hole in crank case - small oil leak '81 GS450

[wormseatdirt]

I just bought an 1981 GS450E as my first motorcycle, put 1500 miles on it and began to notice an oil leak (it may have been leaking the whole time, since I've had to add about 1.1 Q of oil to keep it topped up). Upon further investigation (about 2 months later) I found a quarter-sized hole in an upper part of the lower crankcase that made my heart drop.

The guy I got it from said a newly installed chain had broken a few weeks previous to my purchasing it, and had damaged the clutch push-rod (which he fixed), but nothing else he had noticed, which I still believe. It ran fine, and has given me 0 problems since then.

So this hole, while gaping, doesn't seem to be life-threatening, but I would like to fix it so no long term damage is caused to an otherwise beautiful bike (I got it with only 6500 mi on it!).
Does it look weld-able? Or do I need to spend the next several months scouring ebay for the lower section of the crank case and/or engine?

[Easy Rider]

Originally Posted by wormseatdirt

Does it look weld-able? Or do I need to spend the next several months scouring ebay for the lower section of the crank case and/or engine?

My guess: No. I think any attempt at a "fix" would be a frustrating waste of time.

I know that Ebay and this new computer technology is great stuff but.........

Look for a salvage yard in your area. Even if they don't handle wrecked bikes, they can probably put you in touch with a yard that does. Might be able to get what you need MUCH faster that way.

Now, about taking apart the engine and putting it back together correctly: That may be a bigger problem than you think, if you've never done one before.

Soooo.....you might want to find out how much the labor will cost you to fix it up right (which is likely to be more than the part, if you can find it) BEFORE you shell out any $$$ for parts.

I know it's painful but your best course might be to sell it and start over.

And I just gotta say it: SOME of that oil HAD to be dripping around the bottom of the bike when you first looked at it. How come you didn't see it ??
Might want to look closer next time ??!!

[artistic_gore]

Yes it can be tig welded. It is pretty common with dirt bikes, I have a welded case on my 250 right now. I guess the only thing is you have to verify that that is the only damage. I would pull the chain cover and side cover and probably the chain and sprocket as well to inspect for damage. From the look of it you could probably get away with just pulling the engine and removing the side cover from it and have it fixed without having to split the cases at all.

I have to say though that it would probably be alot easier for the welder if you had the piece though someone with enough experience to do that kind of work can build up the metal and grind it back to look acceptable.

[pinky44]

I would suggest giving it a good clean down with the side cover off and inspecting for hair line cracks or leaking seals as the piece that is missing does not look from the pics to be right into the case if it was you would have no oil in the casings.

On the older GS,s the output shaft seal does leak after a while ( might take a few years ) so does the seal on the clutch push rod and the gear change shaft so the oil might be comming from one of these sources and not from the damage on the case. So as i said above give it a good clean so there are no traces of oil, dirt, ect and go from there.

And yes it could be welded by useing a tig welder you would just need to find somebody to do it. But they might just want the lower crank case not the whole engine.

[Aussie Steve]

From your pics I would suggest the piece missing is not the actual oil leak point. The case appears at that point to be just a mating surface for the outer cover that hides the chain and gearbox sprocket.

It may be that the chain break that went on to break the clutch push rod caused damage to the seal the rod runs in and it is at this point that oil is weeping. You do not state over what period the 1.1 Q of oil is needed so either the leak is small or huge.

You can get the case TIG welded like everyone says but the metal has to be chemically clean otherwise the weld will not take. Obviously the case needs to be clear of oil which means you either take it off or hope you can clean it sufficiently for it to be welded.

As for replacing it you would have to pull the whole motor apart to fit a new case which opens a whole new can of worms such a bearing line up, slight variations of case size and line up etc....I don't care what the Japs say about their motors being machined to fine tolerances they are prone to the discrepancies of missalignment just like any other.

Before running off and getting welding done or putting orders in for parts check where the oil is actually coming from. You may find it is just a seal that needs replacing...worst scenario is you will find a crack in the case where it really matters.

If it is this then try the following. Drain the oil. Thoroughly clean the area around the crack. Using a rough file create a "key" surface. Mix up some two part epoxy resin glue. Apply a generous coating and stick some cooking foil folded several times over the crack. Allow to harden and then coat the whole thing over with some more of the glue.......believe me it works and lasts a good few years too!

I just took another look at your pics and wondered what the bolt head shown is...it isn't your drain plug is it? If so then all of the above is moot.... the break will probably have cracked that hole where the bolt is and will be difficult to fix with any degree of success. Just took yet another look.... that isn't a separate sump is it? If so then all you have to do is remove it and either fit a new/old one or get it welded as suggested.......Hope it is!!

Good luck

[wormseatdirt]

thanks for all the advice and help!

i really hope the oil leak is from a more minor thing like a gasket, which seems more likely since there really didn't seem to be a leak, or much of one, when I first got it.

I plan on investigating more tomorrow, wiping it down and removing the side cover, as I am still having trouble (even with the service manual) figuring out where in the crankcase/cover/etc the hole actually is.

[wormseatdirt]

here's what i found under the cover.

I'm so relieved to see the hole is outside the actual case, not the case itself!!

two potential points where oil seemed to be leaking from was the shifter bearing, and the other is the lower left hand bolt hole, which had clear motoroil inside of it, as well as the bolt itself when I removed it. So could this be where a hairline crack is lurking??

I still want to stop the leak, but do you think this is managable now?

[wormseatdirt]

so i'm sorry for the play-by-play method of delivery, but I think the problem is solved.

i ran the bike for ~5 min to check things out and oil was nearly pouring out of the gearshift rod bearing. Success! What a relief! All it needed was further investigation....

So now i just need to replace the seal, right? i just don't know how hard it would be to replace it, or how much the shop would charge to do so...

thanks for all the advice!

[artistic_gore]

Personally, I'd get a new seal. Drill a small hole in the old one, grab it out with a pick and drive the new one in. I could be wrong.

[Aussie Steve]

+1 for Artistic gore...that is exactly how you get the old one out and the new one in. A socket of the right size is perfect for drifting the new seal in.....make sure you keep it even as it goes in. As for the old one another trick is to carefully hammer a small screwdriver to one side of the outer ridge. This usually tilts the seal and allows you to grab it with some long nose pliers. Be careful not to damage the seal housing in any way. Size should be on the rubber seal outer face.


Good luck