Repaired one problem, created another. Any ideas how to solve?

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Hi all,I recently repaired some broken out holes on a motorcycle crankcase .  The area where the cover bolted on had two broken out holes and a crack alongside the bottom near where the case splits.  I was able to successfully repair the broken out holes and repair the crack but in doing so I burned out the sealant in between the case halves leading oil leaking out.  does anyone know a way to repair this?  Is there some type of high temp sealant that can be applied?Years ago I stopped welding on riveted boat hulls for the same reason and found a sealant that penetrated the joints via capillary action and whenever someone called me to seal weld rivets, I pointed them to that product.  However this has to be a high temperature application as the crankcase gets sizzling hot when running.Thanks for any help,Tony
Reply:Never Heard of anyone managing to reseal such a leak in a reliable way. I'd rip it apart and do it right, unless it's a $100 bike I just want some more fun on before tossing it in the scrap metal bin.Last edited by G-son; 08-10-2015 at 05:57 PM.
Reply:You are certainly an ambitious cuss, that's for sure.  What sort of motorcycle is that?  I recently removed the accessory case off the back of a Lycoming O-290 that had several built up layers of hard setting permatex on the mating surfaces.  It seemed to hold oil for the most part, for a Lycoming anyway.Let me add though, you'll pay hell trying to get the case halves back apart once you've glued them together like that.  I used heat and careful pry-tation to get that case off there.Last edited by skyboltone; 08-10-2015 at 06:17 PM.DanI hope that when i'm dead and gone, people will remember me and think; "Boy, that guy sure owed me a lot of money!"
Reply:It shouldn't get to more than a couple hundred degrees, so not really high temperature. Any silicone product will work. The trick is to get it in  the joint, not just on the surface. I have had the best luck sealing up the case, then connecting a vacuum source, vacuum pump, engine manifold vacuum, etc. then,spraying it with brake cleaner, then pushing the silicon in there. Has worked on more than one occassion.
Reply:That sounds very promising.  Did you apply the brake cleaner on top of the silicone after applying it to the joint?  Did this thin it out and make it possible to seep into the crack?  I'll try it. thanks,Tony
Reply:Good old brown liquid gasket shellac....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Permatex Form-A-Gasket sealant:http://www.permatex.com/products-2/p...sealant-detail
Reply:Thanks for the reply fellas.  Problem is that this has to be sealed without taking it apart.  It seems like a major project taking the motor out of a Kawasaki motorcycle and splitting the case and then reassembling it.  Anyone done it?  How lone should I expect it to take?  If it comes to that, I'll do it but reluctantly.  There must be some type of sealant designed for this situation?  NO?   Walker's suggestion to us silicone sounds very doable but is there anything made specifically for cases like this?
Reply:The brake cleaner was sprayed first to get the oil out of the joint. The silicone goes in pretty well just by forcing it into the joint, add the vacuum and it draws it into even the smallest cracks.
Reply:If you want the absolute best RTV type sealer that gets firmer than regular silicone RTV, then try The Right Stuff.  If you get the case clean enough, The Right Stuff will seal it (unless the case builds up a lot of internal pressure.)  Available at all car parts stores.  Case halves for motorcycles are machined to such close tolerances that you almost don't need a sealer in between (of course we all DO seal them because it's the only way to be sure you don't have a leak).  I usually use an anaerobic sealer that seals when deprived of air.  If the case is leaking badly, I would imagine it got warped during the welding process ( or maybe when the guy wrecked it causing all the damage that you had to repair), so I'm not totally convinced that your repair actually burned up the sealant on the mating surfaces.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:The case joint is a precision machined surface,  the sealant used only fills minute imperfections.  I would suspect the case is warped.Sent from my iPhone using TapatalkBriggs weldnpower 225/210/cvLn-25 suitcaseMillermatic 130
Reply:To me - being more of a mechanic and not so much a welder, it does not seem like a big deal at all. Sounds much easier than the machining you did anyway. Pretty sure what you want to use there (once taken apart) is a permatex/loctite 515 sort of thing. A thin bead and you put the part together under the torque specs, removed from air it cures. On the boat rivots - been through that and never though of trying to weld it, but never had any luck with sealant, or at least when salt water is involved. Sooner or later the aluminum seems to corrode and break the sealant free. What does work well though is simply removing the offending rivot and replacing it with a truss head screw bolt, using aluminum washers on each side and a nylon locknut (with a little sealant around the bolt/washers/nut is OK, doesn't hurt).  Another thing is probably just to get the right industrial rivot setup and replace them but never tried that or seen one used. Those old thin aluminum hulls though definitely do not take to welding well, seen that fail before. Jon
Reply:I kinda doubt Locktite 515 will seal a machined face that has warped by welding.  Just my opinion though.  I hope I'm wrong.DanI hope that when i'm dead and gone, people will remember me and think; "Boy, that guy sure owed me a lot of money!"
Reply:Originally Posted by skyboltoneI kinda doubt Locktite 515 will seal a machined face that has warped by welding.  Just my opinion though.  I hope I'm wrong.