Some crankcase repairs.. part 1
These repairs aren't on my Mag2 - they are on a Super - but are typical of what happens on many 045/056 you buy.
1) The dog mounts break out. The mag2 has much beefier mounts so you'll find this damage mainly on the other versions of the 045 and 56.
2) The crankcases crack on the flywheel side up near the top left recoil cover mount screw. The crack progress around the housing (basically tracking the flywheel) until it fails completely.
Dennis will die laughing, but it is possible to make a repair using epoxy that will last forever, and look good..
There are many types of epoxy... I use JB weld because it is very strong, has a long pot life and an extended "putty" state (mold it with your finger after two hours). It's also rated at 500F continuous, and 600F intermittent. Most consumer epoxies are 250-300F, which is not enough when you are close to the muffler.. the 5-15 minute epoxies are NOT high temp or strong.
A couple of points about epoxy - It MUST be mixed in the exact proportions required. Any mis-match on the resins and the excess will remain uncured forever as honeycombed particles in a lattice of the hardened product. This is weaker, makes for poor adhesion and can cause problem when exposed to heat. I'm making structural parts, so this is is really important. Eyeballing the amounts isn't sufficient.
I use one of two methods - mix the entire two tubes, or, use a postage scale and mix half. In the case of JB weld, the proportions are 1:1, and the products both weigh the exact same amount (1 oz per tube). I occasionally mix a small amount using measuring spoons, but it's often less than satisfactory.
The second issue is mixing. Epoxy must be mixed completely. Mix, scrape, mix, scrape, mix, mix and mix... Clean off the mixing tool several times and mix again... There's plenty of time, so don't rush.. let it sit for 10-15 minutes, then mix again.
and.. expoy won't adhere to oil or grease... so degrease all parts several times and use a die grinder or whatever to prepare the surface to virgin metal.
So.. lets fix a few parts...
The case dog mounts:
Epoxy is strong, but not particularly good when it has movement or stress applied to it from a harder material - it will abrade rapidly. Dogs and the mounting bolts are a high stress point. I've seen many mounts "repaired" by simply epoxying in the bolts. Not good on an 056 as you now need to take the muffler off to take the dog off... I like to put things back as they were designed.
One solution is to sleeve the bolt, and use a stainless washer on the dog side. This give metal-on-metal for the dog bolts to mount though, and a metal surface for the dog to mount on. I used a small flanged brass sleeve cut down and drilled for the 6mm mount bolts. Mine were just from the junk drawer, and in this case they came from the MS200t vent kits. Most Stihl shops will have dozens of them as they aren't used once the kit is installed.
Here's the bad bottom mount (super 2):
What it's supposed to look like (mag 2) - note the extra strengthening ribs on the Mag2:
Sleeve pushed though top hole to figure depth. I've already ground back the case and cleaned out the junk. The sleeve depth required is about 5.5mm. Many cases are slogged out to the point where there is a lot less, so build it back up.
The parts ready to install:
In the bottom mount hole before epoxy. It's tricky to get the elevation correct when there is no reference section left, but with a little care and fiddling, it all come together. I'm using the 6mm hex bolt as a pattern. Note that the head is covered in food wrap...
Continues..