mcman56 Posted December 31, 2012 Report Share Posted December 31, 2012 Is there a recommended process to make a C15 not a big oil leaker? When running, my C15 leaks oil on to the bash plate and then to the ground so it is unclear where it is leaking from. I don't see any obvious leaks from gasket areas. After parked for a couple of days, it starts to leak which I believe is wet sumping. All check balls and springs were replaced but during the rebuild most everthing was corroded so the condition of the ball seats is unknown. There is a tube fitting on the head which I connected to the oil tank so there is no real breather...is this correct? The frame has a right side kick stand that would seem to make the leaks worse with all of the vents/ holes on the right side of a 1960 engine. Quote Link to comment Share on other sites More sharing options...
woody Posted December 31, 2012 Report Share Posted December 31, 2012 To stop mine from wet-sumping when parked up, I used to gently clamp (so as not to damage /crush the pipe) a pair of flat jawed mole grips onto the oil feed pipe from the tank to cut off the the oil feed. They'd stick out of the side of the bike so there was no way I could forget to remove them when starting the engine. This stopped the wet-sumping at least and therefore leaks when sitting in the garage. The leaks themselves could be anything from damaged gasket faces, wrong type sealant etc. If it spews out oil when running, a possible cause is pressure build up due to the venting system not working properly. Adding extra vents as is sometimes suggested doesn't cure this (I've been assured by a BSA specialist) so first thing to check is that it is venting properly from the vent in the bush on the crank (where the cam is) and through the airways in the casings on the clutch side. Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 31, 2012 Report Share Posted December 31, 2012 I'm guessing its engine oil ? Gearbox can leak from the seal behind the sprocket, kickstart shaft, or any of the covers, buts clear so should be easily identifiable. Primary can leak round the casing, seal behind clutch, but on mine oils red, so again easily identifiable. Side stand was moved to right to keep the clutch as dry as pos' so it wouldn't slip when starting. They all seam to wet sump, eventually. The ball valves and seats seam to be the problem, but on mine if I leave it on compression the pump position slows the oil so it takes a lot longer to fill the sump. As Woody said, the engine vents on the down stroke of the piston through the cam and into the casing below the timing cover / distributor, then out through a small pipe beside the clutch arm. Any oil that gets blown into the casing below the points, should return through the tiny hole in the otherwise empty casing. Which oil are you running it on ? The correct oil is heavier than the 20/50 that I use, but I buy it cheap and change it often. Rupert Ratio is a mine of information, if you haven't seen it yet. I have a vent from one of the rocker covers, and you can feel it breathing. I have a short length of clear pipe attached and terminated under tank. I assume you also have a breather on the oil tank ? Again on mine I had to reposition the outlet as on steep up hills the oil would come out. Mine is a modified tank/position. I change the gasket on the cover under the oil pump to a heavier home made one as I had a slight seap. Also check the two pipes going/coming from the oil pump arnt leaking. Quote Link to comment Share on other sites More sharing options...
big_red_bike Posted December 31, 2012 Report Share Posted December 31, 2012 Hi if the engine is leaking oil it has to be a joint not sealing .If the engine is wet sumping it will fill with oil from the tank but not leak out,you can tell upon start up as the engine will smoke until excess oil is returned to the tank.Also the pipe to the head check it is a breather pipe and not the rocker box oil feed pipe. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted December 31, 2012 Author Report Share Posted December 31, 2012 Are you saying that there should be a vent to air on the oil tank and another vent to air on the cylinder head? I have these two connected together so they are trying to vent to each other and not air. I suspect that this may be why it is leaking when running with internal pressure pushing oil out into the timing cover. If the engine speed gets really slow to an almost stalling speed, it makes this weird wheezing sound that I have not heard in an engine before. This is also my only Brit bike experience so could that be normal? It takes about a day and a half for oil to start leaking when parked. I suspect the sump fills up to a level where it can then leak out the vents in the timing cover. This has a right side kick stand that may make it worse. This is a 1960 and I don't think the timing cover is sealed as well as on the later models. I put a petcock on the oil line to stop the leak but worry that one day I'll forget to open before starting. I'm running 40 wt oil in weather from 60 to 90 F. Thanks for the input. Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 31, 2012 Report Share Posted December 31, 2012 (edited) I vent the oil tank to atmosphere, again just a transparent hose under the tank. Same for the breather on the rocker cover. If you have these connected together you may be pressurising the tank, easy to check if you open it after a ride. If you leave the engine on compression, the cam breather is closed I think, which slows the oil getting into the timing side case. If the case is well sealed the only exit is through the breather and that is high and would take a lot of oil. Again transparent hoses help identify any problems. (the cam breather is supposed to create a vacuum in the crankcase so a breather in the rocker cover probably cancels it out !) Your oil sounds really light for the ambient temp and also these engines can get pretty hot, especially if your timing is out ! I never leave my bikes sitting on their wheels, but that's probably just me. Edited December 31, 2012 by b40rt Quote Link to comment Share on other sites More sharing options...
woody Posted December 31, 2012 Report Share Posted December 31, 2012 Same for the breather on the rocker cover. I've been told you shouldn't do this by an ex BSA man as it interferes with the way the pressurising / depressurising of the engine works. The explanation he gave of how the system works and the affect of adding vents made sense, but I can't remember it.... His BSA doesn't have any of the 'recommended' extra vents from Rupert Ratio or anyone else and it has no oil leaks Quote Link to comment Share on other sites More sharing options...
b40rt Posted January 1, 2013 Report Share Posted January 1, 2013 Hi Woody The extra vents probably cancel the vacuum effect that the camshaft vent is supposed to create. I never have any leaks when the engine is running so hopefully it's ok. 1 Quote Link to comment Share on other sites More sharing options...
naichuff Posted January 1, 2013 Report Share Posted January 1, 2013 Both my B31 BSA and the two AJS's suffer wet sumping problems as they can stand for some time out of use over the winter Just removed over 1/2 a litre out of each last week 1 The BSA has a gear pump and as they wear allow oil to get past if standing for a long time The AJS's have plunger pumps still have the same problem but not as bad 2 The grade of oil is another factor I use straight 50 I tried 20/50 for cold running but made the wet sumping problem worse 3 These engines are road based and would be designed to run every day so wet sumping would not occur as much Quote Link to comment Share on other sites More sharing options...
mcman56 Posted January 1, 2013 Author Report Share Posted January 1, 2013 When new, what did BSA do with the vent on the oil tank and the one on the cylinder head? Was the cylinder head vent installed at the factory or could it be a modification? It is oddly close to where a valve lifter may be on other models. Quote Link to comment Share on other sites More sharing options...
woody Posted January 1, 2013 Report Share Posted January 1, 2013 There was no cylinder head vent from the factory, it's somebody's modification Quote Link to comment Share on other sites More sharing options...
whinger Posted January 21, 2013 Report Share Posted January 21, 2013 A up, when rebuilding my bsa engines I remove all dowels , pins, etc and with a sheet of glass large enough to take the cover check the faces for flatness. If a fine feeler gauge can be inserted between face and glass its a case of facing them using grinding paste on the glass using figure 8 pattern and patience. when a nice matt finish can be seen on all faces check with feeler gauges again, remember to remove all traces of grinding paste when satisfied Wet sumping,I think, is a pre condition of owning old brit bikes, fire them up every week this helps the oil from free draining, check all balls seats, springs on pressure relief valves . hope this is of use. good luck Quote Link to comment Share on other sites More sharing options...
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