stihl crankcase corrosion question

[teddy]

I recently tore open a saw I got from a guy down the street who said it was in the garage when he moved in!
Well it had some water damage, I know I know!!!! But it's FREE. (and I want to tinker with a saw that is not one of my runners, for the experience!)
Here's the question, on a couple of spots were the aluminum had some corrosion is near a gasket seal, can that be filled with any thing(like jb weld)?!?!?!?!?!
Thanks Matt

[Al_Smith]

A common problem when a saw sits on a concrete floor for any time .

Aluminum is what is known as a sacraficing metal .Meaning that through the process of electrolisis it kind of disappears . One component of concrete is called alumina which comes from blue clay .This is the element that causes the problem and the one reason you cannot use aluminum conduit in a concrete slab .Trivia 101 .

So much for the cause .Yes you can repair it with JB cold  weld,usually .Another product that works like charm for just a sealant is Loctite 5900 which a super RTV used in the auto industry in place of valve cover and oil pan gaskets .Kind of pricey though .

[teddy]

Thanks Al (again!)
I have two basket cases (Stihl 090g)
Both have had that water type damage!
Both saws are complete! but need a total work over!
The corrosion is in the crankcase area.
So last night when I opened them up I was a little worried! Just wanted to hear that this could be remedied!!!!
ANY OTHER SUGGESTIONS WOULD BE HELPFUL!!!!!

Matt

[joe_indi]

Matt,

Any semi drying elastomer  gasket sealant which is gasoline resistant should do the job by itself if the corrosion is only skin deep.
If the corrosion is more a bit of preliminary leveling off with some epoxy cement, followed with a rub with fine grade emery might be required.

I dont know about the crankcase of the 090, but the other Stihl saws I have seen have a magnesium alloy crankcase, which do not take too kindly to welding attempts.

Joe
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