Modifying a structural oil pan

The 3400 has a cast aluminium pan with crossbolted mains going through it. This means (to me) its structural to the bottom end of the engine. 

As a last resort, i may have to notch it to clear the crossmember in the miata. 

Can i? Can it be tig welded afterwards? Am i borrowing trouble?

Id be taking about an inch out of the front edge of the sump.

Some pics would help.  Anything can be cut and TIG welded.  Go for it. 

Let me preface this by saying I'm a software guy, not an ME.  That said, as I understand it, if the aluminum was heat treated then welding it will remove that and it would need to be re-treated to get the strength back.  If it's a structural part of the block, then this might be significant.

Sacrifice the cross member, you'll be better off in the long run.....MIG'n plate/sheet trumps tig'n alumeuumm anything as far as what I've seen here lately..... 

I say go for it.  Just put back the same thickness of material in the areas that are modified.  Get sone one that has some experience with welding aluminum and I would not worry about it.  The only issue I would have is if it is cast alu and not sheet.  That may be an issue with respect to welding.  Better look in to that before you start cutting.  One of my guys at work is a licensed welder and he would know the answer.  I will ask him tomorrow and report back.

Plenty of cast aluminum has been professionally TIG welded for me with excellent results.  I bring my work to the chicken processing plant manufacturer.  Hey, it's Arkansas.  You can also buy guns at the coffee shop, but mostly black rifles.

The nelsons are modifying an l.s pan.   I see no difference.

I think it's ok to borrow trouble, as long as you put it back when you're done.

Cast aluminum definitely can be welded, my supercharger's intercooler housing is a welded set of castings from Pettit Racing:

Id have to farm this out to my localmachine shop. I can barely weld steel....

Im going to tuck this option back for after i get home. Hopefully it will not be needed

If you think of the typical design of an oil pan, they are not that strong. If you're notching it, you may actually be making it stronger in several areas. You could do what you want to do and test it pretty easily by twisting it with some rig, or just your hands. I'll bet the oil pan cast aluminum is not heat treated.

Welding aluminum is no big deal, but welding oil soaked aluminum is about as miserable as welding can get. If you can start out with a brand new pan you will have much better results for both strength and leakage.

I would be aware that depending on how you notch the pan, you may end up creating a second sump that will "collect" a certain amount of oil before it overflows into the main sump.  Might be worth adding a second drain.

Yeah... pics would help a lot here.

EastCoastMojo said:

I think it's ok to borrow trouble, as long as you put it back when you're done.

And make sure to ask first, otherwise it is stealing,

Could you notch the crossmember instead? The advantage there is that if you need to replace the engine, you don't need to worry about modifying the new oil pan or moving the oil pan over from the old engine. Maybe you could make a tubular crossmember that clears.

Is this the pan you are up against?

oldopelguy said:

Welding aluminum is no big deal, but welding oil soaked aluminum is about as miserable as welding can get. If you can start out with a brand new pan you will have much better results for both strength and leakage.

If you can't go new (or even if you do go new), try to find someone with an industrial oven that can bake it for several hours to try to remove as much of the oil as possible. 

When I worked for a company that instrumented engine components, the first step was always to bake the parts (new or used) to get rid of any oils in the metal so adhesives would bond reliably.

NOHOME said:

Is this the pan you are up against?

 

yest it is!!!! i was actually trying to figure out how to hotlink again to show a similar picture. 

whats in my head is to make it look like a standard SBC oil pan: flat and thin in the front, deep sump about halfway back to the end of the pan. i found a single picture of a guy that did it for swapping into a second gen s10. but again, cant remember how to hotlink....

jstand said:

oldopelguy said:

Welding aluminum is no big deal, but welding oil soaked aluminum is about as miserable as welding can get. If you can start out with a brand new pan you will have much better results for both strength and leakage.

 

If you can't go new (or even if you do go new), try to find someone with an industrial oven that can bake it for several hours to try to remove as much of the oil as possible. 

When I worked for a company that instrumented engine components, the first step was always to bake the parts (new or used) to get rid of any oils in the metal so adhesives would bond reliably.

would mapp gas or a propane tprch be suffiecient to burn it all out? 

jstand said:

oldopelguy said:

Welding aluminum is no big deal, but welding oil soaked aluminum is about as miserable as welding can get. If you can start out with a brand new pan you will have much better results for both strength and leakage.

 

If you can't go new (or even if you do go new), try to find someone with an industrial oven that can bake it for several hours to try to remove as much of the oil as possible. 

When I worked for a company that instrumented engine components, the first step was always to bake the parts (new or used) to get rid of any oils in the metal so adhesives would bond reliably.

Indeed my materials guy suggested baking it at low temperatures, he said 400F for four hours, then weld. It worked for my bellhousing.

In reply to Dusterbd13 :

too hot.

CL electric oven search?  Seems like if a person were to clean it manually as much has he could, he could then bake it at really low temps and stair step it up to 400 to slowly de-fume the thing.  Like start at ~150 for an hour, then ~250 for an hour, etc.

Then there's the whole getting-the-work-done aspect of this.  

Dusterbd13 said:

How much oil capacity does that lose?  You're not needing that much cut back are you?

Unknown about oil capacity loss. And id honestly only need about 1/2 that cut back, tops. Probably only an inch or so, and tgats only if my next idea on making space fails as well.

The current pan is definitely much larger than the 4.5 quart oil change spec, but im not sure by how much internally.