Topic: Odd oil leak

[Fezzler]

Have oil leaking from lower left side of engine behind crankcase cover (1971 cb500 K0).  I assumed it was the gear shift rod seal, as I have had this issue on my '78 cb550.  I replaced the seal with a new one.  However, after cleaning well and observing, I think the oil is coming from the lower right crankcase bolt socket.  Is that possible?  Any thoughts welcomed.

[newday777]

Was that picture from after a ride or just setting unused? Time frame??

Oil will migrate. Clean the area well and dust it with baby powder to try and track it down better.

[Fezzler]

I've had the bike assembled about two years.  Sunday rider. No issues. Starts and runs great. I noticed after being parked (on center stand) for a about a week after a 30-40m ride.  Only other issue is I had noticed the oil light would come on recently at time when accelerating. But plenty of oil in engine.  Oil switch was new when I assembled the bike.

I have cleaned the area pretty well and I am confident it is coming from the lower right crankcase bolt socket.  I put the crankcase cover and shift pedal back on after replacing the seal and no leak after 5 hours.  We'll see.

[dave500]

theres a few spots on that left side where 500/550s can and do leak oil,check the oil pressure switch,they can leak from the crimped on plastic part,also use teflon tape on its tapered thread,also the oil pump to engine block o rings,the actual oil pump cover can leak its a very thin o ring,ive also had a leak from a gallery plug o ring on that left side but underneath,wind blew oil wicking down the shifter lever mimicking any leak from behind that left cover.

[Fezzler]

Thanks Dave.  I've been thinking about rebuilding the oil pump anyway.  I need to monitor and perhaps do the baby powder leak test.  But, as I said, I cleaned the area pretty well and I swear it is coming from inside that lower right crankcase bolt socket. I am often wrong and could be in this case.

[dave500]

that should be a blind hole,unless a too long bolt has been wound into it?

[bryanj]

The oil pump cover uses a 46 x 2 O ring that is not shown as a seperate part, Nurse Julie sells viton O ring kits for the oil pump.
As said that hole should not have any oil so unless the case is cracked it must be comming from elsewhere.

[Fezzler]

Thanks.  I'll compare the bolt length to OEM bolt.  The one now is from one of those replacement kits with Allen heads.

[bryanj]

Parts book will tell you what size it should be