White Death Corrosion Experts Needed

[Glock37]

I've never used JB Weld inside a crankcase before. Should I be concerned that it can come loose over time and destroy bearings or worse?

I dont like using any filler inside just powder coating


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[Agrarian]

I dont like using any filler inside just powder coating

I'm guessing that I can't do powder coating myself so I would need to find someone who does tiny quantities cheap - I'm thinking that is not likely. I do have a few cans of TSC Husqvarna Orange in rattle cans though.

 

[Tor R]

Barry, there is still corrussion left, at least I can see it on your pictures.

Glock37 has correct, get them sandblasted, there are several industrial painter shop who has cabin for blasting small parts.

Protect all places you dont want them to blast and you save money (special bearing&seal area has to be protected 100%, simple tape aint good enough). If it's just the crank area it's done in 10 minute blasting time.

When your parts is blasted there are several way to rebuild up the quality again, and we can take it from there.

 

[Motorhead]

If rust stop works,I would try ospho,(phosphoric acid) I have used ospho on steel before and it works great,Im not sure about magnesium.

 

[Tor R]

Things who work great in iron doesnt normally work well on alu&mag stuff

 

[Glock37]

If your gonna blast get some old bearings grind a cut into them remove the innereds and insert those in the bearing bores get a stopper and place it in. The seal area on flywheel side Bolt both halves together abd when both sides done thendo inside gently around seal gasket areas


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[Agrarian]

If your gonna blast get some old bearings grind a cut into them remove the innereds and insert those in the bearing bores get a stopper and place it in. The seal area on flywheel side Bolt both halves together abd when both sides done thendo inside gently around seal gasket areas.

I'm sorry, I know there is some great info here and I want to be sure I understand it all.
1. Remove guts from 2 bearings
2. Insert bearings partially into bearing wells. Partially so that it is easy to remove later.
3. Insert a stopper into each hollowed out bearing (from the outside)

Here is where I am confused. Then bolt both halves together and sandblast the inside as a mated pair? Wouldn't that make it awfully difficult to get all the areas given the tight space? I'm thinking I have something wrong. Especially when you go on to say to "then do the inside gently around the gasket areas".

What am I not understanding?

 

[Brush Ape]

What am I not understanding?

Maybe you're retarded.

 

[Agrarian]

Ape on the loose!

 

[Glock37]

I'm sorry, I know there is some great info here and I want to be sure I understand it all.
1. Remove guts from 2 bearings
2. Insert bearings partially into bearing wells. Partially so that it is easy to remove later.
3. Insert a stopper into each hollowed out bearing (from the outside)

Here is where I am confused. Then bolt both halves together and sandblast the inside as a mated pair? Wouldn't that make it awfully difficult to get all the areas given the tight space? I'm thinking I have something wrong. Especially when you go on to say to "then do the inside gently around the gasket areas".

What am I not understanding?

Do outside of case while cases are bolted together Stopper goes in flywheel side of case where oil seal goes to keep blast away from sealing area

Unbolt cases and do inside oil tank and inside crankcase While apart get the areas that where tough to get too while together




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[Tor R]

Barry, we used dutch tape + 1mm rubber tape, dutch tape first, cut it to have nice fitting, then rubber tape, cut it to have nice fit.
You want to mask all surface that you dont want to sand blast.
You can put in those old bearing + seals, instead of doing masking.
If you only want to sand blast crank area you just knock two rod through the seal, and protect the rest of the area, as longer distance from sand blast area as weaker protection you need.

If you want whole cases to be sand blasted dont forget to mount screws so you prevent threads damage.

 

[Agrarian]

Barry, we used dutch tape + 1mm rubber tape, dutch tape first, cut it to have nice fitting, then rubber tape, cut it to have nice fit.
If you only want to sand blast crank area you just knock two rod through the seal, and protect the rest of the area, as longer distance from sand blast area as weaker protection you need..

If I were powder coating the case, I would do the whole thing but I would like to do just the affected areas since the outside of the case is very good and has no visible oxidation. I like Glock37's idea of using the rubber stoppers. Since I only plan to do the inside, I can skip the modified bearing approach and use stoppers or your rod idea to seal the crank bearing bores and use the rubber tape to protect the gasket surfaces.

I want to get a small blaster for my own use - I already have a compressor that should work for small jobs like this. What media should I use? Soda, sand, glass beads, walnuts, corn????

 

[Glock37]

We use 36 grit black beauty. Under the paint you ll find black oxidation its best to do whole case inside and out

Stihl paint sucks its bat
Rely on , husky powder can be a bear to remove in spots , pioneer air will blast it off , you need a good surface to get good adhesion for powder we try between 8-10 mils of powder


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[Marshy]

Corrosion of Magnesium Alloys


Magnesium is the most chemically active of the metals used in aircraft construction and is the most difficult to protect. When a failure in the protective coating does occur, the prompt and complete correction of the coating failure is imperative if serious structural damage is to be avoided. Magnesium attack is probably the easiest type of corrosion to detect in its early stages, since magnesium corrosion products occupy several times the volume of the original magnesium metal destroyed. The beginning of attack shows as a lifting of the paint films and white spots on the magnesium surface. These rapidly develop into snow-like mounds or even “white whiskers.” [Figure 6-17] Re-protection involves the removal of corrosion products, the partial restoration of surface coatings by chemical treatment, and a reapplication of protective coatings.

Treatment of Wrought Magnesium Sheet and Forgings
Magnesium skin corrosion usually occurs around edges of skin panels, underneath washers, or in areas physically damaged by shearing, drilling, abrasion, or impact. If the skin section can be removed easily, this should be done to assure complete inhibition and treatment. If insulating washers are involved, screws should at least be sufficiently loosened, to permit brush treatment of the magnesium under the insulating washer. Complete mechanical removal of corrosion products should be practiced insofar as practicable. Limit such mechanical cleaning to the use of stiff, hog bristle brushes, and similar nonmetallic cleaning tools (including nonwoven abrasive pads), particularly if treatment is to be performed under field conditions. Like aluminum, under no circumstances are steel or aluminum tools, steel, bronze or aluminum wool or other cleaning abrasive pads used on different metal surfaces to be used in cleaning magnesium. Any entrapment of particles from steel wire brushes or steel tools, or contamination of treated surfaces by
dirty abrasives, can cause more trouble than the initial corrosive attack.

Corroded magnesium may generally be treated as follows:

1. Clean and strip the paint from the area to be treated. (Paint stripping procedures were discussed earlier in this chapter, and are also addressed in FAA
Advisory Circular (AC) 43.13-1B, Acceptable
Methods, Techniques, and Practices — Aircraft
Inspection and Repair.)


2. Using a stiff, hog bristle brush or nonwoven abrasive pad, break loose and remove as much of the corrosion products as practicable. Steel wire brushes, carborundum abrasives, or steel cutting tools must not be used.

3. Treat the corroded area liberally with a chromic acid solution, to which has been added sulfuric acid, and work into pits and crevices by brushing the area while still wet with chromic acid, again using a nonmetallic brush.

4. Allow the chromic acid to remain in place for 5 to 20 minutes before wiping up the excess with a clean, damp cloth. Do not allow the excess solution to dry and remain on the surface, as paint lifting will be caused by such deposits.

5. As soon as the surfaces are dry, restore the original protective paint.


Treatment of Installed Magnesium Castings


Magnesium castings, in general, are more porous and more prone to penetrating attack than wrought magnesium skins. For all practical purposes, however, treatment is the same for all magnesium areas. Engine cases, bellcranks, fittings, numerous covers, plates, and handles are the most common magnesium castings. When attack occurs on a casting, the earliest practicable treatment is required if dangerous corrosive penetration is to be avoided. In fact, engine cases submerged in saltwater overnight can be completely
penetrated. If it is at all practicable, parting surfaces should be separated to effectively treat the existing attack and prevent its further progress. The same general treatment sequence in the preceding paragraph for magnesium skin should be followed. If extensive removal of corrosion products from a structural casting is involved, a decision from the manufacturer may be necessary to evaluate the adequacy of structural strength remaining. Specific structural repair manuals usually include dimensional tolerance limits for critical structural members and should be referred to, if any question of safety is involved.

https://www.faa.gov/regulations_pol...craft/amt_handbook/media/FAA-8083-30_Ch06.pdf

 

[Agrarian]

^^^ This is a more detailed version of the chromic acid procedure I posted earlier. If the FAA approves it, it must work. They, like Glock37, also say that it must be repainted to maintain protection. That has me worried because I was hoping that simply keeping an oil film on it would stop the progress. Maybe I do need to look at using some epoxy coating or bite the bullet, blast the whole thing and powder coat it. The cost of that would probably not make sense - I would just part it out.

 

[angelo c]

I'm guessing that I can't do powder coating myself so I would need to find someone who does tiny quantities cheap - I'm thinking that is not likely. I do have a few cans of TSC Husqvarna Orange in rattle cans though.

barry,
do yourself a favor...PM Mike( @Glock37 ) and just ask him how much.
he does this stuff fer a living...

he ain't just innernet spouting off stuff he lernd from the innernets
I dare you to find a member who has done the same and not been overjoyed at the returned product.

 

[Tor R]

If I were powder coating the case, I would do the whole thing but I would like to do just the affected areas since the outside of the case is very good and has no visible oxidation. I like Glock37's idea of using the rubber stoppers. Since I only plan to do the inside, I can skip the modified bearing approach and use stoppers or your rod idea to seal the crank bearing bores and use the rubber tape to protect the gasket surfaces.

I want to get a small blaster for my own use - I already have a compressor that should work for small jobs like this. What media should I use? Soda, sand, glass beads, walnuts, corn????

you can remove the paint in crank area, same way you already have started, and get the whole paint away, just take your time.
You can buy a cheap sandblaster tool for cars, on small things like this it will do the job without any doubt.
We used furniture sand when we blasted aluminium, but you may go for a softer sand materiale since it's magnesium, but I never really sandblasted so much, mostly I was industrial painter.

When you are done sandblasting I would paint a thin layer epoksy primer, let it cure, filled the holes with epoksy sparkle and make things smooth, and finished the whole project with a bit thick layer epoksy paint.
Just make sure the paint is chemical resistance.

That said, I would probleby take the easy route and find a nice crankcase

 

[Glock37]

Some of the saws we powdered


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[Glock37]

2100 and a solo twin also a 064 before powder all masked off


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[exSW]

I had my 2186 Jonsered powder coated by a local guy. Does a LOT of Harley stuff. Did everything above mentioned and it was his first saw.$100.00.