Oh $hit!!

[djg james]

I'm guessing that title has been used before.
I was getting ready to noodle (from both ends) a 3' long Bk. Walnut log That's been on my driveway for a while. It was a catch-all so I cleaned off all the junk. I wear glasses to see detail, but I wear safety sunglasses when I use a chainsaw. I started a cut on top of the log and I immediately got a kick back. I continued the cut and noticed oil was pouring out somewhere. Long story shorter, I had a piece of metal on the log that kicked back and cracked the housing.


Should have been wearing my glasses; then I wouldn't have had eye protection.
My plan is to buy some SealAll from the local parts store first thing tomorrow. After draining the oil and cleaning off the surface, I'd wire brush off the paint. The surface would be roughened up Emory cloth. Final cleanup with acetone and then patch with SealAll. The next day, I'll put on a coat of JB Weld like someone here suggested I use for patching my gas tank.
Sound reasonable? Better ideas?

IF this wouldn't work what are my options?

 

[ericm979]

I'd clean the paint and oil off and use JB weld directly. I have had success patching motorcycle crankcases both Al and MG with it. Drain all the oil and park the saw so any remaining oil is on the other side of the tank, then use a lot of carb cleaner to get the oil out. Then acetone to clean up the carb cleaner residue.

 

[ValleyForge]

This crap is awesome for oils….pardon the pun..lol

 

[djg james]

I tried JB Weld first on my chainsaw gas tank and for some reason it didn't stick. Then someone here suggested SealAll topped with JB Weld for strength.

 

[huskihl]

I’d clean it, rough the surface up, and apply regular 2 part JB weld to it. It’ll last forever

 

[Lionsfan]

I’d clean it, rough the surface up, and apply regular 2 part JB weld to it. It’ll last forever

X2, with heavy emphasis on the clean it part.

 

[djg james]

X2, with heavy emphasis on the clean it part.

Since I have it on hand, I'll try the 2 part JB Weld. I in the process of draining the tank. Not sure if I need to wash out the inside multiple times with mineral spirits. Just keep upright and clean the outside well with MS. That way the walls of the crack will get cleaned so JB Weld will hold.

 

[HansFranz]

I tried JB Weld first on my chainsaw gas tank and for some reason it didn't stick.

Epoxy doesn't adhere well to a lot of plastics. (Some plastics such as polyethylene are technically waxes.) But if you sand and degrease the metal well, it should stick to that just fine.

I would use something more volatile than mineral spirits to degrease...acetone, brake cleaner, lacquer thinner, something like that.

 

[ericm979]

I'd clean the paint and oil off and use JB weld directly. I have had success patching motorcycle crankcases both Al and MG with it. Drain all the oil and park the saw so any remaining oil is on the other side of the tank, then use a lot of carb cleaner to get the oil out of the spot to be repaired. Then acetone to clean up the carb cleaner residue.

 

[ericm979]

Sorry I was not clear- you use a lot of solvent on the spot to be repaired (on the outside), not inside the tank. The surface you apply the epoxy to needs to be super clean. I edited my earlier post to make it clear.

 

[djg james]

Epoxy doesn't adhere well to a lot of plastics. (Some plastics such as polyethylene are technically waxes.) But if you sand and degrease the metal well, it should stick to that just fine.

I would use something more volatile than mineral spirits to degrease...acetone, brake cleaner, lacquer thinner, something like that.

edit: Forgot to mention, this is an Al housing.
I always use mineral spirits or white gas to degrease and then acetone to remove the residue left from the mineral spirits. Then I let it back in the sun for an hour.

 

[djg james]

I wire brush off a wide area around the hole. Then I went ahead and washed the inside three times with portions of mineral spirits. The last time I drained the MS through the crack to wash it out. I roughed up the surface with Emory cloth and wiped down the whole area with a liberal amount of acetone. I let some of it run back into the tank to rinse off the sides of the hole.

After baking in the sun for an hour, I mixed up the JB and applied it over a wide area and into the hole. During drying, it dimpled a little, so tomorror morning, I lightly sand the JB, quickly wipe down with acetone to remove the dust, let dry and apply a second coat of JB. The next day, I sand it flush and spray on some paint.

Here's a shot after clean up. For some reason the shinny metal (Al) area shows up yellow. I tried to correct it, but couldn't. Use your imagination.


Looks like I over corrected.

 

[BrettS]

I would have pulled the saw down, beat the hole flat from inside the case half and had it welded, couple hrs and your back in business but that's just me.

 

[cookies]

I would rough sand it again using 40-80 grit and reapply leaving the jb weld alone and not attempt to sand it flat. If you want it perfect tear the saw down and bake the case at 450 to burn all of the oil out of the aluminums pours and have it tig welded or preferably filled with a torch and aluminum rod or find a used case.

 

[HansFranz]

I would never weld something like that (and I'm a tig welder who owns a machine). Too much work, expense and risk vs. reward, compared to an epoxy repair, which should be fast, cheap and 100% effective/successful, IMHO.

One important thing: Epoxy needs to be "deblushed" to remove a film of amines before painting. So don't forget to sand (or at least scrub with Scotchbrite and water) before painting, or you may have problems with paint adhesion.

 

[djg james]

I would rough sand it again using 40-80 grit and reapply leaving the jb weld alone and not attempt to sand it flat. If you want it perfect tear the saw down and bake the case at 450 to burn all of the oil out of the aluminums pours and have it tig welded or preferably filled with a torch and aluminum rod or find a used case.

That was Plan B (take it apart and have it welded) and C (new Used case). Let's hope Plan A works.

 

[djg james]

I would never weld something like that (and I'm a tig welder who owns a machine). Too much work, expense and risk vs. reward, compared to an epoxy repair, which should be fast, cheap and 100% effective/successful, IMHO.

One important thing: Epoxy needs to be "deblushed" to remove a film of amines before painting. So don't forget to sand (or at least scrub with Scotchbrite and water) before painting, or you may have problems with paint adhesion.

Even if I had a TIG welder or knew where to have it done, I wouldn't do it either. I have no experience tearing a saw down, little intimidating, and I would worry about case warpage from the heat (don't know if that's a problem when TIG welding Al.

Really about the amines. Are the epoxy molecules polarized and the amine moiety floats to the outside while curing? Paint wouldn't adhere to the epoxy? I know nothing about the structure of epoxies.

 

[HansFranz]

Really about the amines. Are the epoxy molecules polarized and the amine moiety floats to the outside while curing? Paint wouldn't adhere to the epoxy?

I don't know whether the molecules are polarized nor what "moiety" means.

Many if not most epoxies have a by-product, or excess component, in the hardener that rises to the surface when it hardens. This is called "amine blush," it's water-soluble, and it can cause problems with paint (or gelcoat) adhesion, yes. BTDT with boat repairs. (If you apply subsequent coats of epoxy while the first coat is still "green" however, you don't need to deblush and the subsequent coat(s) of epoxy will chemically bond to the "green" epoxy, rather than just mechanically bonding which is what happens if you let the first coat completely cure, then sand, then apply more epoxy.) Polyester (Bondo, gelcoat, etc.) type fillers also need to be sanded or knocked down with a Surform before applying more or painting, but for different reasons.

Google "amine blush" and/or "deblushing epoxy for paint prep" for more. (You can clean wet or "green" epoxy off your hands with vinegar, which reacts with -- IIRC -- the basic amines and transforms the whole mess into an emulsion that can be washed off with hand cleaner/soap. But vinegar also makes the amines more likely to migrate through your skin, potentially causing "epoxy sensitization," which is similar to an allergic reaction, so be sure to wash it off fast after using vinegar. And whatever you do, don't contaminate your good epoxy resin or hardener with vinegar, because it will ruin it!)

For everything you ever wanted to know about epoxies and more, I would recommend the wizards at West System / Gougeon Brothers. Their R&D and tech support is the best in the business.

 

[rocketnorton]

gonna guess that case is mag, not alum

no matter til ya try n weld it

 

[HansFranz]

...and AZ92 mag tig filler is like $100/lb...or (let's say) $100 per 1/16" x 36" piece after Bidenflation.

I'd use a dime's worth of poxy and call it "good" for the next 3-4 lifetimes.