Advice on an aluminum oil pan repair.

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Hi Fellas (and ladies lurking),I am working on an aluminum oil pan off of a Ford something or other. It has a crack and I'm in the process of welding it up.  Clients bring me their aluminum projects and I have no difficulty repair welding them, be that a bicycle frame, rim, a tranny case, engine block, etc.This oil pan that is giving me problems because the crack has returned.  The method I use for oil pans in general is to prepare the joint by drilling out the ends of the crack and then grinding out the crack.  I use wet rags to surround the weld zone so it can absorb the heat and minimize it spreading to the rest of the casting.  I do this in lieu of heating it in some type of oven which I don't have.I start running small beads from the hole I drilled in for no more than three or four seconds at a time and then let it cool down until I can place my bare hand on it and begin the puddle again.  I treat it the way I would weld cast iron.  It is a method taught to me in a posting I made last year when fixing an old cast iron sink from the depression era by one of the welders on the board and I'm sorry I can't remember his name offhand.I do this until the crack is filled up and I have never had any problems before.  This pan however is particularly brittle and when I was finishing the last of the weld, a crack formed alongside the weld.  I drilled and ground it out again and  welded it again this time reducing the time to two seconds or so at a time.The crack returned, this time back where the original crack was.  I have drilled it and ground it out again but this time before starting on it I wanted to tap the collective brain of my welding brothers (and lurking sisters) to see if anyone has any thoughts as to how to proceed with this repair.I did not want to weld the inside of the pan so as to not have to put more heat into it so the crack is not sealed inside, only outside.This particular pan has a pot metal feel to it in that it is thin has an almost "tinny" lfeel to it.  It is not a stout casting like an engine block or tranny case.  However unlike pot metal, the puddle forms and runs like aluminum and not pot metal which more or less fizzles away when you put a tig torch to it.Anyone have any ideas?  Do I heat the whole pan and keep it hot while I weld on it?  I let the client know that I was unable to repair the crack but that I could try again using a different technique to see if it could be done.  He said that it was a hard to find pan and to try again.What do you all think?Thanks,Tony
Reply:I am only speaking from what I have read, and i hesitate to say anything because I am only a student, and not even qualified to be an apprentice, but if its an oil pan, and it has been exposed to temperature, maybe its more brittle because of this.  In which case (again from what I have studied) maybe the weld is cooling too fast and producing the crack.  Have you tried post heat, to keep it from cooling too fast, which might be happening because of the wet rags?Lincoln Electric, Power MIG 256Hypertherm Powermax 45 Miller Dynasty 280DXSmith O/A torchGenesis of a welding table
Reply:Did you try using 4043 filler rod. Could also try some zinc/propane rod??
Reply:I'd heat the whole pan and then go at it with the welder until the crack is filled and let cool on its own.Some cast aluminum just simply won't take a weld. Its pretty rare but I have seen it a couple times.
Reply:I have run into the same problem on a few occasions.  What I determined is the part was not an aluminum Casting, but a die casting.Synchrowave 300   Old but reliable
Reply:therrera, With your experence Iam sure you have it really really clean? I have seen what you are talking about I have drilled a hole on each end of the crack,grind out the crack like you have and clean with stainless steel brush and clean with acetone..Heat the pan up either with a torch get it to around 350 deg.With what you are describing is the casting is so porus that its letting oil out of the crack and contamination..You are not able to see it very well but it is happening and not allowing the weld to sweat in properly.Just a cheap poor casting job I would weld the inside and get after the heat too!!Miller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:I would possibly weld it and then stick it in the oven or wrap it in a heat blanket. And let it slowly cool. Check out those durafix rods as well. They are brazzing rods. Go check out the videos, I've never used them but they look good in the videos, they are expensive as h**l though. Good luck to you
Reply:I think it's new pan time.  Aluminum thats exposed to oil, over time absorbs some and you can't remove it so whatever you do, the weld won't seal.  Some things can be fixed, some things aren't worth the trouble.  This is one...Scrap it and get another.
Reply:Hi All,thanks for the suggestions.  I don't have access to an oven other than my kitchen stove and I would stink up the house, not to mention soot up the stove if I tried to put it in there to get it to 350 degrees.I think I will put a torch on it and get it hot.  I will use the acetylene trick of coating some carbon on it by running a carbonizing flame over it and then heat it until the black soot disappears.  That should get it  up to around 300 plus degrees.  I will then weld it in one shot and cover it with a heat blanket .I will weld it inside and out and see how it goes.I'll let  you guys know.Thanks,Tony
Reply:Are you sure it is not mag?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by shovelonAre you sure it is not mag?
Reply:I would say zinc/aluminum alloy..tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:Yes try the heat blanket, preheating is a good trick too. Everytime I weld cast I preheat the metal. As far as the oil goes I weld up broken motorcycle crankcases all the time, I use the torch to clean the metal(in my mind it burns the oil from the metals pores) I'm not sure if it actually does. But it seems to help clean so I get a good solid weld.
Reply:Hi All,thought I would reply before turning in.  I don't know that it is not aluminum.  I tend to doubt it could be magnesium only because I think that would imply a higher grade casting which this one is definitely not.  Also while I have never welded on magnesium, what I have read is that it gives off a colored arc when struck.  Also it reacts to vinegar and I will put a few drops on it tomorrow to see if it bubbles.That it has zinc alloyed to it, is definitely a possibility because it has a "pot metal" feel about it.  Overall I think it is a low grade, cheap casting.  I have welded for example on Mercedes or even Toyota pans and they are of a higher grade casting.  It is not porous like others I've welded on.I use a torch to burn out the oil also.  This I do for all oil area castings (oil pans, valve covers, etc.) and it definitely burns / boils out the oil.  I also run dry passes with the tig torch to help boil out the remaining oil and usually don't actually start welding on a part until four or five passes over it with the torch and a good wire brushing.  This helps to clean the metal prior to laying the rod down.This casting though is tricky so I will make one more effort to weld on it, heating it up and welding it in one shot, turning it over and welding on the inside all the while running a torch over it periodically so it doesn't cool down on me.Then I will cover it and see what happens.  if it works then I will use this technique for future such jobs, if not I will better know when to cut my losses and suggest the part be replaced.The only reason I am going to great lengths to repair it is because the client expressed that he has had a hard time locating another pan.I'll report on how it went with some pictures.  I also thought of using that aluminum solder type product and keep some handy, its called "Aladdin" and requires heating the part up to about 500 degrees so it can flow.  I was reluctant to do that as I felt it might lead to more cracks.Thanks,Tony
Reply:Could try to braze it with something like Sealcore? Sometimes brazing is less "violent" for the finicky metals.
Reply:grind out the crack .drill it at both ends . clean the metal with acetone.if you don't have acetone use denatured alcohol . then weld it all at once with 4043 rod . cover it with a heat resistant blanket & let it cool down on its own. works for me.....
Reply:Hi Tony..Maybe you can gather some info from this..http://weldingweb.com/vbb/showthread.php...hlight=oil+panHappy welding!...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Does the oil pan have a checkered or crosshatch pattern cast anywhere on it by any chance?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Hi all,it doesn't have an checkered pattern or any type of strengthening in the center of the pan, it is just plain flat.  I am going out in a few minutes and give it a shot.  A job walked in the door and delayed me.  Here goes.....
Reply:Originally Posted by therreraI use wet rags to surround the weld zone so it can absorb the heat and minimize it spreading to the rest of the casting.  I do this in lieu of heating it in some type of oven which I don't have.I start running small beads from the hole I drilled in for no more than three or four seconds at a time and then let it cool down until I can place my bare hand on it and begin the puddle again.
Reply:If all else fails, the owner of the pan might try epoxy. I'm not sure whether it will adhere to aluminum but it's worth a try.If he does go that way, he might first try cleaning/etching the crack area with sodium hydroxide (lye or oven cleaner) but must be careful in doing so because sodium hydroxide actually "eats" aluminum.Last edited by Kelvin; 12-31-2012 at 06:14 PM.
Reply:a gas bbq works fine as an oven.miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet
Reply:Originally Posted by KelvinIf all else fails, the owner of the pan might try epoxy. I'm not sure whether it will adhere to aluminum but it's worth a try.If he does go that way, he might first try cleaning/etching the crack area with sodium hydroxide (lye or oven cleaner) but must be careful in doing so because sodium hydroxide actually "eats" aluminum.
Reply:Hi everyone,Well I got the part welded out, heating the pan first to about 250 degrees (using a temp stik).  Then I welded first the inside, sealing it all up.  After that I flipped it over and clamped it down on my steel table  and reheated it to bring it back up to 250 degrees.  Then I welded the outside running a wide bead over the previous weld, post heated it and covered it with a flame resistant blanket and left it alone until it was all cooled down.I forgot to take a picture of the finished repair so only have pictures of the first stages.  You can see where I had ground down the previous repair, re-drilled  holes and ground out a groove for welding.I checked for leaks using gasoline that I poured into the bottom of the pan and checked periodically for seepage after it had cooled down.  I found that the crack had expanded on the ends of the welds about 1/4" so I re drilled new holes, ground out the crack and then welded those ends up, repeating the pre-heat and post heat.I found also that the puddle ran much smoother with the pan heated up.  Thanks for the advice and new procedure.  I think also that I will locate a used propane BBQ grill to use for an oven to preheat.Thanks,Tony Attached Images
Reply:Is that off of a masey ferguson tractor?I hate being bi-polar it's awsomeMy Heroes Have Always Been CowboysThe large flat surface is what was giving you the problems. To much shrinkage while cooling with nowhere for it to move (held in place by the large unheated area). In a case like that preheat is the only way to go.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:I don't know what vehicle the oil pan came off of, only that it was a Ford.  It had the Ford emblem in the casting.  A place that rebuilds engines brought it to me.It is a new client and so far they have brought me two projects within days of each other.  Another reason why I wanted to find the right solution for this repair.Thanks everyone for the help,Tony
Reply:FWIW, thats a permanent mold casting . . . the least expensive way to make high volume aluminum castings.  In the first photo you can see where the molten aluminum flowed into the surface cracks in the steel mold.Changing the composition of the weld pool with additional filler may also help.  Instead of grooving the crack, try cutting through the crack with a saw(zall) then bridging the two sides together with filler.Dynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:Hi 4sfed,using that procedure, would I still heat the pan prior to welding?  I chose to post heat in order to keep the metal at more or less the same temperature as I was afraid of further cracking if the part had different temperature zones.Thanks,tonyLast edited by therrera; 01-04-2013 at 03:52 AM.Reason: to clarify my question
Reply:Preheating aluminum almost always helps.  The reason aluminum cracks is because it has little ductility or strength at higher temperatures and a high expansion rate.  Most alloys begin to melt above around 1000 to 1100 degrees F, but some are not fully liquid until above 1200 degrees.  If your part is not preheated, there is a large temperature difference between the weld pool and the part.  From the point the pool begins to solidify, a tensile stress develops in the joint because the welded area has expanded more than the rest of the part and shrinks as it cools.  If the stress builds before the joint can regain sufficient strength (strength and ductility are dependant on temperature) the weld will crack.  Some alloys are more sensitive than others . . . higher strength or more ductile at high temperature.  That's where filler choice can help.  And the joint alloy is some combination of the filler and part, so extra dilution of the pool by filler may help.  Preheating helps because it causes some expansion in the part prior to welding, so the joint shrinks less before it matches the temperature of the part.Dynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A