Aluminum outboard skeg repair (bigger one this time... with He mix)

[undercut]

The customer e-mailed me some pictures of the finished result. He seemed pretty proud, and I would say for good reason! Looks like he did a very good job getting it all back together.

Here is the weld-repaired lower unit after paint:
Attachment 6732

And here is the rebuilt, completely assembled outboard motor (a 1979 Chrysler) that the lower unit got installed into:
Attachment 6731

Oh yeah. Very nice. Can't tell anything was done. Looks stock! Very nice feeling, putting in the effort, getting a happy customer and seeing such nice results! Think I saw Rod post somewhere that he built something to circulate water to avoid heating the seals. Doesn't seem to be in this thread so I'll hunt around for it. Thanks for sharing this repair with us.

[Rodsmachineshop]

i used some old fittings off some marine gear oil hand pumps i had for since seams the plastic pumps don't hold up good so i save the hoses and fill fittings , then used a 5 gallon bucket and swamp cooler pump to pump distilled water through the unit to keep cool just used cheap clear hose i got from ace hardware . after done i use a old quart gear lube bottle with the pointed fill tip and rinse out with mineral spirit's to push all the remaining water and moisture out . use mineral oil since softens the seals in unit back to soft if they are hard ,

[jakeru]

Oh yeah. Very nice. Can't tell anything was done. Looks stock!

Thanks, yeah I think he did a really good job of blending the texture at the end there and making it look as if it were never repaired in the first place.

i used some old fittings off some marine gear oil hand pumps i had for since seams the plastic pumps don't hold up good so i save the hoses and fill fittings , then used a 5 gallon bucket and swamp cooler pump to pump distilled water through the unit to keep cool just used cheap clear hose i got from ace hardware . after done i use a old quart gear lube bottle with the pointed fill tip and rinse out with mineral spirit's to push all the remaining water and moisture out . use mineral oil since softens the seals in unit back to soft if they are hard ,

That sounds like a pretty interesting method there, Rod. Are you circulating your water coolant through the lower unit somehow (through the passageways that normally have gear oil in it, somehow; is that what you're saying?) This would require disassembling the lower unit... correct?

My impression of the usual cooling passageways in an outboard designed to cool the engine above the water is that they do not cool the lower unit. If I'm wrong on that, please let me know.

i looked at your skeg repair when you posted it the first time; those welds are way to cold. just because you filled a gap, ground it down, got it painted and it looks nice, does not mean it's strong. the skeg repair would only play to a friendly audience, like the one on this board.

that said, your presentation of procedures used during the process of the repair is impressive.

Usually when someone says a weld "looks cold", I believe they are referring to the arc temperature used to perform the weld as being too cold (such as by not being set with adequate amps.) In the case of this skeg repair, with the max my machine can put out (nearly 200 amps), 80% EN AC Balance, and using a helium mix (and a pretty much instant puddle as soon as the arc was lit, even with cool-to-the touch workpiece), I assure you that the arc temperature was not "too cold."

So, I think you might be actually talking about the workpiece being too cold, such as by not allowing enough heat to soak into it, or not pre-heating it enough. As I discussed pretty extensively in my original posts, that was my goal, in order to prevent the customer from having to replace the nearby seal, and possibly also from needing to completely disassemble and rebuild the entire lower unit.

Sometimes, even when a weld isn't as good as it *possibly* can be, it can still be "good enough." As long as I this skeg isn't abused, I do believe it will hold just fine. I know that I penetrated it fully (by puddling *before* adding filler rod), and I also know that I selected a filler rod alloy that would give a pretty high welded strength (and ductility) in the weld deposit. Finally, I ground the contour to eliminate any stress risers. That's about as good as can be done, under the constraints of this particular job, at least to my knowledge. But if you are aware of a technique that I could have used to do it better, please fill me in on it.

[Rodsmachineshop]

A lower unit has to plugs to fill, you fill a lower backwards . you fill from bottom plug till gear lube comes out of upper plug , when coming out of top plug hole you remove lower fill tube and put lower plug back in then top plug. i put the fill coolant hose distilled water to lower hole then have return hose going to bucket , after done welding i back wash with mineral spirits to push any moisture out . oh the pump thing in the video is expensive i made my own out of a pump bug sprayer cost like 18 bucks to make ..also made brake pressure bleeder with the same sprayer . made the master cylinder plate out of some flat plate steel and got a flat piece of rubber from the hardware store to seal it. posted some pics of bleeder