Oil Filter Drain Bolt Watch It

My oil filter drain bolt was feeling gritty,so I was going to fill it up with aluminum foil rolled up in a ball.I just couldn't do it. Seem cheezy it would work,but cheezy. I sprayed some pb blaster in the drain hole to clean the threads out, it wasn't filling up,the pb blaster was going somewhere. I ended up taking the inner clutch case off,I had pb blaster sittting at the bottom of the clutch cover and transmission linkage. Once the drain bolt is removed you have a clear hole leading to the clutch area,once that bolt is removed you have a open end leading to the cases,so I do not suggest spraying contact cleaner or drilling a hole for a bearing to fill it up. You can do this,but do it with the inner clutch case off,or all that crap is going to mix with your oil. I ended up cutting a small piece of 6 gauge copper wire trimmed a little so it will fit in the hole,I wedged it in nice and tight.

I have to say,after I cleaned the threads out this is the smoothest the drain bolt went in.Before I had to use a socket AFTER ONLY 3 TURNS,now I can tighten it up all the way until it bottoms with my fingers. I definetly see these threads stripping in the future if you do not fill that hole. NICE CATCH grey.


Was the 6 gauge the same diameter? What did you have to trim?


Was the 6 gauge the same diameter? What did you have to trim?

I had 8 and 6 gauge copper wire the 8 was too small and the 6 was just a hair too big

I put the 6 gauge on my bench grinder and took a little off the end made it narrower very lightly and jammed it in the hole.

When I plugged the filter drain block off using a ball bearing...


... on my son's bike, I did it with the cover off. However, when I did mine, I did it with the cover in place.

For anyone who was unaware of the fact that the threaded hole here goes out the back and into the clutch case, it certainly does. That was how it was supposed to drain the filter well.

In any case, the chips from the repair here are easily controlled. If the threads need to be chased, the standard method of greasing the tap should be used. As for the drilling operation, first remove the header for access. Then clean the well and the cover flange and cover the oil feed hole in the well and the oil passage in the flange with tape. These are the larger of the two holes in the well, and the feed hole at the bottom of the cover flange, next to the offending threaded hole.

Insert a grease cotton swab into the threaded hole far enough to close off the drain passageway. After drilling the step into the drain hole, take a second greased swab and clean out the bore before removing the first swab.

Another approach to take would be to avoid the drilling part altogether and use a 5/32" ball. They can be a little more difficult to find, but not unreasonably hard. A ball that size could be driven directly into the existing hole without modifying it.

There have been several suggestions/attempts made to find a way to do this more easily, or without doing some part of it, usually the drilling. It was done as I wrote it up because that's the right way to do something like this, and it is exactly one of the ways manufacturers block the open ends of oil passages in all kinds of equipment.

The hole is drilled to a larger size part way down to create a step in the bore that prevents the ball from migrating down the bore should it ever be loosened. Remember that oil pressure will act to push it in farther. In this application, it isn't terribly critical that the ball not move down, but it's better if it doesn't. Driving a 5/32" ball in place without drilling and staking it down would probably work OK if you're just that afraid of using the drill.

The only proper alternatives to a ball plug here are a threaded plug (the fitting of which would create more chips than the drilling does by far), a steel cup plug and a straight aluminum bore plug. Anything else is apt to work loose, and mostly amounts to a jerry-rigged work around to avoid doing the job right. Frankly, it really isn't that hard.

i think ill have my buddy tig weld the hole, hes a fabricator and shouldnt have any problem doing it.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now