Metal composition of 285CD Crankcase?

[Sapo_feo]

Does anyone know the composition of 285CD Crankcase? Is it pure mag, or 60/40 aluminum/magnesium, cast aluminum or something completely different?

 

[Sapo_feo]

So far anything I have found on the case says it is cast magnesium. Does anyone know if it is pure? I am looking at a 285 with a pretty serious case crack and am wondering about welding options. If it's 60/40 alum/mag I could try out some of that HTS-2000, if it's pure or some other alloy I'll pass since mag tig rods are expensive, and so is the guy who uses them.

 

[JHctRednek]

I don't know if this helps or not but....

If I remember correctly we used to check castings being repaired by cleaning a spot with a file, Magnesium will foam if acetic acid (white viniger) is applied to a bare spot of metal, Aluminum will not. Also if you have a scrap of cast aluminum to compare it to the Magnesium will be noticably harder if you can pass a file over it.

IDK about the alloys though..... hopefully one of the gurus will chime in

opcorn:

 

[Sapo_feo]

I don't know if this helps or not but....

If I remember correctly we used to check castings being repaired by cleaning a spot with a file, Magnesium will foam if acetic acid (white viniger) is applied to a bare spot of metal, Aluminum will not. Also if you have a scrap of cast aluminum to compare it to the Magnesium will be noticably harder if you can pass a file over it.

IDK about the alloys though..... hopefully one of the gurus will chime in

opcorn:

Thanks for the info. I haven't found any easy way to tests at home what alloy a case is. I was hoping for a casting mark. AZ91E is the only alloy I have worked with and it is about 9% aluminum. I am wondering if there is such a thing as a casting alloy with 40% or if it's just a sales pitch from HTS-2000. I have noticed that they only have demo videos of solid and clean aluminum and no pot metal, white metal or any of the other metals they claim to braze with ease. Has anyone tried using it on a chainsaw case?

 

[JHctRednek]

Thanks for the info. I haven't found any easy way to tests at home what alloy a case is. I was hoping for a casting mark. AZ91E is the only alloy I have worked with and it is about 9% aluminum. I am wondering if there is such a thing as a casting alloy with 40% or if it's just a sales pitch from HTS-2000. I have noticed that they only have demo videos of solid and clean aluminum and no pot metal, white metal or any of the other metals they claim to braze with ease. Has anyone tried using it on a chainsaw case?

I don't think that I have used it on a chainsaw case but I did test it on the gear drive on an old straight shaft weed eater. It was a test to see if it was as strong as the video. The case was busted at the neck so I brazed it back together and then beat on it with a sledge on some concrete. The casting broke again but not the brazed joint and not near the brazed joint either. I did remake threads with it as well and you can break a 3/8 bolt off just like the video.. so I was convinced. I used it to repair a broken lower on an old 3hp outboard motor. Thats a long story but the repairs held up for atleast two years with no problems (sold that outboad).

But that stuff is expensive..... So most of my repairs are completed with Aladin 3 in 1 which I have repaired a Homelite case with (handle broken off) and pump cases with. I think the Homelite repair has been going strong for about 10 yrs now, the pump has only been a couple years.

I really don't know if HST 2000 is really that much better than Aladin 3 in 1, but I would think so.

If its a crack on the crankcase is it just to seal it up? or is it in one of the mounts?

 

[Sapo_feo]

It's a crack through the dawg bolt holes on the clutch side. I tested some HTS-2000 on an old briggs intake that has snapped in half. The repair looked ok, but the next day I picked it up and it splintered into cubes. Perfect 1/4 cubes. I emailed the company and they said sometimes that happens if the casting is less than 40% aluminum. I don't want my case falling apart. I saw a case half on ebay, but I really don't want to split it and deal with bearings and such. I'm hoping to get a carcass from the saw shop to test on. Since I already spent my money on the HTS I don't think I'll be trying a different brand any time soon. Thanks for the information. It loks like there may be light at the end of this tunnel after all.

 

[SkippyKtm]

Does anyone know the composition of 285CD Crankcase? Is it pure mag, or 60/40 aluminum/magnesium, cast aluminum or something completely different?

So far anything I have found on the case says it is cast magnesium. Does anyone know if it is pure? I am looking at a 285 with a pretty serious case crack and am wondering about welding options. If it's 60/40 alum/mag I could try out some of that HTS-2000, if it's pure or some other alloy I'll pass since mag tig rods are expensive, and so is the guy who uses them.

Your case is pure magnesium. I doubt a 60/40 alum/mag will work, the weld will most likely crack as it cools (ask me how I know!!). I now use AZ92T60 filler rod with a tig process and a cabinet sandblaster using glass bead or silica (don't use anything like "black magic" or the like as it has aluminum oxide which will cause future corrosion) as you must clean both sides and for each pass. It is very important to have the cases free of any contaminants, soaking it in acetone to remove any oil is important. I use the AZ92T60 rod as its the only rod I can find in small quantities from an ebay seller rocketbracket. The stuff is very expensive though as it runs about $79 for 1 pound of rods, although he'll sometimes sell in smaller quantities. If he doesn't currently have any for sale on ebay I would just message him for some.
Generally if the case crack is shorter than 2 inches its worth doing, but if its longer than that, its generally better to find a good replacement case.

It's a crack through the dawg bolt holes on the clutch side. I tested some HTS-2000 on an old briggs intake that has snapped in half. The repair looked ok, but the next day I picked it up and it splintered into cubes. Perfect 1/4 cubes. I emailed the company and they said sometimes that happens if the casting is less than 40% aluminum. I don't want my case falling apart. I saw a case half on ebay, but I really don't want to split it and deal with bearings and such. I'm hoping to get a carcass from the saw shop to test on. Since I already spent my money on the HTS I don't think I'll be trying a different brand any time soon. Thanks for the information. It loks like there may be light at the end of this tunnel after all.

Sounds like you're gonna pass?

 

[Sapo_feo]

I did pass on the 285. The crack started at the dawg bolt hole, but ended around the corner under the lower clutch side muffler screw. I got the HTS to weld up a crack on my 2101, saw the 285 and thought the $75 for the rod and shipping was money well spent. Now I'm not so sure. I don't want to use it on things I need to use again until I can test it on a carcass.

 

[JHctRednek]

I have learned that with pot metal, cast aluminum, magnesium, white metal etc heat is your biggest pain. I try and not hold the heat on only one spot, try and keep it moving and never put the rod in the flame. Gets really tricky on small parts but I know what your talking about with all that time fixing something to have it just fall apart.

Hope things work out for ya with your 2101, I have a 298 and they are one wicked saw :big_smile:

 

[Sapo_feo]

If anyone else ever needed to know the composition of a 285 crankcase I finally found it.

Mg 88.41%
Al 10.58%
Si 0.061 %
Mn 0.249%
Zn 0.695%

From what I've found most of the 1990-99 cases were around 86%, Mg 12% Al and the early cases were 88-90% Mg.