Whether or not it can be welded isn't really the question. Anything can be welded. In fact- in most cases, the weld will be stronger than the original material. The problem is... when you weld something, especially aluminum, it will warp a small amount in the process. In a precise part like a crankcase- this can set you up for continued failures if the crank cannot seat into the bearings properly because the case is out of line. It really depends where the crack is, and what part of the case it involves. In the end, you might just be better off rounding up a new crankcase, or better yet, a short-block from seadoo clinic- they are an advertiser on here I believe. This will give you the assurance that when you put everything back together and spend all the money and time on gaskets and new pistons, heads, etc... that you will have a solid foundation, and won't just be doing it all over again in another year when the "repaired" case ends up giving up on you.... 100 mi from nowhere. I don't know about you, but that's usually how my luck goes...

Anyways- just my .02$

 

my buddy's sled had cracked the case also, 03 800, he then went on to blow the crank 4 more times before selling it to me, i put new cases and dropped it in my 440 rev chassis, been runnin strong since

 

Try JB Weld on the outside. The putty version should work fine for you. I have been using for years and did a similar repair to my YZ250 2-stroke. Has held like iron.

http://jbweld.net/index.php

 

My buddy used JB-Weld on the crankcase of his 2001 Arctic Cat Mountaincat 800. When he bought it, the original owner blew a connecting rod through the case (supposedly a notorious manufacturing flaw for this engine) and he sealed up his case with that. A few hours of use later, he discovered he had been running 100 on a compression test, he was leaking coolant, and this eventually lead to a seize after an hour's worth later. If you use it right, I could see it working. I use to use it on fuel lines that wouldn't fit on dirtbikes and such. When you mix it right it is hard as a rock and really durable. I could eventually see myself using it on a case, but if you do, make darn sure you know what you are doing. But then agian you should also be wondering if you should even just buy a new case?

 

Long story short I also ended up with a crack directly on the bottom of the lower case on the mag side. What we did was bolt both case halves together so they would not warp then a friend of mine welded the crack, the crack was fairly bad i might add. stuck it back together and is working great... tested it for leaks with water then carb spray after we got it running and there seems to be no leak, both spark plugs are the same in color also.

 

I've had cases welded before and never had a problem, my last one dropped a skirt and did major damage. You just have to find a welder/machinist who knows what he's doing.

 

That's just it. Finding someone to do it CORRECTLY and as already stated, where EXACTLY is it cracked. If you have deep pockets I guess you could invest the time and money welding it. Might end up doing it again. Remove the crack from the equation and a proper engine build = piece of mind.

FWIW, out here on the on the praire, a breakdown in the middle of nowhere could become a life or death situation--fast.

 

I am a welder and a crack is no big deal just make sure that you take it to a shop that works with mostly aliumum and stainless materials i have welded trannies engine blocks just dont take it to some back yard hack that thinks because he has a welder he is a welder its not always the weld its the prep to do the weld ie drilling the end of the crack so it cant spread cleaning the case with acid bolting the haves together before welding good luck a good tig weld should fix you right up

 

There ya go.

 

JB Weld is AWESOME stuff too.... Fixed Heat exchangers, V8 Chevy blocks, Bike cases, you name it. I can even use it as a filler before Powder Coating!!

 

Hey guys, my friend is taking his motor out of his 03.5 morgan and putting it into his 440. When we were cleaning up the motor we noticed on the mag side right near the top of the bottom case, there is a quater inch hole right beside the ring where your recoil bolts to. Almost looks like the recoil shot somthing out?? Motor ran fine in the morgan so its not causing any performance issues, but the hole is starting to crack in towards the stator. From this post can he just JB weld it and be good to go any input needed asap please thanks

 

i fixed a dime size hole in a crank case on a 97 vmax 700 back in 2001 with jb weld 8 yrs 3000 miles later still going strong! last ring change i noticed the gas was breaking it up so i re did it with 3m panal bond good stuff! i repaired heat exchangers with it as well never had any problems... any local body shop would have some i wouldnt think twice about repairing it with panal bond!

 

I used jb on the case of my mx bike years ago....worked great. Just make sure the area is cleaned real good, and let it fully cure before using the sled. I guess it really depends on where the hole is and how big it is...

 

I'm a welder also. I have welded and used JB weld. Both have there places to use them. You should drill the ends of the crack before you do either. If you JB weld clean and clean it again. Go to a weld supply place and get some aluminum cleaner. If you JB weld it grind the crack out so you can get it in there better than just laying on top of the cases. If you can post a picture so we can see it I can give you a better answer.