camshaft through when the bike is hauled onto the stand.
The amount that drains down from the rockers is of interest, I assume there is a limit to the amount that will pass past the cam followers in any given time, if the rockers are over fed then there could be a build up in the pushrod tunnel giving rise to symptoms similar to those described  but it's not one I've heard of before.

All the best - Bill

Sorry Bill I have to disagree, If the sump is almost empty except clinging oil you'd have a serious problem, more than likely a seized engine, it is not only the big ends etc that require oil, the camshaft (certainy long stroke engines as they do not have a trough) & more importantly cylinder bores rely on oil throw/pressurised mist from the crank, without it they'd seize.
Also acts as a coolant.

These engines are designed to be pressurised to a point (hence timed breathers) to enable oil to lube aforesaid & oil control rings are there to prevent that oil progressing into the head itself.
Spluttering from the return is proportional to engine/oil pump rpm. At tickover it splutters, at higher revs it'a constant flow.

Short of us all going for a ride, draining our sumps into our wives finest measuring jugs & establishing an average I would say anything from 1/4 to 1/2 a pint acceptable.

But we digress, getting back to the point, I think Groily has the most plausible explanation, rings, or as my earlier post, rocker feed bolts with dirty great holes & its flooding through the valves & into the head. I'd put money, if I wasn't so tight on Groily's theory.

Anyway enough of this I'm off to wet sump with a few a few pints of Fullers finest.
For those not familiar, think heavy monograde, lubricates well, relieves stress from vital components, but can cause difficulty starting of a morning *beer*
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Online bsa-bill

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Re: More wetsumping
« Reply #23 on: 21.11. 2009 22:02 »
Hi John, are you remembering Davids US pint is a tad smaller than ours  *smile*

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online bsa-bill

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Re: More wetsumping
« Reply #24 on: 21.11. 2009 22:23 »
Ah now Rusty Nuts, I'm not at all sure about this, now matter how many revs you have, the scavenging side MUST always have more capacity than the feed side.
So if at any point in time the feed is delivering more oil than the return side can take away something is wrong with the pump or it's plumbing.
If the return side did not always pump more than the feed side then there would come a point when the sump would fill to a level that would stall the engine or worse the sump would contain all the oil and starve the feed side, however before this happened you would notice the smoke screen in your mirror!!!.
I would suggest that at higher revs it will LOOK like there is a constant flow but in fact there never can be, it would simply be to dangerous to have a situation where both sides of the pump produced equal flow.
I agree that the sump will contain oil after the engine has stopped, this will be the oil that is splashed about and then runs down the case and so on as you say, but at the moment you touch the kill switch the sump should be next to empty.

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Rusty nuts

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Re: More wetsumping
« Reply #25 on: 22.11. 2009 10:16 »
Bill, I think we are arguing over semantics here.
Bsa service sheet 116 I believe re PRV  begins "in order to maintain a contant flow to the white metal big end bearings........."
I didn't (don't) dispute the fact the "system" has a greater scavenge capacity, ergo, if the feed is "constant" then the return must also be.
On that point I believe we are singing from the same hymn sheet, just to a slightly different arrangement!

The only point of contention is how much oil collects or should I say is present in the sump between delivery & collection.

I am happy with my residual half pint, it may be a wee bit less, I don't measure it, just use a big 1pt yogurt pot & judge by eye.
I'm sure a 1/4 pint is fine too.
I would not buy a bike that had a "next to empty" sump.

I've started mine after standing for several weeks having forgotten to drain & based on what comes out when I do remember after such a time period
there must have been close to a pint, but engine coped without throwing oil out of timed breather, creating smoke screen etc.

Sure hope Blackbikemike resolves his problem shortly as this thread is heading off at quite a tangent.

Cheers

Rusty
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Online bsa-bill

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Re: More wetsumping
« Reply #26 on: 22.11. 2009 10:40 »
Hi Rusty - I prefer the word discussion than argument  *smiley4*

My Flash smokes when fired up and not always the same side but clears after a couple of hundred yards,  this I put down to the amount that drains down after stopping, must have a look and see how much there is.
Could be a bit of wetsumping too as I don't get to ride it as often as I would like, despite retirement.
However when I think of wetsumping I think back to my very first Flash that once but only once dumped a half pint or so onto the ground via the breather exit, it had been standing idle for weeks though.
I don't think a bit of smoke at start up is a worry if it is the result of oil collected in the sump getting burnt off after startup, I can remember when advice was given to the effect that good practise was to take your foot off the accelerator going down hill in order that oil would be sucked up into the cylinders for extra lube.
There again I can remember when garages always had a Redex dispenser by the pumps - I'm off now ( beginning to sound like an old F*** ) 

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Rusty nuts

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Re: More wetsumping
« Reply #27 on: 22.11. 2009 11:08 »
"arguing over semantics" is just a turn of phrase Bill
There are no arguments here, just healthy discussion
that's what sets this forum apart from some others.
Now then, smoking at startup is I believe caused by........................................ *smile* *smile* *smile*
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
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Online Triton Thrasher

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Re: More wetsumping
« Reply #28 on: 22.11. 2009 17:37 »


These engines are designed to be pressurised to a point (hence timed breathers)

I think timed breathers are an attempt to stop the crankcase pressurising.

Offline Rusty nuts

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Re: More wetsumping
« Reply #29 on: 22.11. 2009 17:52 »
If that's the case why run at half crankshaft speed not full?
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V