Cleaning an ally oil pan for repair

[4sfed]

Excelllent idea and so obvious. I've got one on the stand ten feet away.

I am clamping it to the steel benchtop and the normalizng took some of the curve out. The cracks look just the same after stop drilling. If I weld one side they merely migrate to the other side.
It may well be time to cut it out and patch it....

Since this is a sheet metal pan, it could be from one of two common structural alloys that are crack sensitive when welded autogenously (i.e., without adding filler metal) . . . AA6061 or AA5052. You must dilute the puddle with the correct filler . . . for AA5052, use 5356, and for AA6061 you can use 4043 or 5356. Even then, if you leave a crater at the end of a bead it may crack. Try a larger stop drill . . . 3/16 . . . which will require you to add extra filler at the end of the bead. Also, drilling a little beyond the visible end of the crack may help as the full extent of the crack may not be visible to the naked eye.

Jim

[GT6Steve]

Thanx Jim,

I was using a small stop drill and filling with 4043 rod.

I'm wondering if my 3/32 rod and #7 cup are too big for this job. Thinking about the HAZ. Material seems to be about .100 thick.

I made a big effort this morning to keep heat as low as possible. 135 Amps is the max on my pedal. Which sometimes seems right then as it gets hot it goes to **** cuz I'm not yet smart enough to modulate it correctly.

Getting better though, I'm now remembering(mostly) to maintain post flow and I can testify as to the mess it makes when you forget to turn the gas on

I'm still hopeful and encouraged. Appreciate the time you experienced folk waste with these repetitive questions from every noobie...

[GT6Steve]

WooHoo....

First stack of dimes. Crappy at either end but looked good in the middle!

Using a 3/32 stop drill and every effort to keep heat out now.

This'll be a $5000 oil pan by the time I'm done and half of that will be filler rod and sanding discs

[mastiffs]

i have done some oil pans. i agree with clean clean and acid tone and carbide bits ,alot of time i found even after all the cleaning,when you weld you have dirt rise up .i usally use a stainless wire wheel and dremel .pre heating helps to prevent more cracks .if i have a real broblem i have even put them in the oven (dont tell wife). when im done i ether cover it with lether or put it back in the oven to cool slow.. nothing like hearing that crack/pop when you think your finished .also if you have to shape something after if you dip your carbides in parifen wax the aluminum wont clog them as fast

[captkipp]

Thanx Jim,

I was using a small stop drill and filling with 4043 rod.

I'm wondering if my 3/32 rod and #7 cup are too big for this job. Thinking about the HAZ. Material seems to be about .100 thick.

I made a big effort this morning to keep heat as low as possible. 135 Amps is the max on my pedal. Which sometimes seems right then as it gets hot it goes to **** cuz I'm not yet smart enough to modulate it correctly.

Getting better though, I'm now remembering(mostly) to maintain post flow and I can testify as to the mess it makes when you forget to turn the gas on

I'm still hopeful and encouraged. Appreciate the time you experienced folk waste with these repetitive questions from every noobie...

GT6:

It's also quite possible here, and I hate to say this, that the heat isn't high enough to get good penetration. And this can cause the crack to remanifest itself almost immediately. Is this a cast aluminum pan? or is it made from die formed plate?

Cast requires a bunch of heat to start, but you have to modulate the amperage as you continue the weld. Otherwise the retained heat in the base metal will continue to escalate and can actually blow the base metal away.
I suspect that the crack is in cast aluminum as 6061 is a structural alloy and although possible, 5052 is a pretty soft alloy. I've built a ton of fuel tanks for the boat and marine industry from 5052 plate and repaired a bunch of them as well. Generally 5052 doesn't 'crack' like your describing. But cast aluminum will. 5052 will crack along the weld seam if the penetration isn't good. It also melts together real well and I use 4043 wire on this alloy, but according to the weld charts 5356 wire will work. 5356 wire and some cast alloys don't get along well. Neither does 5356 wire and 6061 base metal as the metallugical composition of the resultant puddle and weld...well putting it simply, ALLOWS it to crack.

If the heat is correct and the penetration is good, then this alloy may require a slow cooling process to avoid re-cracking. Cover it with some non- flammable blankets or slowly cool it in a hot oven by adjusting the heat down over a period of several hours. I doubt that you would have a commercial heat treating facility there, but if you do....

[captkipp]

GT6:

When you are done preping your crack prior to commencing the weld, what does it look like? Do you have an open root of about a 1/16 to 1/8 of an inch? Or is the base metal still very tight together along the crack line?

[Daniel]

I see you have a 30 amp spoolgun.The way I do it Is by preheating the crack region with a o/a torch to burn all the oil in there. if the material is only .100 thick I would weld right over the crack then I'll set my spoolgun with er4043 wire at 19 volts and around 400 wire speed it will have full penetration. Try a pass on the same thickness aluminium scrap and do a 3 inch pass and you'll see on the other side it will look like you welded it up on the inside as well. You have to be quick with the pass

You just have to make sure to burn all the oil out of the crack area before cleaning and grinding.

[GT6Steve]

Thanx guys,

Here's a link to some pics from awhile back.

http://www.sideways-technologies.co....?m-1259532468/

This is a sheetmetal pan and I believe it would've been 6061 T6 as we had a lot of that back then. About 1/8" thick.

Capt. The cracks are tiny and tight and show up after I grind the material smooth usually. I have grooved between the stop holes as you suggested and it doesn't seem to make a difference. Normalizing the alloy DOES seem to help.

I'm going back to work tomorrow so I'm going to show it to a really superb welder we have there. If I can get him to talk he'll know exactly what I'm doing wrong.

[SundownIII]

Captkipp,

Question.

I didn't understand your comment about why 5356 filler and 6061 base metal do not get along. Has that just been your experience or is this documented in some available reference.

The reason (amongst many) I ask is because I think if you check (pg 42, Miller Tig Handbook) the recommended filler for 6061T6 is 5356. Recommended filler for 6061T4 is 4043.

I also have done "a little" marine fabrication over the years. Your experience and mine must vary considerably. I use a lot more 5356 filler on the 6061 I use than I do 4043. If the part, rod holders, antenna mounts, etc., will be anodized post welding, 5356 is your only option. 4043 will turn black.

Are you, in fact, saying that Pipewelders has been "doing it wrong" for all this time?

What would bother me more about using 5356 for this application, would be the heat the material would be subjected to in this application (oil pan). 5356 doesn't like temps over 165 deg F.

[captkipp]

Sundown:

Just difference in my experience perhaps. I know a lot of welders that never change filler metal. Always use 5356. Cast, 6061, 5052, etc. There are some different thoughts on the subject. Heck the local supply house doesn't even carry stock on 4043. Obviously they know more than I do. I'll temper my input here and say it's my experience and not the normally accepted way to do it. At this point, I'd put the darn thing in the scrap bin, build a new one, weld it up with coat hanger wire and dip it in marine tex to fill the holes.