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Feb 22, 2019 - 9:49AM

Oil Pump, Scavenging, Wet Sumping

Has anyone had an oil pump that isn't scavenging enough thereby causing a permanent wet sumping situation?

If an oil pump wasn't scavenging to full effect what would the remedy be, would a new Oil Pump Body be the answer?

Is there any test regards the amount of oil that should be returned in a specific time.

Have change timing side cover for NOS with new spring and Ball Bearing, have taken Oil Pump off and cleaned it up.

Any advice suggestions and thoughts appreciated

JohnB

Feb 23, 2019 - 12:01AM

Re: Oil Pump, Scavenging, Wet Sumping

Hi John,
What is the symptom that makes you believe that the pump isn't working properly?

Feb 23, 2019 - 8:56AM

Re: Oil Pump, Scavenging, Wet Sumping

Matty Leahy

Hi John,
What is the symptom that makes you believe that the pump isn\'t working properly?

Hi Matty

It's the continual wet sumping on this particular bike that I have been unable to resolve,

As I mentioned I fitted a new old stock timing side cover with new spring and ball bearing, that did not resolve the issue, took the pump off cleaned it and re
fitted it, still wet sumping.

I have resorted to drilling & tapping then fitting a small allen bolt up the centre of the sump bolt so that I do not have to keep removing the sump bolt to drain the sump.

When I drain the sump and leave a container underneath and come back the next day I find it has eventually stopped draining ( I did not measure the oil in the container, will have to next time!)

Looking into the oil tank whilst the bike is ticking over you can see oil bubbling out of the return .

I thought if the timing side pressure valve ball bearing and spring were operating ok, was the oil either just draining through worn pump body gears (if that is possible) or was the pump not scavenging efficiently.

All very interesting !!

John B

Feb 23, 2019 - 9:42AM

Re: Oil Pump, Scavenging, Wet Sumping

If the engine is wet sumping badly then I would expect too much oil in the crankcase would cause the flywheels to fling excessive amounts of oil up in the bore and cause blue oil smoke out the exhaust. Also oil would normally be forced out the breather pipe as the crankcase is pressurised with excess oil. The oil in the tank must be disappearing also. A faulty check valve would be more a problem when the engine is not running as oil will slowly drain from the tank past the valve into crankcase overfill and will eventually seep through the main bearings and overfill the primary case. The oil return pipe should be a constant flow, or rather a dribble and as the scavenge side of the pump catches up some spirts of air would be normal. The scavenge or return side of pump has a greater capacity than the delivery side to prevent oil build up. Maybe check return line to see if there is a restriction slowing down the oil return.

email (option): tknalder@iinet.net.au

Feb 23, 2019 - 10:02AM

Re: Oil Pump, Scavenging, Wet Sumping

John,
From your first post I thought that you were having issues with wet sumping while the engine was running because you stated "oil pump that isn't scavenging enough". if this is the case there are various causes with different symptoms. Just not sure now that you meant when stationary because you refer to draining oil?

Feb 23, 2019 - 10:28AM

Re: Oil Pump, Scavenging, Wet Sumping

Kim NALDER

If the engine is wet sumping badly then I would expect too much oil in the crankcase would cause the flywheels to fling excessive amounts of oil up in the bore and cause blue oil smoke out the exhaust. Also oil would normally be forced out the breather pipe as the crankcase is pressurised with excess oil. The oil in the tank must be disappearing also. A faulty check valve would be more a problem when the engine is not running as oil will slowly drain from the tank past the valve into crankcase overfill and will eventually seep through the main bearings and overfill the primary case. The oil return pipe should be a constant flow, or rather a dribble and as the scavenge side of the pump catches up some spirts of air would be normal. The scavenge or return side of pump has a greater capacity than the delivery side to prevent oil build up. Maybe check return line to see if there is a restriction slowing down the oil return.

Hi Kim

Thank's for the reply and suggestions,

Due to the wet sumping the bike will not kick start, can't get the momentum going. (I'm no lightweight)

The bike does not burn oil when running. (using straight 40 oil)

No excess oil in Chain Case.

Will check the return pipe to make sure it is clear, will observe the return flow more clearly.

I will accurately mark the level of the oil is in the oil tank, then measure what drains out the sump, also see if and when it actually stops draining.
I think I need to be a bit more precise with my checks!

John B

Feb 23, 2019 - 10:32AM

Re: Oil Pump, Scavenging, Wet Sumping

John I assume that when you took the pump off (great fun when the engine is in the frame) That the little ball at the bottom was free and seating.
This is a pump that I recently removed from a friends engine, the little pick up spout had dropped out and I saw another one like this in Reigate a few weeks ago. Both were replaced with a new bottom plate from Russell's.

However if it's wet sumping whilst stood for a period, I would still double check the easy to get at ball in the timing cover again. Squirt out the seat with WD40 and an airline and check with a torch for debris or Cosmoline, maybe fit a new ball and give it a short sharp tap with a small hammer and thin drift to eradicate any imperfections in the seat.

Or buy a Matchless and just assume draining the crankcase as a weekly task:confused: Ron

email (option): ronpier@talk21.com

Feb 23, 2019 - 11:01AM

Re: Oil Pump, Scavenging, Wet Sumping

If it still wet sumps after you have tried all this then fit an external valve. I have had one fitted to the super rocket for over 20 years and very pleased.
https://www.ebay.co.uk/itm/BSA-M20-21-C11G-C12-ANTI-WET-SUMPING-VALVE-STAINLESS-MADE-IN-ENGLAND/401712233139?hash=item5d87ea3ab3:g:LN4AAOSw8GhZgb65:rk:3:pf:0

Feb 23, 2019 - 12:52PM

Re: Oil Pump, Scavenging, Wet Sumping

Oil can drain through a worn pump and to prevent it draining into the crankcase there is the anti drain valve in the timing cover (1/4" ball) and the ball in the tube mounted to the pump base plate...This ball is 7/32" diameter and is retained in the tube by a small wire clip....There is no spring fitted here...

After carefully removing the wire clip (it's a bit fiddly and will require snipe nosed pliers or possibly tweezers) the ball can be removed and inspected for any corrosion which might compromise its ability to seat correctly...The internal diameter of the tube is 9/32" and the seat for the ball can be cleaned up/refaced by inserting a new 9/32" diameter drill into the tube and turning it carefully by hand whilst applying light pressure...You should be able to see the result of this work...Reassemble the ball and clip in reverse order and give it a try...

If when the pump gears are fitted to the pump body after the pump has been lapped in it is noted there is now a height difference and the gears sit below the surface of the pump body, the body can be refaced using emery paper on a flat surface until the clearance after the end plates are refitted is minimal....Ian

email (option): ian@wright52.plus.com

Feb 23, 2019 - 3:10PM

Re: Oil Pump, Scavenging, Wet Sumping

Ian Wright

Oil can drain through a worn pump and to prevent it draining into the crankcase there is the anti drain valve in the timing cover (1/4" ball) and the ball in the tube mounted to the pump base plate...This ball is 7/32" diameter and is retained in the tube by a small wire clip....There is no spring fitted here...

After carefully removing the wire clip (it's a bit fiddly and will require snipe nosed pliers or possibly tweezers) the ball can be removed and inspected for any corrosion which might compromise its ability to seat correctly...The internal diameter of the tube is 9/32" and the seat for the ball can be cleaned up/refaced by inserting a new 9/32" diameter drill into the tube and turning it carefully by hand whilst applying light pressure...You should be able to see the result of this work...Reassemble the ball and clip in reverse order and give it a try...

If when the pump gears are fitted to the pump body after the pump has been lapped in it is noted there is now a height difference and the gears sit below the surface of the pump body, the body can be refaced using emery paper on a flat surface until the clearance after the end plates are refitted is minimal....Ian

Hi Ian, Ron, Dean, Matty, Kim.

Have kicked bike over today and there appears to be nothing wrong with the oil return flow, see film clip. (I Will not mention the Carb I think it need overhauling or replacing!!)

Will let the bike stand till tomorrow (24hrs) and check what oil is in the sump

As Ron said, I will check the timing side Ball valve again, As Ian said, I will remove the pump and check the ballbearing and replace it.

OIL FLOW

Feb 24, 2019 - 8:45AM

Re: Oil Pump, Scavenging, Wet Sumping

Yep, oil return looks normal.

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