Neutralising Mag Rot

[Vintage Engine Repairs]

Hey guys, has anyone got any advise or info on neutralising mag rot, an old 660 I’m working on has it pretty bad. I’m thinking a soak in bicarb soda / water solution, or if I can find a big enough sauce pan for the cases - boiling it in that same solution for 15-20 mins.

 

[Breckinridge Elkins]

Would that help, or would that make it worse? What about cleaning it with brake cleaner and a stainless brush, then spraying with an etching primer?

 

[WI_Hedgehog]

Magnesium and aluminum lose electrons easily (causing corrosion), so:
+ keeping the metal dry so moisture doesn't accelerate electron transfer,
+ cool (to slow chemical reactions),
+ in a non-salty environment (salt promotes ion exchange),
+ clean (reducing moisture and chemical interaction),
+ and coat the metal with epoxy paint to keep oxygen off (or a hard powder coat, enamel, or at least WD-40 (WD: Water Displacement))
it should be good (or at least "better" in the case of WD-40).

If you think of this as "basic chemistry" it's pretty understandable and not so mysterious.

 

[Vintage Engine Repairs]

Magnesium and aluminum lose electrons easily (causing corrosion), so:
+ keeping the metal dry so moisture doesn't accelerate electron transfer,
+ cool (to slow chemical reactions),
+ in a non-salty environment (salt promotes ion exchange),
+ clean (reducing moisture and chemical interaction),
+ and coat the metal with epoxy paint to keep oxygen off (or a hard powder coat, enamel, or at least WD-40 (WD: Water Displacement))
it should be good (or at least "better" in the case of WD-40).

If you think of this as "basic chemistry" it's pretty understandable and not so mysterious.

Thanks Brad! I’m really looking for ways to get the sap / oils out of the mag.

Edit: or to neutralise it to stop it continuing to cause damage

 

[Vintage Engine Repairs]

Would that help, or would that make it worse? What about cleaning it with brake cleaner and a stainless brush, then spraying with an etching primer?

Hey, hmm I’m not sure, I figured neutralising any of the oil that’s inside the magnesium metal with an alkali would stop it from continuing to corrode? Maybe it’s not necessary, I had just heard in the past that it needs to be neutralised but I couldn’t find the post in question doing a search.

 

[ZeroJunk]

Just throw this out there. Might be crazy. But, wonder if zinc paint would work ?

Whole idea behind a tin roof or anode on an outboard drive is that the zinc will sacrifice itself before the iron or aluminum.

 

[WI_Hedgehog]

Hey, hmm I’m not sure, I figured neutralising any of the oil that’s inside the magnesium metal with an alkali would stop it from continuing to corrode? Maybe it’s not necessary, I had just heard in the past that it needs to be neutralised but I couldn’t find the post in question doing a search.

Magnesium corrodes easily, the best/easiest/fastest cleaning method I've found is Dawn Dish Soap with warm water in the dishwasher. (Water jets are milder than brush bristles.)

Of course you can use a stiff brush and Dawn in a bucket (I use a lot of soap instead of just a little soap, it seems to coat the parts and stop corrosion). I would not use a wire brush which opens new scratches. I rinse with HOT water because it evaporates quickly, and also have a dehumidifier set so the air us under 40% humidity (35% works well).

Oil doesn't "soak in" to metal, though it can fill the pits and scratches; soap can lift it back out.

 

[Vintage Engine Repairs]

Magnesium corrodes easily, the best/easiest/fastest cleaning method I've found is Dawn Dish Soap with warm water in the dishwasher. (Water jets are milder than brush bristles.)

Of course you can use a stiff brush and Dawn in a bucket (I use a lot of soap instead of just a little soap, it seems to coat the parts and stop corrosion). I would not use a wire brush which opens new scratches. I rinse with HOT water because it evaporates quickly, and also have a dehumidifier set so the air us under 40% humidity (35% works well).

Oil doesn't "soak in" to metal, though it can fill the pits and scratches; soap can lift it back out.

Thanks mate, your reply is much appreciated. Oil certainly soaks into magnesium. It’s super porous!

 

[huskihl]

Heat will bring oil out of the pores.

I’ve cleaned it up with carb cleaner and a brush and then covered it with JB weld 7-8 years ago. JB is still there

 

[Vintage Engine Repairs]

Great, sounds like once it’s been washed and cleaned it’s good to go, no need to neutralise it! Thanks guys

 

[WI_Hedgehog]

Thanks mate, your reply is much appreciated. Oil certainly soaks into magnesium. It’s super porous!

You are correct sir, rotty magnesium is super porous, I cede your point, and thank you for bringing that up.

 

[ZeroJunk]

I had an 066 that was used to cut Palm trees. Don't know what is special about Palms, but that crankcase under the clutch drum cover was rotten.

We normally do not see it here, at all.

 

[ballisticdoughnut]

I had an 066 that was used to cut Palm trees. Don't know what is special about Palms, but that crankcase under the clutch drum cover was rotten.

We normally do not see it here, at all.

Seen the exact same thing on a DCS6421 I picked up a year ago. Saw came out of south Florida and was used to cut palm. Cases were in bad shape, ended up rebuilding the saw with new cases and a bunch of other parts. That palm juice is pretty corrosive.

 

[SteveSr]

Calling... @Mad Professor

 

[nedsim]

Thanks mate, your reply is much appreciated. Oil certainly soaks into magnesium. It’s super porous!

I've used stuff called "de-oiling powder" when cleaning oil-soaked cast iron machine tool ways before applying Moglice or Turcite. Turcite is a composite sheet bearing material that's glued on with epoxy; Moglice is a moldable epoxy bearing material. Not sure what the magic de-oiling powder actually is, but it does seem to draw much more oil out than simply cleaning with detergents and/or solvents. Unfortunately the SDS does not reveal much about its composition.

http://www.moglice.com/cleaners---release-agents.html

 

[Vintage Engine Repairs]

You are correct sir, rotty magnesium is super porous, I cede your point, and thank you for bringing that up.

No worries at all, thanks for the advise!

 

[Vintage Engine Repairs]

I've used stuff called "de-oiling powder" when cleaning oil-soaked cast iron machine tool ways before applying Moglice or Turcite. Turcite is a composite sheet bearing material that's glued on with epoxy; Moglice is a moldable epoxy bearing material. Not sure what the magic de-oiling powder actually is, but it does seem to draw much more oil out than simply cleaning with detergents and/or solvents. Unfortunately the SDS does not reveal much about its composition.

http://www.moglice.com/cleaners---release-agents.html

Thanks for sharing!!

 

[farmhard]

Magnesium and aluminum lose electrons easily (causing corrosion), so:
+ keeping the metal dry so moisture doesn't accelerate electron transfer,
+ cool (to slow chemical reactions),
+ in a non-salty environment (salt promotes ion exchange),
+ clean (reducing moisture and chemical interaction),
+ and coat the metal with epoxy paint to keep oxygen off (or a hard powder coat, enamel, or at least WD-40 (WD: Water Displacement))
it should be good (or at least "better" in the case of WD-40).

If you think of this as "basic chemistry" it's pretty understandable and not so mysterious.

Epoxy over mag and aluminum might NOT stick depending on the alloy and manufacturer of the epoxy.

 

[farmhard]

Neutralizing mag has 2 factors imo. What caused the corrosion and why? If the paint was not sealed and moisture did it or was it exposed to acidic compounds. Mag oxidizes almost instantly so most likely a good cleaning in solvent followed by soapy water and final rinse with prime wipe should do the trick.
Brake cleaner may leave a residue same as lacquer thinners. Body shops do not use brake clean or thinners to wash cars, they use prime wipe. Not all generic laquer thinners are the same. Gun wash is another animal.
I just did an 046 which I hydroblasted and then put in the ultrasonic with Dawn. The ultrasonic was cleaned out and the Dawn turned the casting a darker black color,
Baking soda is great, I soak them but you have to get all the residue off. It can leave a coating. I suggest ultrasonic or pressure washing after.
Epoxy often requires etch primer underneath, we are currently having a problem with primer peeling off a 90hp Evinrude as the primer lifts. Most epoxy manufacturers require etch primer UNDER Epoxy on alloys. DTM is not DT all M's.
The aerosol etch primers may lift off with lacquer thinners. Professional etch primers don't come off period.
I have soaked saws in 5 gallon pails of Kleenflo carb solvent, the caustic nasty stuff and it can pit the metal long term and you have to be careful around the water seal.
I would give Pioneer the worst rating for paint adhesion of any manufacturer.

 

[cookies]

Diesel and a parts brush to remove the majority of the caked on sap/oil then soak in hot water with a dishwasher tablet and rescrub with the parts washer brush. Third step dawn soap w hot water, third step might take one time or three just keep changing the water and soaking and cleaning until the water stops getting oily. Rinse and soak with hot water until satisfied everything came off. Blow dry with compressed air, allow to sit in the sun until thoroughly dry then seal it with primer or sand blast strip it and powder coat. I like this stuff for primer because I can start applying paint under a hour later and the stuff holds up to every paint and clear I've shot over it

Transtar 4603​