brigs and straten engine case, magnesium ?? aluminum??

[fun4now]

i have a 17HP B&S mower engine casing i needed to weld up a few cracks on.
i was told its cast aluminum, but seriously doubt it. i went to TIG it up like i have on many bike case's and got very different results. it kept popping out lil yellow specks or pebbles like salt sized, and popping. no way to get it to flow. just as it would get ready to go liquid it swell and would pop out junk. the only conclusion i could come to was its not aluminum but magnesium. any ideas on how to weld some thing like this or do you just get an aluminum brazing rod and go that way??? this thing just refused to accept heat without exploding?? i ended up using a brazing rod on it and got it to seal up. is there a better way?? i was thinking if i had to put a piece back in and seal it up i don't know that this would be an option ?? any of you guys deal with this stuff, if so whats the trick ??

the pic's are befor i cleaned it up to weld. it was spotless when i started adding heat, thats just the way i got it.

[Aerometalworker]

i have a 17HP B&S mower engine casing i needed to weld up a few cracks on.
i was told its cast aluminum, but seriously doubt it. i went to TIG it up like i have on many bike case's and got very different results. it kept popping out lil yellow specks or pebbles like salt sized, and popping. no way to get it to flow. just as it would get ready to go liquid it swell and would pop out junk. the only conclusion i could come to was its not aluminum but magnesium. any ideas on how to weld some thing like this or do you just get an aluminum brazing rod and go that way??? this thing just refused to accept heat without exploding?? i ended up using a brazing rod on it and got it to seal up. is there a better way?? i was thinking if i had to put a piece back in and seal it up i don't know that this would be an option ?? any of you guys deal with this stuff, if so whats the trick ??

the pic's are befor i cleaned it up to weld. it was spotless when i started adding heat, thats just the way i got it.

James,
Ive welded quite a few briggs blocks, and have the material specs on the casting material. No its not magnesium. What I can tell from the picture is that it wasnt clean enough. This is a porous die casting, and the only reliable way I have found to weld them is to get them squeaky clean in the ultrasonic cleaner, vee out the base metal to 75% depth, preheat to 350-400 F, and weld using either 4043 or 4047 filler. Tig works OK, torch works a bit better due to the flux, but I usually use the Tig technology.
-Aaron

[fun4now]

yea i cleaned it a bunch more than in the pic. even took a torch to it lightly to bring out any oil that would seep out when i start to weld. acitoned it after a serious decreasing. i have just never had little specks come out wile welding that burned off with yellow smoke trail on the work ?? it was definitely not responding to any of the tricks i use on motorcycle covers. it was really frustrating.
the guy has another one thats too far gone to try to fix. so i asked if i could have it to work out a way that works. i was thinking i would do a little more playing around with the O/A torch on it as well as TIG and see if i can come up with a better solution. it was the first time i did one of these. i was expecting the same from it as a bike cover and was sadly mistaken. i don't like to be beaten so i'm going to keep at it till i can produce great a looking solid repair on the spare one. so if it comes up again i will be ready, and if it never comes up again i will still have learned some thing new. and experience is always worth the $$ of consumables.

i don't have an ultrasonic cleaner, any other helpful hints would be greatly appreciated.
i used engine de-greaser, acetone and stainless steel wire wheel. i used the wire wheel by hand not in the grinder so as not to melt anything in or tear out too much. it was clean and shiny and nothing seeped out with heat added. used a heat gun to pre-heat it be for welding.

any idea's??? i need to get this right , even if its just for me.

[Aerometalworker]

James,
In lieu of having an ultrasonic, try an old Nesco roaster filled with a mixture of water and Simple Green Aircraft and Precision parts cleaner. Dont use the regular simple green. Original Tide works as well. Heat the mixture up to steaming, and give the block a bath for an hour or so. You would be amazed at the gunk that continues to ooze out after you think you had it clean. One word of caution, dont try to weld "Hot and Fast", there are low melting point materials in the casting that will boil out easily under the Tig arc. Pre-Heat and take your time.
-Aaron

[FusionKing]

Use the wire wheel in the grinder NOT by hand!! There is no way in **** you will EVER get it good enuff by hand. Get it in the groove and DIG hard so you can actually see the pores smear over.Then heat the bevels untill crud rises and wire wheel again. Use a hand brush for touch up during the process maybe, but that old nasty casting needs you to get very aggressive or it WILL whip you.
If you are going to use a brush by hand use a hand brush with a handle so you can get very vigorous.
The aircraft cleaner by simple green works pretty good but I like superclean as well or better.
Funny thing to me is I get all kinds of super nasty castings brought to me and don't seem to have near that much trouble. I wonder where you had your hz and balance set? I stay more on 50% balance for more cleaning and really don't use much hz either. Old school works much better on castings because you do not want to pound all the junk out out it when you weld. Sometimes I drop WAY down on hz like 40hz or less...the way I see it is there is a reason why they made that much adjustment...try it
It may be a little different than Aero would do it but I ain't getting any comebacks and if he was here with me when I was doing it he would be saying OH YEAH good enuff
And if needed don't forget to add the beef in and grind it where it's undetectable

[aametalmaster]

I do about a dozen Briggs a year and just use my mig and 4043...Bob

[Bodybagger]

I use a 1/4" carbide burr in a pneumatic die grinder with rear exhaust (front exhaust will contaminate the weld area with air tool oil). I hold it at a 45° angle with the surface to be welded, so it cuts a 90° groove into the aluminum. I precisely cut to a depth that leaves about 40 thousandths gap, which removes all traces of old material and contamination. The carbide burr leaves a cut that is incredibly smooth and clean.

I use 4043 filler and traditional sine-wave AC (50/50). On applications like this, zirconiated tungsten really shines. It doesn't encourage the sputtering that other tungstens do.

Motor oil is designed to resist extremely high temperatures before cooking off. It is darn had to get out and I swear traces linger even after heating to the melting point! Brushing smears it in... grind it out with a clean cutting carbide bit. That's probably the best you can do without an ultrasonic cleaner.

[FusionKing]

Yea I do that (spoolgun) on some castings from time to time esp. ones that have a bunch of grass imbeded in them like aluminum mower decks etc.
Spoolguns overcome nasty junk like none other IMO.
I've welded junk with a spoolgun that was so nasty you would not have believed you could'a welded it. Just scratch what you can and bevel if possible and fire away
Only problem is spoolguns happen so fast you need to bid those jobs
I used to have to fire up the Bobcat and run the spoolgun thru the WC-115a and it done a fine job. But then I bought my 350-P and hooked my 30-A to that and OMG!!! I brought in that "needle like" precision like you have on a normal steel mig only on thinner aluminum but yet still kept all the good spoolgun qualities. Not to mention it transformed it into a fire breathing dragon on the other end of the spectrum. My only problem is I am so set in my ways that I still go to the tig first.
AAMetalmaster I see your point too as well as Aero's..use what you know best and use it to the best of your ability...you bet'cha!!

[fun4now]

i was at 80 h and 45% bal. 4043 filler .
i cant wait to get the other one to play with. should be fun.

[fun4now]

no spool gun option.
just TIG and O/A.
i'll try softening up the arc and see where that gets me.
thanks for all the advice guys. i'll let ya know how the next one comes out.

[HMW]

Somebody mentioned the carbide burr and I have had great luck with that too. That and the stainless steel wire wheel on the grinder. Ive used a grinding disk before and wished i hadnt...live and learn

[59halfstep]

James,
Tig works OK, torch works a bit better due to the flux, but I usually use the Tig technology.
-Aaron

Aerometalworker - you mention torch. What would your recommendations for rod/flux for torch attempt? Thanks

Charlie

[Aerometalworker]

Aerometalworker - you mention torch. What would your recommendations for rod/flux for torch attempt? Thanks

Charlie

Charlie,
Same filler as for Tig, in this case 4043, and for flux I would use either the Tin Man or Allstate brand aluminum welding fluxes.
-Aaron

[59halfstep]

Thank you Aaron.

Charlie

[TIG332]

Engine case

Clean the aluminum with alcohol or acetone,use a carbide burr to vee out the crack, use a small dia tungsten to cook out the oil that is impregnated in the case,make sure that you stop drill the ends of the cracks.Do not add any filler rod until the aluminum becomes shiny from your cleanup passes with the small dia tungsten probably 1/16th.Use only a stainless steel brush that is designated for aluminm only.Die grind out contaminated material until no black stuff is present.When the aluminum does'nt show any signs of black residue you are ready to weld it.The 1/16 tungsten may start to wiggle during your clean up passes due to the heat on it, if this happens and you have a square wave machine turn your AC balance dial to the more penetration side.You can also get more heat out of your small tungsten by switching to a 75% AR 25% HE, or a 75%He 25% Ar. The reason I recommend a small tungsten during the cleanup passes is because when you use a tungsten too large for the amount of current that you are passing through it you can get contamination.A 3/32 tungsten should do the trick for you when it comes time to weld, I would use a 4043 rod maybe 1/16th for the first pass then fill it in with 3/32.I hope this helps you.