Cracked Crankcase

[ChimneySmoke]

Hi All,
Picked up a flat top 066 a while ago. Used it a few times but when I got around to giving it a good cleaning I discovered this crack in the crankcase. The break is really visible below the top bolt hole, runs under the brake band, then don`t see it anymore. Further down, below the brake band anchor it appears again but only for about half an inch.

I don`t use the saw professionally, just for personal firewood. This saw by no means is a collector but just a tool i would like to keep for a few years. Any recommendations and opinions on the best way to deal with this is appreciated. Thanks in advance.

 

[a. palmer jr.]

I guess it won't hurt anything unless it's cracked into the crankcase causing it to run lean. It appears to be in a place where a fix would be difficult.

 

[ChimneySmoke]

Its running on the rich side now so i don't think its going into the crankcase. But defineatly something to be aware of. I wouldn't want to loose the oem top end. Thanks APJ!

 

[a. palmer jr.]

There are some places on those saws that don't look like they could be welded but a person could always replace that side of the case. It's a little work but can be done..

 

[blsnelling]

That crack doesn't appear to be at risk of going inside the sealed part that would affect the engine. I say use it until it becomes a problem. You may get many more years out of it.

 

[glock37]

Hi All,
Picked up a flat top 066 a while ago. Used it a few times but when I got around to giving it a good cleaning I discovered this crack in the crankcase. The break is really visible below the top bolt hole, runs under the brake band, then don`t see it anymore. Further down, below the brake band anchor it appears again but only for about half an inch.

I don`t use the saw professionally, just for personal firewood. This saw by no means is a collector but just a tool i would like to keep for a few years. Any recommendations and opinions on the best way to deal with this is appreciated. Thanks in advance.
View attachment 700937

The best solution is too tear it down send too shawn carr have him weld it then to me for powder then reassemble and no more worries


Sent from my iPhone using Tapatalk

 

[user 122190]

Epoxy and use compressed air to force it deep into the crack.

 

[grizz55chev]

Epoxy and use compressed air to force it deep into the crack.

It’s open behind the crack, I’d epoxy from behind and run it. Pull the fuel tank assembly and get to gluing!

 

[user 122190]

It’s open behind the crack, I’d epoxy from behind and run it. Pull the fuel tank assembly and get to gluing!

I glue most everything. Under appreciated, but effective and inexpensive. In some cases glue is stronger then the original. Think laminated wood.

 

[a. palmer jr.]

I thought about the epoxy but thought it might be difficult where the crack is...

 

[user 122190]

I thought about the epoxy but thought it might be difficult where the crack is...

It sounds like the saw is OK, as is (for now). The epoxy might slow or stop the crack from getting larger.

Do remember that some epoxy can be brittle where it is not tightly compressed between the 2 surfaces. In such a case, in building RC Airplanes, we would shred fiberglass cloth to mix with the epoxy.

In working on a saw, do it once do it right. A second go at it would be harder, if you were to attempt a second repair over the first.

 

[drf255]

Run it as is as long as you can, which will be a long time IMHO.

 

[Canyon Angler]

I would degrease the piss out of it with brake cleaner and compressed air. Then mix up some unthickened epoxy resin, thin it (by up to 10% by volume) with acetone, and work it into the crack with a small brush if possible. Then add more unthinned, unthickened epoxy on top while the underlying epoxy is still "green" (not hardened). Loctite epoxy in a double-syringe ($3 at Walmart) should be fine for this, just be sure the first layer doesn't harden up before you add the second layer...it hardens fast!

After everything is hardened up, deblush it with Scotchbrite and water, then paint to protect the epoxy from UV. Or you could mix in a little UV-blocking filler (powdered metal or graphite would work) to the 2nd coat, and that would shield it from UV, but you'd probably still want to paint it to hide the (black) epoxy composite.

The most critical thing for a good bond is getting the initial tack coat to wet out to clean metal well.

 

[ChimneySmoke]

Thanks for some excellent feedback. Welding is not an easy option for me so I like the idea of epoxy and run it. Great suggestions on how best to apply it. Planning on taking the tank off and cleaning this weekend. Selection of epoxies here are are limited. Walmart sells the gorilla brand in the double-syringe which is probably the most fluid. As for regular epoxy my choices are Lepage or JB Weld. I have some aluminum reinforced epoxy putty but that doesn't sound like it can be worked into the crack enough to provide a decent bond. Thanks again, really appreciate the advise.

 

[Jasonrkba]

There may be some ideas on this thread that can help you.

https://www.arboristsite.com/community/threads/whats-your-best-mcgyver-repairs.303832/

 

[user 122190]

Thanks for some excellent feedback. Welding is not an easy option for me so I like the idea of epoxy and run it. Great suggestions on how best to apply it. Planning on taking the tank off and cleaning this weekend. Selection of epoxies here are are limited. Walmart sells the gorilla brand in the double-syringe which is probably the most fluid. As for regular epoxy my choices are Lepage or JB Weld. I have some aluminum reinforced epoxy putty but that doesn't sound like it can be worked into the crack enough to provide a decent bond. Thanks again, really appreciate the advise.

JB Weld is great stuff, but is really thick. You can likely get enough into the crack, but because it it so thick, I doubt it would flow back together to fill any air pockets that would naturally be created. The gorilla is also great stuff. The only thing about the Gorilla is it can expand, and possibly create problems else where, like that clutch tension bar that is close to the crack. Maybe not, but something to think about.

For another option, check out a hobby store. I use to buy epoxy of 5, 15 or 30 minute set times as per my use and all were very viscous and easy to work with. Get something that seems like it would flow easy, and thicken it up with shredded fiberglass, or something similar til you can get it just right.

 

[rocketnorton]

There are some places on those saws that don't look like they could be welded but a person could always replace that side of the case. It's a little work but can be done..

+1

 

[grizz55chev]

+1

Mismatched case halves is not recommended.

 

[rocketnorton]

no, but is done somewhat regularly...

 

[ChimneySmoke]

Got the tank off and de-greased n cleaned as much as possible. blsnelling was correct in that the crack does not appear to be going into the sealed part of the engine. But it is long and zig-zags all over the place. Going to go ahead with the epoxy using the methods recommended. Welding is out so nothing to loose! Also considering using the dremell with a carbide burr to slightly V out the crack on both sides where possible.