JB Weld a crankcase?

95RXL · Mar 1, 2009

Any one ever tried to cover a small crack in a case with JB weld?
Curious if it would adhere to aluminum and expand and contract the same.
A guy in the Arctic Cat thread has a crack and wants to know how to fix it.

Yammerhead · Mar 1, 2009

It would depend on what caused the crack. If it was a one time failure that created the crack or hole, then it would probably work. If the crack was going to continue to be stressed, then I doubt it would hold up.

I have seen JB used to reair a hole in an aluminum head after a valve dropped and was punched back through the head. It's tough stuff, but still has limitations.

:beer;

m1000snowman · Mar 1, 2009

no

i did it, and its a no go

couch · Mar 1, 2009

Had a Exciter jet boat that previous owner(S) had fixed the case with JB or similar - that we ran for a season (didn't know the hole it existed when purchased) without a problem. Ended up swapping the motor out next season with a PMCNA / SBT short block.

m_beeson · Mar 1, 2009

IT WONT WORK You could try to TIG it, but even that is sketchy

You might as well start looking for a crank case right now. That is what it will come to.

calgarysledguy · Mar 1, 2009

I tryed it on my quad and it didnt work. I just used crankcase sealant and am running it untill she blows Good luck

95RXL · Mar 1, 2009

Okay. Good info. Thanks

Wheeline · Mar 1, 2009

95RXL said:
Okay. Good info. Thanks

It works, you just have to prep the surfaces properly.

snow_knight · Mar 1, 2009

I've heard of people doing in to get by.... and it works.. but i wouldnt use it that way for too long

YZ426F · Mar 1, 2009

I would look at some of the devcon products. And as wheeline said the right prep work.

mattymac · Mar 1, 2009

Wheeline said:
It works, you just have to prep the surfaces properly.

X's 2!

darocketman · Mar 1, 2009

I am a professional tig welder and used to work at a local job shop one thing that I always hate is when someone brings in a case or any other aluminum component that they have tried to fix themselves, cast aluminum is very porous and the jb weld will get into the pores and it is almost impossible to weld. also grinding out the crack is a bad idea unless you use a carbide or HSS burr. the bonding agent in grinding discs leaves residue that you cannot remove without lots of heat.the crack should be drilled out at the ends to stop the crack from growing any further and ground out so a good root face weld is possible. depending on the length of the crack you may need to put tacks every inch or so to keep the metal from moving. I like to preheat the metal before even starting the weld to keep distortion at a minimum. the best way I have found is to put it on a wood stove for a couple hours to heat it evenly or put it in an oven at 300-400 degrees or so for an hour at least. it will remove any residual oil and stabilize the metal for welding. after the part is done the temp has to be brought down slowly. I found that by setting the part back on the woodstove covered with a fiberglass blanket and leaving it overnight works very well by morning the part will be cool and should be as good as new. if you dont do the preheat you may distort the metal and cause bearing failure or poor sealing. ask the shop for samples of welds before you have it done. they should look like nickels stacked and have a shiny finnish to them if they are hazy or have spots in them think about going elsewhere. haze or spots most likely mean poor technique (too much or not enough gas flow, using improper tungsten, or holding torch to far away and trying to do too big of a pass at one time or it could mean poor pre weld prep) either way you do not want to have a leak down the road on it as it could mean a lean condition and melted down top end. hope that helps you...

Rixster · Mar 1, 2009

It works just fine IF you use the slow cure type of jb weld stuff. They make some that is more runny and takes like 48 hours to cure. I used it and t has held for many seasons with no troubles at all. Prep the surface right and your good to go. Just for the info Mine was a hole about the size of a penny out of the bottom of the case as well as cracked about 2 inches.

the dude · Mar 1, 2009

darocketman said:
I am a professional tig welder and used to work at a local job shop one thing that I always hate is when someone brings in a case or any other aluminum component that they have tried to fix themselves, cast aluminum is very porous and the jb weld will get into the pores and it is almost impossible to weld. also grinding out the crack is a bad idea unless you use a carbide or HSS burr. the bonding agent in grinding discs leaves residue that you cannot remove without lots of heat.the crack should be drilled out at the ends to stop the crack from growing any further and ground out so a good root face weld is possible. depending on the length of the crack you may need to put tacks every inch or so to keep the metal from moving. I like to preheat the metal before even starting the weld to keep distortion at a minimum. the best way I have found is to put it on a wood stove for a couple hours to heat it evenly or put it in an oven at 300-400 degrees or so for an hour at least. it will remove any residual oil and stabilize the metal for welding. after the part is done the temp has to be brought down slowly. I found that by setting the part back on the woodstove covered with a fiberglass blanket and leaving it overnight works very well by morning the part will be cool and should be as good as new. if you dont do the preheat you may distort the metal and cause bearing failure or poor sealing. ask the shop for samples of welds before you have it done. they should look like nickels stacked and have a shiny finnish to them if they are hazy or have spots in them think about going elsewhere. haze or spots most likely mean poor technique (too much or not enough gas flow, using improper tungsten, or holding torch to far away and trying to do too big of a pass at one time or it could mean poor pre weld prep) either way you do not want to have a leak down the road on it as it could mean a lean condition and melted down top end. hope that helps you...

This guy is right on the money.. I have spent my fair share of time in a welding shop and all of the above is absolutely correct!!! If you do end up JB welding it you wont have any hope of getting it fixed the right way........... But it might work..

priest lake rmk · Mar 1, 2009

What engine case is he looking for

LEE · Mar 1, 2009

JB weld is good for fixing some stuff that really isn't under constant pressure and stress. You would have to get that case very clean and prepped and then I still wouldn't trust it. Find a good case and get that one welded properly as people have stated above, then you have a backup. If you put JB weld on it you will not be able to fix it correctly later.

m_beeson · Mar 4, 2009

Give me red for trying to help a guy out? Geeeese, somebody must own stock in JbWeld.

Prep it and try it, I just like to fix things right. If that starts to loosen up due to vibration, gas, and oil, and you loose crank pressure, and start running lean; Well we all know what comes next...

Red, really, red...

rev440alaska · Mar 4, 2009

i used jb weld in my honda cr 125 dirt bike cylinder. it had a big gouge in it from a blown piston. i put the jb weld in there and used it for a whole season with no problems. also have seen it used on an rmk 550 cylinder with good results

sledneck_03 · Mar 4, 2009

a friend of mine cracked his crank case, and even had a hole in his water jacket and he just got it mig welded, all it holds is a couple lbs vacuum. Running strong and this is on a 1000 summit yet. A good welder can weld just about anything these days as long as your pre heat properly and use the right rods. We knew the guy that welded that and it was so quick he didnt even charge him, you shouldnt be charged anymore than one hours labor.

JB Weld a crankcase?

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