Hi,
I have a 1954 Plunger BSA B31.
I had to take timing case cover off to have work done on magneto. This ended up taking a few months, so cover was off bike for quite a while.
When I put everything together and went for a test run, I noticed that after a few miles, oil was 'pulsing' out from the bottom right hand side of timing case. When engine stopped the oil leak pulsing stopped. There seemed to be a build-up of pressure in the timing case. Thus, the pulsing oil leak. Not just a slow drip.
I stripped it down again but noticed a few things and have a few queries. I have now taken cover off three times, but each test ride gives the same problem.
1. Oil was returning to oil tank and circulating to head.
2. I noticed that oil quill dropped out very easily and when put back in rotates very easily in its correct position, when I re-seated quill each time I ensured that hole in base of quill was aligned with hole in the place where you seat the quill but each time, I take it off, it has rotated, is this normal? Am I missing a circlip or seal for quill?
3. Would the breather be blocked causing a build up of pressure, although I did shoot compressed air down the hole of the copper crimped tubing and it exhausted to the outside ok, when I reversed this procedure, air was prevented form going back up copper tube. Can I assume breather is working correctly? Should hole in copper breather tube be facing the cover casing (pointing away from bike, see photos)
4. Would the rubber grommets/seals in the timing cover be damaged/dried out causing excessive oil to enter timing casing and thus a build-up of pressure?
5. I checked oil level in primary casing ......all fine.
6. I checked sump, no excessive oil but filter needed cleaning.
7. Checked spring and ball bearing of the non-return...all fine.
8. I have cleaned faces of timing case etc and used a new gasket each time I took cover off and used a smear of Wellseal to help seal the gasket.
Thanks in advance for any advice
I presume that the gasket is new of good quality and was lightly greased.
Threads of screws and case all clean? The oil pressure release valve cover washer is new and that the ball/spring are in the correct order and ball is seating. The quill will always get leak by and the rubbers on the cams need to be intact but unlikely a big issue. Oil is probably being blown out of the oil hole in the bottom of the cover bypassing the gasket.
The quill should be a press fit into the timing cover i.e. shouldn't be loose!!
Quote from: neil1964 on 23 Jun, 2025, 07:49 I presume that the gasket is new of good quality and was lightly greased.
Threads of screws and case all clean? The oil pressure release valve cover washer is new and that the ball/spring are in the correct order and ball is seating. The quill will always get leak by and the rubbers on the cams need to be intact but unlikely a big issue. Oil is probably being blown out of the oil hole in the bottom of the cover bypassing the gasket.
Hi yes, all new gaskets which I buy from Dragonfly (seem good quality) and I also use Well seal. I bought a new set of casing screws to see if it would help, oil pressure release valve cover washer is new. I will buy new rubbers for cams. Ball bearing is seated properly and both spring and ball bearing are new
What also concerns me is the oil quill when seated is very loose and seems to be turning when in situ therefore not lining up with the whole for the big end feed. I align hole from quill and casing cover, but when I take cover off again, they are always misaligned.
Also, it's not just a drip leak between the cover and gasket it is pumping out but stops when engine is stopped.
I have ordered new quill and Loctite 648 which is a retaining compound which will hopefully stop quill from rotating.
Thanks Brian
Quote from: Ian C on 23 Jun, 2025, 08:35 The quill should be a press fit into the timing cover i.e. shouldn't be loose!!
Hi
I have ordered new quill and Loctite 648 which is a retaining compound which will hopefully stop quill from rotating.
Thanks
Brian
Have you checked there is not a build up of old sealant in the bottom of the casing screw holes. I use a woodscrew etc . It is supprising how much gets compacted in the bottom and reduces the clamping pressure.
Quote from: cdsdorset2 on 23 Jun, 2025, 09:34 Have you checked there is not a build up of old sealant in the bottom of the casing screw holes. I use a woodscrew etc . It is supprising how much gets compacted in the bottom and reduces the clamping pressure.
Yes did that and picked everything out, the new casing screw set are slightly longer than casing screws on the cover, they fit perfectly and definitely get a better clamp or grip. I measured the length of screw holes and the new screws are not too long and fit ok.
Cheers
Brian
Quote from: cdsdorset2 on 23 Jun, 2025, 09:34 Have you checked there is not a build up of old sealant in the bottom of the casing screw holes. I use a woodscrew etc . It is supprising how much gets compacted in the bottom and reduces the clamping pressure.
I use a drill bit rotated by hand. Amazing how much rubbish comes out.
Quote from: V500 on 23 Jun, 2025, 10:22 Quote from: cdsdorset2 on 23 Jun, 2025, 09:34 Have you checked there is not a build up of old sealant in the bottom of the casing screw holes. I use a woodscrew etc . It is supprising how much gets compacted in the bottom and reduces the clamping pressure.
I use a drill bit rotated by hand. Amazing how much rubbish comes out.
Just did what you advised, amazing! loads of rubbish came out.....but don't think thats the problem.
Cheers
Brian
Although far from expert I've never seen a loose quill, and I guess from your description it is rotating and blocking the exit via quill to big end so all of the oil feed pressure is going to the oil way between timing cover and crankcase.
I've not used 648 (I use 243 blue as stud lock and 641 bearing fit) but I understand it is the green one that after 24hours cure is said to be very strong bond (assuming thorough cleaning prior) so correct alignment first time!!
Good luck and let us know how you get on.
Quote from: neil1964 on 23 Jun, 2025, 12:34 Although far from expert I've never seen a loose quill, and I guess from your description it is rotating and blocking the exit via quill to big end so all of the oil feed pressure is going to the oil way between timing cover and crankcase.
I've not used 648 (I use 243 blue as stud lock and 641 bearing fit) but I understand it is the green one that after 24hours cure is said to be very strong bond (assuming thorough cleaning prior) so correct alignment first time!!
Good luck and let us know how you get on.
Have ordered the bits and pieces so hopefully get job done this week and next, will let you know how it went.
Thanks for your advice
Brian
Quote from: neil1964 on 23 Jun, 2025, 12:34 Although far from expert I've never seen a loose quill, and I guess from your description it is rotating and blocking the exit via quill to big end so all of the oil feed pressure is going to the oil way between timing cover and crankcase.
There isn't oil pressure on the quill but there is some on the cams due to the seals between timing cover and cam shafts. Also the quill has an undercut as shown on Brians picture in the position of the oil feed hole, so can be fixed in any 360° postion and oil will still get to the big end. My comment was that if the quill is loose in the timing cover more oil would 'possibly' be escaping into the timing chest than designed.
In view of the quill being loose, I'd investigate why this has occurred. Is it a case of there not being enough concentric clearance between quill and crank?
To Brian, Have you tried placing the quill into the end of the crank and turning it?
Quote from: Ian C on 23 Jun, 2025, 16:19 Quote from: neil1964 on 23 Jun, 2025, 12:34 Although far from expert I've never seen a loose quill, and I guess from your description it is rotating and blocking the exit via quill to big end so all of the oil feed pressure is going to the oil way between timing cover and crankcase.
There isn't oil pressure on the quill but there is some on the cams due to the seals between timing cover and cam shafts. Also the quill has an undercut as shown on Brians picture in the position of the oil feed hole, so can be fixed in any 360° postion and oil will still get to the big end. My comment was that if the quill is loose in the timing cover more oil would 'possibly' be escaping into the timing chest than designed.
In view of the quill being loose, I'd investigate why this has occurred. Is it a case of there not being enough concentric clearance between quill and crank?
To Brian, Have you tried placing the quill into the end of the crank and turning it?
Hi Ian,
To Brian, Have you tried placing the quill into the end of the crank and turning it?
Do you mean turn the kick start over?
The quill turns ok by hand when inserted.
cheers
Brian
Thanks for confirming Brian. :)
Quote from: Ian C link=msg=115801There isn't oil pressure on the quill but there is some on the cams due to the seals between timing cover and cam shafts. Also the quill has an undercut as shown on Brians picture in the position of the oil feed hole, so can be fixed in any 360° postion and oil will still get to the big end. My comment was that if the quill is loose in the timing cover more oil would 'possibly' be escaping into the timing chest than designed.
In view of the quill being loose, I'd investigate why this has occurred. Is it a case of there not being enough concentric clearance between quill and crank?
To Brian, Have you tried placing the quill into the end of the crank and turning it?
How does oil get to the big end?
What happens if the quill is in too far and occludes the oil ways?
If the timing cover seals are too far in on a DBD you lose big end feed.
Quote from: Ian C on 23 Jun, 2025, 16:19 In view of the quill being loose, I'd investigate why this has occurred. Is it a case of there not being enough concentric clearance between quill and crank?
To Brian, Have you tried placing the quill into the end of the crank and turning it?
Might be an idea to check the truth of the crankshaft as this could a reason why the quill has come loose.
Quote from: Derek996 on 24 Jun, 2025, 11:17 Quote from: Ian C on 23 Jun, 2025, 16:19 In view of the quill being loose, I'd investigate why this has occurred. Is it a case of there not being enough concentric clearance between quill and crank?
To Brian, Have you tried placing the quill into the end of the crank and turning it?
Might be an idea to check the truth of the crankshaft as this could a reason why the quill has come loose.
To be honest I have no idea to check the truth of the crankshaft?
Thanks
Brian
A quick method to get an idea is to use one of the timing cover screw holes to attach a pointer. Line it up so it is a fraction of a millimetre from touching the crank at the side of the tip where the quill fits. When you rotate the crank and eyeball the gap the distance should remain the same, if not there is a bend on the shaft.
To get a more accurate measure you would need to do the same with a dial guage with the tip of the guage just touching the shaft. Any run out will show by the variation on the needle. Maybe up to about .002" to .004" is probably acceptable.
Quote from: Derek996 on 24 Jun, 2025, 16:16 A quick method to get an idea is to use one of the timing cover screw holes to attach a pointer. Line it up so it is a fraction of a millimetre from touching the crank at the side of the tip where the quill fits. When you rotate the crank and eyeball the gap the distance should remain the same, if not there is a bend on the shaft.
To get a more accurate measure you would need to do the same with a dial guage with the tip of the guage just touching the shaft. Any run out will show by the variation on the needle. Maybe up to about .002" to .004" is probably acceptable.
Great and thanks
Brian
Intrigued to know if this has been resolved?
Quote from: neil1964 on 30 Jun, 2025, 09:46 Intrigued to know if this has been resolved?
Got the parts on Wednesday evening then was away a few days motorcycling, only back last night, I aim to get job done tomorrow and will let you know.
cheers
Brian
Quote from: briancairns on 30 Jun, 2025, 12:17 Quote from: neil1964 on 30 Jun, 2025, 09:46 Intrigued to know if this has been resolved?
Got the parts on Wednesday evening then was away a few days motorcycling, only back last night, I aim to get job done tomorrow and will let you know.
cheers
Brian
Hi
I am afraid after test run oil is still leaking from bottom right hand corner of timing case cover and now also a bit from the breather:
work done:
Cleaned breather valve
cleaned casing cover and screw holes thoroughly
New casing cover bolts
New big end oil feedquill ( which still wasn't overly tight) and used locktite 648 to lock quill in appropriate position
new camshaft oil seals
Checked trueness of crankshaft ( as best I could)
Tested oil flow back to oil tank and also feeding the head
New gasket using WellSeal jointing compound.
I only went 2 miles and stopped to check but oil started to drip out of timing case and a few drops from breather.
Think I will now seal bottom right hand corner of timing cover and gasket with CT1 sealant or black instant gasket........all out of ideas
Thanks all
Brian
I presume that you know it is not wet sumping and the breather disc is moving freely?
Oil from the breather sounds like excess crankcase pressure being part of the issue?
Quote from: neil1964 on 05 Jul, 2025, 09:10 I presume that you know it is not wet sumping and the breather disc is moving freely?
Oil from the breather sounds like excess crankcase pressure being part of the issue?
Definitely not wet sumping as I also took sump plate off to clean filter all ok. Yes breather is moving freely after I cleaned it. I have no idea why there seems to be excess crankcase pressure. Bike was going fine until I took magneto off to get a bearing changed. Put it together, set timing, starts 1st kick every time . I ended putting granville clear sealant around gasket etc and will test ride again tomorrow but concerned that there definitely seems to be excess crankcase pressure.
Thanks
Brian
checking the breather with a air line is to powerful the breather works on low pressure, a airline need to be turned right down to do this, i tend to blow and suck, now if there is crankcase pressure there are only two small drain holes from the timing cover chamber to the main crank case were it scavenges , if pressure builds up in the timing cover chamber it will raise its oil level as it will not drain quick enough and come out the breather, this level can be raised for numerous reasons worn bores, guides air leaks quill leaking excessively, the issue is caused by the timing case filling up, you need to find out why, i find these engine run well till you disturb them and this happens, try a compression check for starters, these breathers are useless and take very little not to work so start there and move on
Quote from: paulm on 05 Jul, 2025, 12:37 checking the breather with a air line is to powerful the breather works on low pressure, a airline need to be turned right down to do this, i tend to blow and suck, now if there is crankcase pressure there are only two small drain holes from the timing cover chamber to the main crank case were it scavenges , if pressure builds up in the timing cover chamber it will raise its oil level as it will not drain quick enough and come out the breather, this level can be raised for numerous reasons worn bores, guides air leaks quill leaking excessively, the issue is caused by the timing case filling up, you need to find out why, i find these engine run well till you disturb them and this happens, try a compression check for starters, these breathers are useless and take very little not to work so start there and move on
I also took breather of the casing cleaned in petrol, disc flapping no problem, did the blow and suck thing, no problems. I replaced quill as one in bike was far to loose and spinning, the new quill although tighter , could still be spun by hand so used loctite 648 to fix in correct position ( this loctite is used to keep bearings in place etc). Will try compression test . I blew compressed air through all passages in timing case cover, no issues.The breather only blew out a very small amount of oil, the main leak was from bottom right hand side of cover.
cheers
Brian
Unless I have misunderstood your problem, you may be looking for a problem that doesn't exist.
Now that you have solved the quill problem, I would suggest you firstly carry out a Cylinder Leakage Test. You can find details on the Internet, although mostly USA.
Kits are available, but they are rather expensive, as you'll probably only use it once. I made up my own kit, but it ended up costing the same.
This will tell you if you have excessive crankcase pressure and more.
I had the same problem on a Vintage BSA, with sealant being pushed out of the joint by pressure (of which there will always be some). I tries all sorts of sealants, but having discovered the engine did not have excessive crankcase pressure, I used Loctite 518 and the problem was solved. I keep it in the freezer, disguised as a cucumber.
Do check the mating surfaces where it's leaking carefully with a straight edge. Perhaps you could loosely assemble the cover without gasket, and check the gap all the way round with a thin feeler gauge?
Quote from: Steve.S on 05 Jul, 2025, 18:04 Unless I have misunderstood your problem, you may be looking for a problem that doesn't exist.
Now that you have solved the quill problem, I would suggest you firstly carry out a Cylinder Leakage Test. You can find details on the Internet, although mostly USA.
Kits are available, but they are rather expensive, as you'll probably only use it once. I made up my own kit, but it ended up costing the same.
This will tell you if you have excessive crankcase pressure and more.
I had the same problem on a Vintage BSA, with sealant being pushed out of the joint by pressure (of which there will always be some). I tries all sorts of sealants, but having discovered the engine did not have excessive crankcase pressure, I used Loctite 518 and the problem was solved. I keep it in the freezer, disguised as a cucumber.
Do check the mating surfaces where it's leaking carefully with a straight edge. Perhaps you could loosely assemble the cover without gasket, and check the gap all the way round with a thin feeler gauge?
Thanks for your advice, a friend has a cylinder leakage test kit ( I think!) so hopefully will be able to check soon. Tried the straight edge across mating services but didn't detect any troughs etc but will try the feeler gauge technique.
cheers
Brian
Bottom right hand side? are we talking were the pressure release valve is? maybe a photo would help not sure were you mean exactly, however there is or should be a hole in the gasket for the pressure release, is this covered up
Quote from: paulm on 06 Jul, 2025, 10:32 Bottom right hand side? are we talking were the pressure release valve is? maybe a photo would help not sure were you mean exactly, however there is or should be a hole in the gasket for the pressure release, is this covered up
My timing cover was cracked next to the non return valve, probably caused by the screw being over tightened. Is there any chance that this is the cause of the problem?
I fixed it with JB Weld, after undercutting the crack.
Quote from: paulm on 06 Jul, 2025, 10:32 Bottom right hand side? are we talking were the pressure release valve is? maybe a photo would help not sure were you mean exactly, however there is or should be a hole in the gasket for the pressure release, is this covered up
Hi, there is definitely a whole in gasket for non-return valve, it is the correct gasket and all holes are as they should be. I aslo replaced the ball bearing and spring.
I have 'scribbled' a red line on attached photo , where the oil leaks from, that is oil drips between cover and body of timing case However only leaks when engine is running.
Thanks
Brian
Quote from: Rog1 on 06 Jul, 2025, 17:08 Quote from: paulm on 06 Jul, 2025, 10:32 Bottom right hand side? are we talking were the pressure release valve is? maybe a photo would help not sure were you mean exactly, however there is or should be a hole in the gasket for the pressure release, is this covered up
My timing cover was cracked next to the non return valve, probably caused by the screw being over tightened. Is there any chance that this is the cause of the problem?
I fixed it with JB Weld, after undercutting the crack.
Definitely no cracks in casing.
Thanks
Brian
sound quite possible
Quote from: Steve.S on 05 Jul, 2025, 18:04 Unless I have misunderstood your problem, you may be looking for a problem that doesn't exist.
Now that you have solved the quill problem, I would suggest you firstly carry out a Cylinder Leakage Test. You can find details on the Internet, although mostly USA.
Kits are available, but they are rather expensive, as you'll probably only use it once. I made up my own kit, but it ended up costing the same.
This will tell you if you have excessive crankcase pressure and more.
I had the same problem on a Vintage BSA, with sealant being pushed out of the joint by pressure (of which there will always be some). I tries all sorts of sealants, but having discovered the engine did not have excessive crankcase pressure, I used Loctite 518 and the problem was solved. I keep it in the freezer, disguised as a cucumber.
Do check the mating surfaces where it's leaking carefully with a straight edge. Perhaps you could loosely assemble the cover without gasket, and check the gap all the way round with a thin feeler gauge?
Did a compression test and got 155 psi...should I still do a leakage test? still waiting on my friend to lend me his kit.
cheers
Brian
Well, Brian, 150 lbf/sq.in. is good and would tend to indicate that you may not have too much pressure passing by the rings. It all depends on how concerned you are about excessive crankcase pressure. 'IF' your breather is blocked, then the pulsing will be more pronounced, but even if it is clear, I imagine there would be some normal pulsing as the piston descends.
My feeling is that assuming the mating surfaces are 100% and with new thickish gasket, the crankcase pressure would have to be considerable to force a leak, and I don't think it is. Are you certain it's coming from the joint?
If so, I would try the Loctite product (leave it overnight before you start the engine). I wonder if you might fit the screws without the case, to ensure they're going in far enough to clamp the case? Someone might have fitted longer screws?
If you're convinced there's too much pressure, then try the Cylinder Leakage Test.
However, be warned that when you apply air pressure to the cylinder with the piston at TDC and both valves closed, as you further open the regulator, it will become increasingly difficult to hold the engine at TDC (Putting the bike in gear with the brake on certainly won't work.) If you get up to a high pressure and your jamming method lets go, it could be catastrophic.
I've just had another thought. Is the screw hole adjacent to the leak in communication with the timing chest? If so, you may want to fit that screw with a sealant such as Hylotite Red, with, maybe a fibre washer.
Quote from: Steve.S on 09 Jul, 2025, 03:35 I've just had another thought. Is the screw hole adjacent to the leak in communication with the timing chest? If so, you may want to fit that screw with a sealant such as Hylotite Red, with, maybe a fibre washer.
I used Granville Clear Gasket Sealant around the area which leaks, so will do a test run later. If leaks again I will look at fitting a fibre washer etc to screw adjacent to leak. Don't think I will do cylinder compression leakage test. Also I think I will blow compressed air up the oil tank breather tube to ensure there is no blockage there.
cheers
Brian
Quote from: briancairns on 09 Jul, 2025, 03:45 Quote from: Steve.S on 09 Jul, 2025, 03:35 I've just had another thought. Is the screw hole adjacent to the leak in communication with the timing chest? If so, you may want to fit that screw with a sealant such as Hylotite Red, with, maybe a fibre washer.
I used Granville Clear Gasket Sealant around the area which leaks, so will do a test run later. If leaks again I will look at fitting a fibre washer etc to screw adjacent to leak. Don't think I will do cylinder compression leakage test. Also I think I will blow compressed air up the oil tank breather tube to ensure there is no blockage there.
cheers
Brian
ok, I blew compressed air up the oil tank breather, heard a pop, air flowing freely. Took bike out for 10 mile test run, slight oil weep from timing case and the odd spit of oil from timing case breather. I think that's the best I'm going to get.
thanks all for the marvellous advice.
Brian
Just a thought. Exactly where the leak is showing there is an alloy plug in the timing cover sealing a drilling for the oil gallery to the crank feed. There is a (very) small possibility that it is leaking from the plug.
Quote from: Derek996 on 09 Jul, 2025, 13:49 Just a thought. Exactly where the leak is showing there is an alloy plug in the timing cover sealing a drilling for the oil gallery to the crank feed. There is a (very) small possibility that it is leaking from the plug.
Is the alloy plug in the area marked with a red circle ?
No, it's on the outside of the casing directly below the the oilway that runs from the small hole in the cover to the crank feed quill.
Not sure my casing has what your are referring to?
Cheers
Brian
I believe Derek is refering to the alloy plug circled in red which was fitted after BSA machined the oilway to the quill.
Quote from: Ian C on 09 Jul, 2025, 17:36 I believe Derek is refering to the alloy plug circled in red which was fitted after BSA machined the oilway to the quill.
No , My casing definitely does not have that...1954 BSA plunger
Quote from: briancairns on 09 Jul, 2025, 17:48 Quote from: Ian C on 09 Jul, 2025, 17:36 I believe Derek is refering to the alloy plug circled in red which was fitted after BSA machined the oilway to the quill.
No , My casing definitely does not have that...1954 BSA plunger
They all have it Brian, even my 1948 B32. It's a necessary part of the manufacturing process but if your's is more or less invisible it's probably not the source of the leak.
Quote from: Derek996 on 09 Jul, 2025, 19:08 Quote from: briancairns on 09 Jul, 2025, 17:48 Quote from: Ian C on 09 Jul, 2025, 17:36 I believe Derek is refering to the alloy plug circled in red which was fitted after BSA machined the oilway to the quill.
No , My casing definitely does not have that...1954 BSA plunger
They all have it Brian, even my 1948 B32. It's a necessary part of the manufacturing process but if your's is more or less invisible it's probably not the source of the leak.
Apologies, ok thanks.
cheers
Brian
Brian, Sounds like you have cured the problem. Well done. Perhaps the pop you heard was a dead rat being expelled from your pipe? Now get out there and give it a damned good thrashing, just to settle things in.
Quote from: Steve.S on 10 Jul, 2025, 17:09 Brian, Sounds like you have cured the problem. Well done. Perhaps the pop you heard was a dead rat being expelled from your pipe? Now get out there and give it a damned good thrashing, just to settle things in.
😂👍🤞 hopefully that will be it
thanks all
Brian