Don't leave your magnesium in a swamp

[Oldtoolsnewproblems]

Meant to only take pictures, but I ended out bringing it home in a moment of weakness. Saw this saw and it looked cool, but the magnesium panels had bloomed all to heck from sitting in water so I figured it was all junk, but at the last second I realized the bar looked like it had zero wear side from corrosion, and everyone needs a backup-backup spare bar right? Really need to just pitch it, there are three other saws on the bench ahead of it for rebuild

 

[Woodslasher]

Plenty of parts could be stripped off of that, in my opinion, but it is pretty rough.

 

[Oldtoolsnewproblems]

Yeah I might offer it up for parts, I promised myself I'd scrap it but looking closer, it probably had 2 tanks of gas thru it then it sat on the floor of a leaky shed for how many years. Zero wear on it, but corrosion horizon to horizon. Hate to see it, feel like a monster not giving it a chance tho, it's got a commemorative sticker and everything!

 

[HumBurner]

That was the b-side to John Hartford's, "Dont Leave Your Records in the Sun"....just not as catchy

 

[MacAttack]

Maybe it's just me but I wouldn't count that saw out until I peeked in the cylinder. Does it turn over?

 

[Clyde85]

If it looks rough you won't be afraid to use it a bit.

 

[old CB]

Might not have been a swamp that attacked your saw. I bought an old Mac (a nostalgia saw, as it's the same one I started with in the '70s) that the magnesium was somewhat cancerous from sitting on a concrete floor for years. Concrete will react chemically with magnesium, and perhaps other metals.

 

[rwoods]

7-10s have quite a following over in the McCulloch sticky thread.

Ron

 

[MacAttack]

Might not have been a swamp that attacked your saw. I bought an old Mac (a nostalgia saw, as it's the same one I started with in the '70s) that the magnesium was somewhat cancerous from sitting on a concrete floor for years. Concrete will react chemically with magnesium, and perhaps other metals.

Yep I have some with pitting where they sat on concrete but the internals were clean.

 

[Canyon Angler]

Is there any way to stop that magnesium corrosion once it starts? I have a Skil worm gear saw that apparently was stored on concrete, and it has that kind of corrosion. I slobbed over the corrosion with some motor oil hoping that it would penetrate into the corroded pits and pores and "seal" it away from oxygen, but I don't know whether that's a long-term fix. Maybe degrease it real well with brake cleaner and then coat it with epoxy??? Would that stop it?

 

[MacAttack]

Is there any way to stop that magnesium corrosion once it starts? I have a Skil worm gear saw that apparently was stored on concrete, and it has that kind of corrosion. I slobbed over the corrosion with some motor oil hoping that it would penetrate into the corroded pits and pores and "seal" it away from oxygen, but I don't know whether that's a long-term fix. Maybe degrease it real well with brake cleaner and then coat it with epoxy??? Would that stop it?

Regular paint?

Or POR-15 if you want a seriously good corrosion-proofing paint.

 

[Canyon Angler]

Regular paint?

Or POR-15 if you want a seriously good corrosion-proofing paint.

Thanks! I always heard that magnesium corrosion was like cancer and there was no way to stop it...I guess I heard wrong!

Do you need to sand all the corrosion off first? What about the pits? They look like they go pretty deep...

 

[Oldtoolsnewproblems]

That's true, sitting on concrete will do the same thing. Concrete absorbs more water than people realize, so it can be quite humid right on the ground from underneath. Also concrete tends to be a bit acidic, so that don't help either.
In a former life I rebuilt VWs and you'd get the odd core from time to time that looked perfect until you flipped it over and saw only 2 if the 8 simp studs were still there because the block was swiss cheese below the belt


STOP TRYING TO TRICK ME INTO FIXING THIS this

 

[Woodslasher]

Yeah I might offer it up for parts

Just do that and your problem will be solved.

 

[Oldtoolsnewproblems]

Wait this is a 70cc saw? I thought it was just old and heavy....

Damn you guys, now I have to give it a chance. It really looks like it's never really been used

 

[old CB]

Check out the insides. If the damage did not migrate internally, you might have a cool old beast. Depending on how much you want to put into such a project, that thing might have potential.

Of course it could be the equivalent of certain old pickups, once strong but now a rustbucket, a hole into which you pour money. Could be either.

I've run across old McCulloch saws that were barely run before being stored for decades. It all comes down to how much restoration is required . . . to get you a saw that will make your hands numb in an hour.

 

[rwoods]

... .

I've run across old McCulloch saws that were barely run before being stored for decades. It all comes down to how much restoration is required . . . to get you a saw that will make your hands numb in an hour.

An hour!!! You must be a lot tougher than me - I can only go one tank with my MAC PM700 before my left hand dozes off to sleep.

Ron

 

[MacAttack]

Thanks! I always heard that magnesium corrosion was like cancer and there was no way to stop it...I guess I heard wrong!

Do you need to sand all the corrosion off first? What about the pits? They look like they go pretty deep...

I live in the "rust belt" so fighting corrosion on cars and other things is a necessity, and I'm always trying new things. I would remove all of the visible corrosion, sometimes you need some elbow grease and a small metal bristle brush. The most thorough way is to strip it down and sandblast the housing.
Of all the paints I have tried POR-15 is by far the best rust-proofing and corrosion stopping thing I have tried. It is expensive and NASTY stuff. It has a very thin, runny consistency and will literally stain your skin for weeks. It hardens into almost a plastic and is tougher than hell. I use a small, cheap brush to apply it because I haven't found anything that will clean the brush. If I put it in a coffee can of gasoline it still hardens. It soaks into whatever you put it on and sticks like crazy, it doesn't bubble up or get brittle. It makes Rustoleum look like finger paint.

 

[Oldtoolsnewproblems]

How on earth do they sell this for 2 years only, and manage to make one with and without a chain break? It's like they want me to be confused

 

[rwoods]

How on earth do they sell this for 2 years only, and manage to make one with and without a chain break? It's like they want me to be confused

Welcome to the world of McCulloch. Ten Series MACs were built for years and have so many interchangeable parts that many of us don’t know what we have. We call them Frankenmacs. It is thought that there may be more than a few factory built Frankenmacs.

Ron