[Spokerider]

Guys,
I need to mod an engine oil pan. I need to relocate the drain bung, and mod the pan volume for axle clearance issues. I'll be adding "volume" to another location of the pan to make up for removing clearance volume.

Do I weld with ER70S2 or 309 rod?

Will the 309 rod help mitigate porosity? Flow better than ER70S2?
Will the weld be susceptible to cracking due to reduced ferrite levels? Heat cycling cracking?

Never tig welded an oil pan before. If I have issues, it'll be related to pin holes and porosity.

Read that I need to "back step" the welds when stating a new weld bead from the one that was just laid down.......I'll need to research this technique more.

Thanks.

[MinnesotaDave]

If it's just a steel pan, I'd use 70s-2 like usual.

I've moved bungs and added the big oil returns for braided line with the regular rods - no problems noted.

[Poland308]

The hardest part about old steel oil pans is the saturation from the oil. Even if there soaked in solvent, you will want to use a pre heat up to about 300f or a little higher at least one time to help cook out the oil from the metal. You can let it cool before you weld on it, but even then you will be cleaning your tungsten a lot. I’ve used both 309 and 70S2. Either will likely be fine. You might also consider using 70S6 it might help clean things up a bit.

[Spokerider]

Thanks for the advice guys. It helps instill confidence......

What about using brazing rod? Is that an option? I see one thread where a guy brazed a modded pan together.

I have 309, 312, ERS70s2 and silicone brazing rod. Don't have any 70s6 but could prolly buy some.

[Oscar]

The hardest part about old steel oil pans is the saturation from the oil. Even if there soaked in solvent, you will want to use a pre heat up to about 300f or a little higher at least one time to help cook out the oil from the metal. You can let it cool before you weld on it, but even then you will be cleaning your tungsten a lot. I’ve used both 309 and 70S2. Either will likely be fine. You might also consider using 70S6 it might help clean things up a bit.

Its a sound idea to use preheat, but then again [watching a lot of youtube videos] I see that there is almost always something boiling off the steel (from the small amounts of smoke seen rising), and you can still get sound welds.

[noddybrian]

I've done plenty of oil pans both repairing damage & adding or moving fittings for turbo returns etc & have always brazed with oxy / acetylene - most pans were put together that way for years - not sure now as I don't work on modern stuff much - never had a problem this way - I never feel Tig is a good process when the metal is old / rusty or oil soaked as I always end up fighting porosity & usually have to stop many times to clean the tungsten of crap that spat out of the puddle - some folks seem to like Tig & try to use it for everything where I try to use the method that works well with least fuss or fastest - so depending on the job I would go fo Mig 1st - stick 2nd - oxy 3rd Tig 4th unless it's aluminum !

[Poland308]

The pre heat recommendation has more to do with the fact that most oils are hydrocarbons. They can contribute to hydrogen precipitation. Thus causing brittle welds prone to cracks. Not good on a high end oil pan.

[Vicoor]

ER70 S2 will work just fine, 309 would work too. I've never seen issues with carbon steel soaking up contaminants. That's usually something you find in cast parts. But you will need to clean and deburr it well. All the paint and coatings should be removed at least an inch from the welds.

[cj737]

I've never seen issues with carbon steel soaking up contaminants. That's usually something you find in cast parts.

You are aware carbon steel is porous, right? An oil pan will soak up oil, road grime and other “weld contaminating” impurities irrespective of it being cast, forged, billet or hydro formed. Cleaning the carbon steel is easier than a cst aluminum pan by miles, that I agree with. But they both soak it up.

[MinnesotaDave]

I've never seen issues with carbon steel soaking up contaminants. That's usually something you find in cast parts.

You are aware carbon steel is porous, right? An oil pan will soak up oil, road grime and other “weld contaminating” impurities irrespective of it being cast, forged, billet or hydro formed. Cleaning the carbon steel is easier than a cst aluminum pan by miles, that I agree with. But they both soak it up.

Respectfully, I disagree. If steel was porous, the oil would leak through to the other side and out onto the ground.

[tungstendipper]

I've never seen issues with carbon steel soaking up contaminants. That's usually something you find in cast parts.

You are aware carbon steel is porous, right? An oil pan will soak up oil, road grime and other “weld contaminating” impurities irrespective of it being cast, forged, billet or hydro formed. Cleaning the carbon steel is easier than a cst aluminum pan by miles, that I agree with. But they both soak it up.

Respectfully, I disagree. If steel was porous, the oil would leak through to the other side and out onto the ground.

So if that's true, why don't cast pans leak?

[cj737]

Perhaps “porous” isn’t the correct terminology. And I certainly don’t intend to imply that it is porous enough to leak. Carbon steel absorbs oil due to grain structure (porous as I put it). Cutting fluid impregnates steel to open the grain to aid in cutting when machining. Cast aluminum is riddled with air bubbles, which causes porosity. Some cast pans will weep oil, but mostly due to poor quality casting.

We all know how absorbent cast iron is. Cast steel is as well. If you disagree, look under any truck or vehicle that has seen years of use and try to clean the steering knuckles, control arms, etc. That road grime is embedded in the steel.

So I’ll restate what I said, with carbon steel being “absorbent” and needing to be cleaned prior to welding (in the case of an oil pan).

An aside, most modern oil pans are aluminum, not steel to reduce the condensation and moisture absorption into the oil. Also, aluminum dissipates heat better than a steel pan will by extracting the heat from the engine oil. Heat and moisture causes heavy frothing in the oil, which is very detrimental to oil lubricity.

[tungstendipper]

My Ford's F 150 oil pan is plastic.

[cj737]

My Ford's F 150 oil pan is plastic.

Gotta be super talented to TIG weld that! But I bet you’re up to that challenge