Re: Oil dripping from crank case vent after reconditioning the oil pump.
Did you drain the crankcase completely after you did the second repair?....It sounds as if you might not have....The strong return to the oiltank should only last as long as there is oil in the crankcase..When that has been cleared the only return you will get is a 'spit and bubble', as the larger capacity return gears will scavenge (empty) the crank case...
However, if there is too much oil in the crankcase from a previous weak return side on the pump it will be too much for the pump to immediately deal with and will be ejected from the breather until everything returns to the correct state...
If the bike is left standing and the engine 'wet sumps' as the oil drains into the engine you might get exactly the same result the next time you start it up unless you first drain the crankcase..
I don't like repeatedly taking out and replacing the drain plug as it can compromise the thread in the crank case..On all my engines I drill through the plug and tap it to 5mm to take a 5mm allen screw and fibre washer...That way you can just remove the screw to drain it and leave the plug in the cases.....Ian...
Re: Oil dripping from crank case vent after reconditioning the oil pump.
Yup,
Crankcase was drained, since I had the oil pump out that way in order to repair it. I always find it to be quite a nervous moment before the oil starts returning to the tank.
I have an aftermarket sump-plug of quite thick aluminum so no real worries about the threads.
Re: Oil dripping from crank case vent after reconditioning the oil pump.
Likely to be a bad flapper valve on the breather or even bad rings
I had a piston pin clip come loose and make a nice groove down the barrel
Up till 1/2 throttle ran like a gem
Over 1/2 throttle waterproofed everything behind and left a reaaly big pool of oil under the bike when parked .
Re: Oil dripping from crank case vent after reconditioning the oil pump.
Hm, interesting points gentlemen.
Thing is though, flap disc i just about new and the same goes for piston, rings and bore. I am kinda wondering if there is just plenty of oil in the "flap disc vicinity" from the first round of wetsumping...? I did rinse out the vent hose itself, perhaps I should take a look at the flap disc and what else. Maybe there isn't really a problem, just a case of airing it alla out...
However I did take the pump out (again) yesterday and found that the cogs on the return side measures a tiny bit smaller than some other cogs I had laying around. Going to put them in instead and adress the flap disc as well.
Re: Oil dripping from crank case vent after reconditioning the oil pump.
Hello again,
Today I finally found the problem:
The two holes in the pump body where the spindles/axels of the gears/cogs for the returnside sits hade become warn and loose to the point where they would let oil seep through. This then becomes an easier path for the oil to go rather than being pushed up all the way through the oiltank. The oil ended up going through to the feed side of the pump along with the new oil that is being fed from the tank. Voila wet sumping!
The problem only occurred when I fixed the feed side of the pump (se above) because before that the amount of oil going in was not enough for wet sumping.
Had a small bag of pump parts laying around and it seems I got it together ok. Did some driving round the block a few times and up and down the street and no dripping from the crank vent. Great success!
Re: Oil dripping from crank case vent after reconditioning the oil pump.
Ian Wright
Glad to hear you found the answer Simon...It's always interesting to hear of an unusual problem...Ian
Found the answer when I dipped the "nipple" at the bottom of the pump in some oil, worked the pump with a spanner and noticed that oil came pumping up through both holes and not just through the return-hole. Took some thinking to figure out why but when I did it was all quite obvious. At last!
