AJS & Matchless Owners Club

Yesterday I drained both the oil tank and the engine sump (quite a lot of oil in the engine) both plugs being refitted with new washers and the tank refilled to just below the scavenge pump return hole. Upon starting the engine there was a large discharge of oil to the garage floor coming from around the hole in the chassis for the sump plug although not the sump plug itself. Upon checking this morning the oil in the tank had fallen 40mm and there was 100ML of oil in the sump.

Have I got wet sumping that is causing a pressure build up in the sump when starting the engine and discharging through a vent that is not visible without removing the engine from the frame? I have both the bulbous side covers remove to aid detection but to no avail.

Any advice greatly appreciated.

Roger

After you drain the engine & oil tank + clean/replace the oil filter then refill the tank to about 1/2 inch below the return hole then starting & running the engine for a while the oil level in the tank will drop as the filter has taken some of the new oil as well as the sump and there is always a little oil left in the engine sump. I would think the excess oil you have on the floor will be what has been sitting in the cradle when dropping the oil just top the oil up take the bike for a run periodically checking the tank oil level during the run.

shifter

Shifter,
Thanks for the reply but I didn't touch the filter in this instance and its the old type that doesn't hold oil like modern day filters.
I would estimate the oil on the floor was a good half pint and I had cleaned the cradle as far as practical before starting.
Noted what you say about running the bike.
Rog

Did you also empty the chain case? Not sure what happens with G2s but may have over filled via crankshaft bearing during wet sumping?

Andy
Yes I did empty the chain case in fact both those bulbous alloy side castings are off the bike as I try to locate the source of this leak. Oil doesn't appear to be coming from the crankshaft bearing.

Did the bike drop any oil on the floor in the length of time you have had it before you did the oil change ?

shifter

Yes there was a slight leak but you could live with it.

Have you started - ran the bike and checked the oil level after topping it up after initial start up after the oil change to see if its still ok. Has it still got the same amount of oil loss that could be lived with or is it still dropping from the level and depositing a significant amount of oil?

shifter