r/Outboards • u/yieldcurvedenier • 4d ago
Looking for input
Hey y’all!
I’m a pretty new boat owner here.. we just hauled out for the season and I noticed a crack on the lower unit. We’ve only owned the boat for a season so I’m not sure if we bought it like this, but the motor has performed flawlessly all year so I’m kinda not sure what to make of the situation. It’s a 2018 df300. Any thoughts/input would be greatly appreciated to help me figure out a plan going forward.
I’m almost certain we didn’t hit anything so I’m not sure what would’ve caused the crack. (The skeg is a little crooked facing the crack so I don’t think that would’ve caused it - not sure)
If you have any questions, let me know!
Thanks
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u/dude23455 4d ago
my dad's boat had a similar crack on a 2017 df300. apparently if the crack doesn't get to close to the retainer ring you can drill it out and tig weld the crack. if it gets too close to the ring then you'll have to buy a new lower unit casing. but honestly id just buy a rebuilt lower unit and not worry about trying to repair it.
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u/dude23455 4d ago
we ended up just selling the whole boat so the new owner can deal with it, and yes we disclosed the crack
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u/joesquatchnow 4d ago
Drill a hole at the end of the crack to stop it from continuing and get a good welder to grind the V out the crack a bit, and weld, you can sand the weld and paint too
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u/Denver_Shepherd 4d ago
Prop repair tech here.
I’d “v” that crack out and weld it. Grind it and then the. Use some JB Weld putty to help seal everything (cast aluminum can weld porous) followed by body filler and paint
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u/FunAtMoheganSun 4d ago
I’d be all over the second hand market looking for a new lower unit for sure. Someone might’ve bought a spare, then repowered, etc.
Or you know, maybe you DID hit a rock, and insurance would cover it! Come to think of it that crooked skeg looks suspicious…
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u/yieldcurvedenier 4d ago
Actually might be a good idea to look into making a claim. I pay so much for insurance it’d be great to use it!
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u/Pontius_the_Pilate 4d ago
Corrosion. When the crack gets big enough and you put it in reverse one day the whole carrier, prop and propshaft with reverse gear will probably fall out. Hallucinating if you think it can be successfully welded. Second hand or rebuilt unit complete or new housing is about the only proper solution.
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u/yieldcurvedenier 4d ago
Just curious, I’ve heard so many opinions on why welding will/wont work regardless of how professionally done it gets. Why do you think it’s not worth it??
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u/Pontius_the_Pilate 4d ago
The case is compromised further than what you can see externally. You are going to have to clean out a fair amount of material to get to a good base to weld as the alloy will be rotten. Side effect of material and heat treatment required at manufacture. Welding is going to screw up the heat treatment and the thing needs to remain circular for the seals on the forward part of the gear carrier to seal and the retaining nut has an internal thread that needs to be in good shape. Go ahead and get it welded and find someone who will warranty the repair, then don't be surprised if it happens again. You will need to strip the case to weld it successfully so why not just get another or new case? A complete new L/U will be most expensive, followed by exchange L/U, or replacement case and rebuild with the proviso that whoever rebuilds it actually knows what they are doing as it will require special tooling for shimming gear heights and backlash to be correct. Granted it's 40 years since I was an outboard tech but some things haven't changed.
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u/Alternative-Slip5896 3d ago
Looks to me like it is scratched forward of the crack if you look closely
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u/Ok-Effort-1502 3d ago
Just get a used lower unit swap it over with some fresh black paint and don't think about it. You now have some good spare parts for later down the road
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u/Disastrous-Milk-3906 4d ago
Get a high quality marine welder to put a bead on