Common major oil leak fix

After digging around on my XT, I discovered a stripped bolt hole in the clutch case, where the oil filter lives. It's a very common issue on this motorcycle.

The drain bolt

The oil filter has a separate cap, so it can be cleaned and changed without taking off the full cover. To drain the oil out of the filter area, there's a special bolt hole that doubles as a drain. When the maintenance is done, this bolt comes out first so the oil can drain out of the filter area.

This is an aluminum case, and it's very easy to strip out.

Aluminum is much softer than a steel bolt. A bolt that comes out and goes back in at every filter change, tightened a little too hard, wears the threads in the case away.

"It doesn't leak"

I'd asked the seller specifically whether it leaked oil, and he said no. But when I was checking the oil filter, it was obvious the bolt was stripped.

The oil doesn't sit in this area, so it doesn't leak unless it's running. And the bolt that was in there wasn't the stock bolt — in hindsight, a clue that the issue was already known.

The bolt in there wasn't the stock bolt — in hindsight, a clue the issue was already known.

A new cover, or a repair

I looked up a new case cover, but they're expensive — many of them are already damaged — and they're mostly in Europe, since this was a more popular bike there.

I figured if I was going to order an expensive case anyway, I might as well try to repair this one first.

The Helicoil

Since this is a common issue, there are good write-ups on it online. I read a few, and went with a Helicoil as the method to try.

It's stressful, but I was able to get the job done right. I used red thread lock, which is permanent.

Plugging the drain

I assumed the Helicoil would block the drain hole the same way the bolt does in the original design. It does not. A Helicoil is more like a spring than a bolt — its threads aren't attached to each other, so oil can seep through.

So the second part of this repair is to plug the drain hole in the case with an oil-rated gasket maker, so the oil can't drain out that way. It can only enter and exit the way it does during operation.

The fix doesn't affect lubrication, but it does make changing the oil filter a bit messier. With no drain hole for the filter area, all the oil in there is still in there when you take the cover off, and it comes out the cover hole. That said, a bit of oil always came out that way.

A small price to pay for a bike with no leaks.

A bit messier at oil changes. A small price to pay for a bike with no leaks.

A crush washer

The final piece is a crush washer on the new bolt, since this bolt now plugs the hole from both the top and the bottom.

A crush washer is a soft metal washer that flattens as the bolt is tightened, filling the gaps so oil can't get past.

So far so good. And if it comes to it, I can always buy a new cover from Latvia.