Help! I have a 2000 Vulcan that is leaking from the lower oil drain bolt. I tried to slightly tighten that bolt only to realize the bolt seems stripped. When I did my last oil change I did find semi circular pieces of metal lodged against the screen/strainer. I now suspect that those pieces of metal were probably threads from the aluminum case where the bolt installs.

Am I totally screwed or is there a fix for this issue? I know with a stripped oil pan on a car, they sell a slightly oversized oil drain bolt that sort of self taps new threads when installed. Does anyone know the exact size and thread pitch for the oem bolt?

Any ideas or known fixes are appreciated.

It is probably fixable. But what do you mean by "lower oil drain bolt"? There is only one oil drain plug, on the lower left side of the engine near the sight glass. There is a wire mesh screen, washer, and spring behind it. If you are talking about the bolt on the bottom of the engine, it is not intended as an oil drain. If that is the one you are talking about, check to see if there are any internal threads left. If there are, you can use a rubber expansion plug. I have a 1964 Ford with stripped threads in the oil pan drain. I have been using a rubber expansion plug in it for years with no problems. I replace it every 2 oil changes. It can also be permanently repaired with a HeliCoil or TimeSert, but those are a bit more difficult.

It's an oil drain.

Don't use a rubber plug, you don't want 4qts of oil on your back tire at any speed. I would get an oversize self-tapping drain plug.

If it is the bolt on the bottom of the engine, neither the owners manual or service manual says anything about using it as an oil drain. But yes, if you remove it, the oil will drain out. If you want a permanent fix, I would take it to a shop and have them either retap the threads for a larger bolt (remember it has to be a flanged bolt) or install a threaded insert to fit the stock bolt. I never trusted self tapping bolts in a place like that. They can cause even more damage. IF you can find one, don't try and screw it in all the way all at once. Screw it in a little, remove it, and then screw it in a little more and remove it again. It will take several times to get it all the way in. Make sure you don't get any more thread shavings in the engine.

Yes, the repair manual designates the cap with the oil pump screen as the drain, but the other bolt is still a drain. What else could it be? Side note: You'll always get more oil drained by using that side cap. Don't over-torque the cap, many get destroyed when they get stuck.

A self-tapping bolt, is essentially a tap, with a hex head on it. The only way it would damage anything is over tightening it. Oil plugs, the cap with the oil pump screen, and bleeder valves, never need to be torqued tight, just snugged is enough. Even if the self-tapper strips out, a Time-Sert, or helicoil can still be done. Tapping threads for a larger bolt, is the same as using a self-tapper.

I've seen many rubber expansion plugs just pop out, with oil and coolant, and always at the worst time. I oiled a mile long stretch of highway once. Company mechs used a rubber expansion plug on a truck that holds 3 or 4 gallons of oil. Oil covered the lane I was in.

You can do a Time-Sert, or helicoil at home if you're mechanically inclined.

You can make your own self-tapper with a bolt and a hacksaw. But they're cheap to buy, and there are some with their own drain plug. A self-tap bushing gets threaded into the hole (loctite would be good), then a drain plug threads into the bushing. I've never had any trouble with self-tap plugs.

Self-tapper


Self-tapper bushing and plug



Time-sert

Sorry, but I have to add...

Start the self-tapper and get a couple of turns on it, when it gets harder to turn, back off 1/4 to 1/2 turn, proceed. Add a couple more turns, back off 1/4-1/2, just until you feel it free up. Repeat until snug. Remove the plug and clean any debris from it. This is the same way you're supposed use a tap.

If you remove the plug before it's fully tapped, there's more risk of botching the job. You need one continuous spiral of threads.

Thanks for the help and ideas. Yes I'm talking about the bolt under the engine, not the left side oil drain with screen.
I'll make a stop at some auto parts stores today and see what I can fine as a self tapper.

Can anyone verify the oem size of the bolt? I think it may be M12x1.50. If I use a self tapper, do I go "oversized"? If so what size? read on another site to look at using a 1/2"-20 self tapper.

According to this, the stock bolt is 12mm (diameter) x 15mm (long). https://www.kawasakipartshouse.com/o...il-drain-12x15

But you can use SAE threads since you're cutting new threads. I would take the old bolt with me and match up to the next oversize. You can't jump too much in size though.