Alternator oil leak

[Steel cowboy]

I replaced my alternator last week and now I've noticed an oil leak on the engine side of the alternator. When I pulled the old one out I noticed some scratches on the o-ring seat towards the bottom of the engine case. My question is I greased the surface were the o-ring rides before installing it. Should I be using some sort of sealer on the back side of the alternator housing when I reinstall it with the new o-ring?

[da prez]

  If all surfaces were clean and no burrs , you may have nicked it putting it back in. It would be best to pull it and check the current O-ring for a nick and note the location. Then check the surface for a scratch and clean if needed with superfine sand paper. If you use a sealer , make sure it is non-hardening.

                                     da prez

[MarkT]

When I installed my Compufire oversized alternator on Deerslayer I had to cut out a window in the O-ring seat to provide clearance to pass the alternator between the frame and the engine.  Even with an extra O-ring on the fwd face it still leaked oil.  That was a dozen years ago or so.  Maybe 6 years later I replaced it due to the oil messing up the brushes.  That time I used JB Weld to fill in the window, but also added a skin of oil so it wouldn't get fixed to the aluminum.  Still leaked. Now recently I replaced the alternator again because of the oil on the brushes.  This time I added liquid gasket sealer on the O-ring and also on the alternator where the o-ring is, and forward of it.  No more leaks and that has been several months now.

[Steel cowboy]

Thanks Mark, the o ring was cut probably during the install. I used the old one with some silicone rtv in the o ring grove and around the o ring. The old o ring is holding so I'm happy.
I still ordered a new o ring from action Honda which I'll hold on too. I'm taking the old alternator to get rebuilt as a spare.

[PA_1999Valk]

Buy a new o-ring.  Back out the alternator far enough to install the new o-ring.  I had the same problem with the o-ring on the alternator trying to maneuver it into the small opening.  My leak went away.

Carl