I think I’ve searched everything possible on the forum and still have an unresolved issue so guess I need to post this to the brain trust for help.
I’m nearing the completion of my BSA M20 restoration and have the machine where it will easily start and idle smoothly. But I have no oil returning to the tank. I’ve checked both oil lines for obstruction. Checked the tank vent and that both hose connections on the tank are clear using compressed air. The oil pump filter is clean and the oil pump check ball moves freely. The timing cover check ball and spring are working properly. All passages on the timing cover are clear of obstruction. Oil pump is processing the gravity fed oil from the tank because the sump builds it up. The oil pump is moving oil through the timing cover so engine moving parts are getting oiled. The screw plug between the timing cover and the oil pump shows oil when opened. And I verified everything on the oil pump was clean with it having good gears that can be turned as an assembly with ease. While the oil pump was out, I also blew compressed air down each oil hose to make sure nothing else was blocked in the lower engine area. Having done most things 2-3 times now including pulling the timing gears and the oil pump drive spindle, I’m getting frustrated.
Hopefully I’ve overlooked something simple that I can be reminded of for getting oil back to the tank. And for reference, I’m running SAE straight 30 weight oil right now since I use it in my other vintage military vehicles.
email (option): dgordon4@austin.rr.com
you dont mention it but have you checked the return pipe in the oil tank sometimes can get blocked because of it being fattened at the top end in the tank on my B31 it was blocked with hard sludge and the tank was a quater full with sludge
email (option): roger.beck@node6.com
Might be a silly question but have you got the pipes round the right way.
Yes, I'd also verified the connections into the tank were clear. Blew compressed air through them when I'd checked the lines. I double checked the timing gear and main openings into the engine were clear as well when I'd pulled everything to get the oil pump drive spindle out.
And pretty sure the lines are on correctly. Inside line on the tank goes to the inside of the engine and the outside tank line goes to the outside of the engine.
email (option): dgordon4@austin.rr.com
Hi,David how long have you had engine running for? as sometimes can take a while for oil to return to tank.I would also remove return pipe (outer) at tank if still no return then prime pipe with oil can till full then start engine if it just pumps out the oil you have primed into pipe then check oil scavenge pipe at pump.Also if your engine has the blanking screw under timing cover remove this to see if oil is there, if no sign of oil leave out blanking screw then pump oil into return pipe again using oil can and check for signs of oil.If still no go I would check oil pump and also gasket is in right position and not covering return. good luck Dave..
Latest for today...
Took the return oil line off again to check it and it was free of obstruction and no signs of crimping or anything else that would block it off when mounted. My lines are rubber with the metal fittings crimped at each end as you'd see with high pressure lines on a tractor. They are also known to have been good since before the restoration, I had oil returning to the tank. So sure it is something I did (or didn't do) during that process that has taken roughly a year.
Opened the blanking plug on the outside lower engine under the timing cover and there was some oil that ran out. Left that plug off and the oil return line off for another test start. Both burped some oil so closed off the blanking plug and the oil return fitting burped more. Once I had a decent mess (but not flowing oil) I put the line back on and primed it to the top as suggested. Ran the motor for a good five minutes and shifted up and down through the first three gears a few times just to circulate the transmission oil since the bike is on a stand.
During this run time, there was still no oil coming back to the oil tank. The breather pipe on the engine was dripping by then and built up a small puddle plus splatter so I'm not at risk of the engine being starved of oil. It actually sounds pretty good and is still easy to start and operate. Previous to the first posting I did, I had also removed the timing cover and pressed the kick start lever to confirm oil would spit out of the side of the engine and it did. Just mentioning this since someone might wonder if I’m at risk of locking up my engine running it with no visible oil returning to the tank.
Checked the blanking plug after this last run and there was no oil dribbling out. Have not removed the return line again but I'd be surprised if there was still oil inside of it since it would work its way back out if nothing is pushing up while the engine is running.
Still open to suggestions. Hoping I don't need a new oil pump. Is there any way to remove the pump and test it's suction off the bike? I know the oil pump check ball was free to move as it rolled back and forth with ease as the pump was turned over when off the bike last time I was double checking it. Also don't know how much clearance there is between the oil pickup and the sump pan.
email (option): dgordon4@austin.rr.com
Hi Dave
Just had my pump out and apart to fix a couple of problems. If you rotate the drive cog (anticlockwise if I remember rightly) while immersing the lower half of the detached pump in a dish of oil you will see it make a nice little fountain -if it is working. I used a power drill to provide the motive power.
Cheers
Pete
Hi Dave,
It sounds like the “straw” of the oil tank return pipe is punctured somewhere along the way Under the oil line, so the oil is returning, but you cannot see it.
Did you check it?
please see this:
http://www.mistgreen.com/JimsM20Pg3.htm
It seems like your bike has the same problem..
Good luck,
Noam.
email (option): noam10@gmail.com
Started over with the oil pump and lines again today and still no joy....
I checked the "straw" by blowing compressed air up the return line and it only exits from the top of the stem via the two holes as designed. No bubbles coming into the tank from the bottom under the oil. Figured that would be the case though because I have no oil returning to the tank, although as previously mentioned, it worked fine before tearing the bike down for restoration.
While the oil pump was off yet again, I blew compressed air up the hole in the engine where the pump's return would be and it passed up to the tank with no issues so no obstruction there. Removing the blanking plug from the lower engine side had good air flow coming out when the same test was performed with compressed air from underneath.
Tested the oil pump on a drill in oil. The pickup pipe underneath draws oil and flows it out through the proper hole in the pump when the drill is going clockwise. Counter-clockwise produces oil on the opposite side which should be where it would draw from the oil tank. Already knew the pump could pull though since it sucks down the tank's oil level when the bike is running.
Bolted everything back up, filled the oil tank and started the bike. Still no oil returning to the tank but there is oil in the crank case so once again it would seem to pull but not push oil when mounted to the engine and run.
I checked the blanking plug after a short run on the stand and it had no trace of oil this time. All oil passages seem to be clear so I must still be missing something.
email (option): dgordon4@austin.rr.com
Just read this thread, my only concern was the oil pump anti drain ball rattling up and down as it is turned over. The ball should be held down in place by a very fine lever spring. Is it the right ball? If the ball is not held down by the spring it might flow up to the bottom of the pump when running and block the suction side.
Cheers Pat
Or sump plate blocking the scavenge spigot??
email (option): n.gentner@bigpond.com
In the pickup tube on the oil pump there should be a wire across it to stop the ball rising up too far and blocking the oilpump pickup hole. Make sure it is still there.
Hey Guys,
I double checked the spacing from the pickup tube and the bottom of the sump pan and there is sufficient clearance. Also verified the wire clip inside the pickup is flipped the correct way so that the ball is retained and cannot be sucked up against the lower gears to block them off.
While I had the pump body off this time, I checked the orientation of the lower end fitting of the spindle with a mirror and then kicked the bike over without fuel or starting settings for the levers so it wouldn't fire up. Checked the spindle again to verify it had rotated and I found that it had slipped down roughly 1/8 which should be impossible. Pushing it with a finger confirmed it could move up and down which shouldn't be possible.
I pulled the timing cover and then removed the spindle retaining pin to verify it's ends were OK and they were. Lined everything up and pushed it back in and it seated and holds the spindle as designed. Double checked the manual and searched the forum to discover there should be a washer of some kind to keep back pressure on the retaining pin. So looks like that is probably my problem.
Now to source one of these washers and probably another retaining pin since mine isn't mint and might have been otherwise altered by someone in the past since the threaded side is buggered up. Any leads on parts would be helpful, preferably on the USA side but I've ordered my share of parts from the UK and Europe so used to that if need be. Or tips if I can simply wedge something like a spring washer between the rear of the retaining pin and the timing cover.
email (option): dgordon4@austin.rr.com
Hi David..Buy a NOS or good used oil pump drive spindle to avoid the incorrectly machined ones currently being offered by many sellers (these are of Indian origin) The washer that fits in after the shaft retaining peg is not a standard washer size so you will have to file down the OD of a 1/4" washer, turn something up on a lathe or investigate the possibilities of the spring washer as you mentioned...that should work fine if you can locate one of the appropriate dimensions...Ian
email (option): ian@wright52.plus.com
The oil pump spindle was OK. It was just the spindle retaining pin that was messed up. Figure someone before me had learned that the extraction thread size isn't the same as a timing screw (as indicated in some wartime manuals) and they buggered it up pulling it out. I myself used an EZ-Out bit because there were no apparent threads on it anymore. Since it had worked before, I likely lost any washer that had previously been inserted as a spacer. Probably stuck to the old gasket and sealant.
To test, I used a pair of 3/8" diameter flat washers which filled up the needed space perfectly. Used grease to hold them together and to keep them in position until I got the timing cover back on. Pump and sump cover installation only took a few minutes now that I've gotten quite proficient at it. Another task mastered that I unfortunately can't use in day to day life....
Started the machine up and within 30 seconds I had oil flowing back to the tank even though I'd not primed the pump or either oil line so guess the problem is resolved.
Many thanks to everyone on the forum that responded on the message thread or via direct eMail. I'll post a photo of the bike in a separate thread once I get it off the stand and we have a sunny day this weekend.
email (option): dgordon4@austin.rr.com
Good news David. It seems these drive spindle retaining pegs are in different lengths. Some require a support washer and some don't. I found a perfect size fibre washer for mine. And yes the books are wrong! I've seen a few buggered pegs where people have tried to fit a Whitworth case screw when in fact the thread is BSF. Ron
email (option): ronpier@talk21.com
Hi David..as Ron says there are small variations in the crankcases/pegs that sometimes mean you don't need the washer..However, the difference is quite small and no more than one washer should be needed. There are shaft retaining pegs from other engines that are substantially shorter than the M Series ones and although they can be 'packed out' they are not the correct part..(if you are concerned about that sort of thing)....Ian
email (option): ian@wright52.plus.com
I used a brass drift and made sure the retainer was set into the groove of the spindle prior to installing the oil pump that last time. This allowed me to press on it from underneath to verify it really was held before bolting everything up again. Not sure if it was original and messed up on the threaded side which shortened it over time, or if it is from another model bike. Either way, it fits the diameter of the hole and the notch on the spindle so I'll live with it being shimmed for size.
Need to make a note in my own manual similar to the Magneto removal where it says to note any shims as they will need to be replaced. Then I won't forget the washers if they come away with the timing cover next inspection.
email (option): dgordon4@austin.rr.com