Crack in engine case

[zio]

I've got a crack in my engine case, right between the countershaft & ignition cover. It looks like it's been repaired before w/ JB, but I'm not sure. I've never noticed it before, as my countershaft seal was leaking & the whole area was always covered in grime. After replacing the countershaft seal & still noticing oily buildup, & did a thorough cleaning of the area & found that the repair is more extensive than I previously thought. After the last race, the whole case was caked in 1/4 inch thick mud. After the mud dried the next day, oil darkened the area where the repair had been.

Whenever I change the oil, it never appears to be low. But still, I'm concerned. I'm not positive that the leak is getting worse, but I wouldn't really know how to accurately accertain it. It could also be the gasket, too.

If it's the crack, is this something that can be repaired? If the leak is stopped (by more JB Weld), can I continue on with my "Out of sight, out of mind" way? If not, is the proper repair costly? Does it require splitting the cases? :whiner:

 

[biglou]

Here's what I would try: First, drain the oil out and clean the crack and surrounding area until it is surgically clean. Wipe the area down with laquer thinner, or spray it with contact cleaner. Next, take a pointed dremmel, and grind a "V" groove the entire length of the crack, roughly 1/16" deep. Next, spray/wipe the area down again. Then do the JB thing. Let it cure fully, then refill the oil and see how it does. Hopefully, the crack isn't "walking" on the ends, or it will travel until it finds an end. Stop-drilling is an option, but it doesn't always work.

 

[zio]

Stop drilling is when you drill a small hole at each end of the crack, right? What about the existing JB? How do I remove it without worsening the crack?

 

[biglou]

Ah, I forgot about that. Carefully grinding it away with the Dremmel is my only thought. I've never ground JB, but it will be important to know when you are through the JB and into the Alum. And yes, stop drilling is exactly what you described. It would take a pretty defined crack to be able to do that. I would drill through the case, and JB the entire thing. I repaired a buddy's drain hole on his 99 RM250 that way. I posted pics and all, but with the search function out of wack right now, I doubt I could find the thread.

 

[zio]

I'll dig in & see what I find. Until then, I'm putting my hydro clutch on hold. No need dumping money into a potential lost cause. Thanks, Lou!

 

[Rcannon]

I have never delt with jb weld. Is this stuff really that strong? I better buy some for my toolbox.

 

[BRush]

I once repaired a 1inch hole in my '75 XL250's case with JB weld and a little plastic mesh. It lasted for years.

 

[Rcannon]

I better buy some then. I assumed it was typical hype. Thanks for taking about this. It could save someones riding day, uh, mine!

 

[Dirtvet]

The JB bond is great. I used it to repair a hole in my son's XR 80 gearbox from a thrown chain. Chains tear up aluminum pretty good. It was leaking oil at a spot near the gearshift seal. Just clean it thoroughly, mix the JB Bond, and spread it on. Not another leak. Color even matched the aluminum.

 

[biglou]

JB is a two-part epoxy type material. It dries strong, and bonds tight as long as it is applied to a clean surface. Pretty impressive stuff. I'll see if I can find the thread where I posted pix of the fix to my buddy's bike.

Here it is: Click
I didn't post the pics of the stop drill like I thought I did, but I have them at home somewhere. If I get a chance, I'll post it.