How do I weld up a sump without making it look like crap?

[RAd28]

Hi all,

Been toying around the last few days practicing welding on a spare sump i've got, so far i've just cut slots in it with a wafer thing disc, then proceeded to weld them up, I've tried MIG and OXY with mixed results, the MIG gave me nicer welds on the straights, but I can see i'm gonna have issues on the corners etc. the Oxy makes it easy to seal up in all areas, but i can't get it to look neat (MIG spots are giving me grief). So I figured MIG up as much as I can, then OXY the trouble spots...I thought all was going well, so I got some thin scrap sheet metal and proceeded to practice some more... it was here that i realised how much trouble i'm in for. It seems that the cutting and welding up an old sump didn't give me any introduction to shrinkage/warpage probably because of the shape. where as flat scrap warped like the minds of a doped up hippy...

So basically, I need advice mainly on how to reduce shrinkage... I've got the MIG set on the lowest voltage setting. and i'm struggling to get travel speed fast enough to keep the heat out. I found that I could manage a decent run on the scap sheet, then I found that after an inch or two it would just start crackling (one website described it as a machine gun) but I've got no idea why...

Anyone able to offer any advice? Happy to hear all suggestions...

[Justo]

I have only ever seen 1 sump being welded before so i'm not an expert by any means but heres how I saw it done. it was being reduced in depth and was form a holden 202.

The welder welded a few tacks around at the corners with a MIG doing opisite corners and waiting for a few seconds between each weld till it cooled down a bit. then he did a tack in the centre of the straight sections and let it cool between tacks. once all the tacks were done he did very small sections at a time (about in inch) on opposite sides and letting it cool between welds.

It looked good in the end but he did need to use a hammer near the end to make sure everything lined up as there was some distortion. he used a blowtorch (light blue flame) on it in the end but I'm not sure why maybe to check that it wouldn't warp and break the weld.

[Tweak]

Tig it. Much neater weld and its more controlled. But the factor is the heat.........
Seems your in abit of a hard spot. May be easyer to get a intire new sump made up out of alloy

[RAd28]

Tig it. Much neater weld and its more controlled. But the factor is the heat.........
Seems your in abit of a hard spot. May be easyer to get a intire new sump made up out of alloy

Basically, my options are:

1) don't modify the sump (and risk poor oil supply)
2) modify the sump my self, using the tools I have (MIG & OXY)

I figure I have time and patience on my side, and If i make a cock up of a sump, another one isn't gonna cost the earth...

[takai]

Tack it all around, then (seeing as your welder cant really do thin sheet well) mig it up in short bursts on opposing sides about an inch at a time.

[legend]

x2 like Takai suggested thats how i would do it

[RAd28]

alright.. sounds like a plan, I'll give that another shot tomorrow night... Any tips on how to make the stop/starts less obvious?

[takai]

Linish it.
Will help with seeing where you have missed bits on a leakdown test

[matty12]

thin stuff you will have to pulse it when using the mig..When doing sheet metal i do a little burn just to the point where it starts to get too much heat in it then stop.Wait until it cools so the bright orange goes away then go again.

Oxy will come down to technique so travel speed and filler speed etc.

[skiddz]

why do you care what it looks like? surely it couldnt look any worse than owens manifold welded with bird poo

[oldeskewltoy]

to combat the heat/warpage... find an old bare block, bolt the pan down when you do the work... it might just keep the warping to a minimum

[af300e]

to combat the heat/warpage... find an old bare block, bolt the pan down when you do the work... it might just keep the warping to a minimum

Definitely do that.

I built a bigger sump with gates for a rwd 3sgte and used the gen 3 alloy sump instead of an engine block as a heatsink/die.
The tin sumps are super susceptible to warping during welding.

Another way to help prevent warping is to ensure that the two pieces you are joining are actually butting together before the weld. If you are filling cuts then the weld shrinks as it cools and pulls the whole thing out to shit. Butting the panels together and using as low a current as possible means that there is less chance of it shrinking.

[RA23]

Pulsing works well with a MIG on thin sheet. Requires some practice though. Try on some scrap first. About 1 second on, 1 second off for a start.
Also can you go down in wire diameter?
What can also help to get rid of the heat quick is placing a few wet rags around the weld.

[manny]

You want to use the stitch MIG welding technique
Have a read of this info and watch the video
MIG Stitch Welding

[timbosaurus]

Hi Rad, a couple of things to insure are:

Complete cleanliness. While this also affects weld strength, it is most important for a consistant weld. Anything but beautiful clean steel could be the cause of that spluttering you're having. You are using sheilding gas?

Tacks. Some people say to tack every three inches, but i usualy tack every inch. Just a small tack that won't get in the way of the final pass.

I'll be surprised if your welder cant weld thin metal. Maybe the voltage and wire speed is that low that you have to travel too slow and are heating/warping too much? While practising, up the voltage and wire settings (till you can pass quickly without blowing holes), increase your torch travel and see how it goes.

For a sump, I would actually prefer oxy. I think it is perfect for that! Tack every inch, make sure the metal meets perfectly everywhere, and you shouldn't even need filler rod. Oxy does put in a lot of heat, but since you can get inside the sump to smooth it out, it shouldn't be a problem.