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Painting an Outboard Lower Unit

In this video I weld, straighten bog and paint the lower unit from my Johnson 30HP outboard.

Painting an Outboard Lower Unit – Video Transcript

Hey there, Dangar Stu here. Today's video is about painting an outboard lower unit and it's proudly sponsored by MarineEngine.com.

Last time we saw this gear box I was sending it off to be sandblasted I actually think it was blasted with macadamia nut shells, but you know the idea is the same. We'll have a look now at how it came out after the blasting. Blasting is great because it gets really clean, and where there are soft spots, metal gets eaten away that's just, you know par for the course. But I always see as a good thing. Because you get to see where there is good metal and where there was bad metal, and you can do something about it or you can decide that it's a write-off. So, whatever.

Look, and I'll show you what it's like. This is it now, and you can see that there's a couple of really reasonably big pits in it, They're not all the way through, and I think this part of the casing is actually quite thick. So, I'm not worried about it at all. I think it's really interesting to see an old outboard like this and see how much this pitting is on the front edge. Here where the outboards getting hit by silt and rocks and everything and sand, as it's traveling through the water, and the water itself I guess. And then, on these trailing edges is actually still very smooth. Like here, it's almost perfect. So, maybe that says that a lot of this actually, isn't you know, sand corrosion. It actually is just straight abrasion.

So, what we're going to do, is we're going to start by doing a few things here. This leading edge is chipped away a bit. So, I'm actually going to try and TIG that. We'll do that first. We'll put a little bit of extra metal and just see if we can build that up enough that we can file it back. So, I think it's how we repair that. There is a few wavy bits like, you'll see here. So, I'm going to have a go at just hammering those flat, maybe leaving them. We'll see and then after that, this is the other side, it's probably even more pitted. I'm going to use an epoxy to try and fill all this once this epoxy will sand, it will prime, I will paint it and you'll see the finished product.

Okay, so first step is we'll go put it in the vise. And we'll just see if we can build this leading edge up a little bit with some filler metal. My plan here is to use a reasonably low current have the amp set low and just try and build metal up beyond the old curve it used to be, and then being aluminum, we should be able to file it back pretty easily. So, now the edges sort of built up like this bit of aluminum all around there was also a big divot here. So, I had a go at filling inside that and it actually went pretty well. I'm going to start by using a flat disk which is essentially a disk with all these little flaps of sandpaper on them on a grinder, will get the bulk off when we get close, I'll move to a hand file. It's going okay but there was a little bit of a low spot here so I'm just added a bit more filler metal so that went okay in the scheme of things we now have an edge that looks like that.

So, we've got back to not having that big chunk out of it and it's the top that still got a bit of pitting underneath. But, same as everywhere. So, we'll be doing the epoxying to fix that. Hopefully, what I'm going to do first though, is try and hammer out some of those sections that are a little bit bent and curved. When it comes to bending this I did a bit of research on whether the heat method or whether to do a cold method, and there hasn't been a clear answer in my mind. So, what I'm going to do is use this as an experiment. I'm going do some of the repair cold I'm going do some of it hot. Then I'm going to do some of it where I've heated it and then quickly dunked it in water, then hammered it. So, we'll try those three techniques see if there's any noticeable difference.

What I've done here is put a couple of steel blocks on top of the metal welding bench and clamped it down. You can see this, the section that's up, is probably the worst one. So, I might try this one cold, and we'll see how that goes. I'm expecting this to be quite loud, that sort of sharp metal on metal, so I'm just going put some earmuffs on for this. I think that's all I'm going to do, it's pretty close to flat now. That bent so easily that, you know, I think I'm just going to do this all cold. First hit you could feel it sort of bend, didn't feel like it's going to break. It's hard to describe, but it actually felt good. So, I'm just going to go along and do this whole edge just cold. Well that came out pretty well. You know it's not perfect.

You could spend hours with a straightedge, you know, trying to just get it spot-on. But I've got to say you're actually all here for a pretty momentous occasion. The first time that working on an outboard was easier than expected. That's a rare thing. What I'm going to do now is give it a bit of a clean from me handling it now, and then I'm going to mix up some epoxy and we're going to try and sort of put a coat on to skim in some of the pitting and clean that up a bit. So, just a clean cloth and some acetone will just give it a quick wipe over we're not speaking to Matthew who does the same blasting I was saying I had some two-part auto epoxy I was gonna use and he said no you're better off using sort of like a metal epoxy.

Now look I've actually got some of that, so this is the one I've had in the fridge for quite a while. I got to admit it's been in there poking about three years, so it's not new but I'm going give it a go. I think you need to consider this part of the project an experiment. Really, it's just a bit of fun to see how it turns out. Because of that I'm using things I've got lying around. If there is a better product, I'll let you know. Because it's worth using the right thing if you're intending to do it. And you know, get a long-lasting result. But in my case, I'm just going to use what I've got. Turns out what I do have is a good product to use. But ideally should be fresh this particular epoxy is one to one. So, you just pour it out of the tube in stripes of about the same length. I'm going make up a fair bit because we've got a fair bit of bonding to do unfortunately.

So, there we go a 50/50 mix. Well, at least close enough for late night television. The trick I think with these larger Divots, these larger sort of craters in Here, is to make sure that you don't trap air under the epoxy. So, you want to make sure you're really getting it down in there and you're not just creating a skin over an air bubble. What I'm going to use now is one of these things, sort of an applicator blade you get from auto parts stores. Really cheap, and the metal ones are quite good. Little bit harder on the tightly curved sections, but we've been going alright so far.

This is what it looks like now after a bit of a skim of the epoxy on that sections. Mostly done on this side, certainly the bad section of the front here. You could go nuts and fill all these little sections, but, we will be priming and sanding still too. So, I think I'm going to resist the urge to coat the whole gearbox in it. What I'm going do now is let this dry. just use up the last two it may as we use it all and once it dries I'll turn it over. I'll do the same thing on the other side and then we'll start sanding. The epoxy is all set. Now, I'll give you a look. I've had a little play at seeing how easy it is to sand, but it's quite a coating on all here. I probably could have skimmed it a little bit thinner.

But, keep in mind what I'm going to do now is get the bulk of it off with a power sander, and then I'm just going to get a piece of sandpaper like this, and just start finishing it up ready for painting I ended up doing quite a lot of sanding with the flat disc on the angle grinder. And it went pretty well. A flat disc is a very aggressive form of sanding. So, you got to be careful. But, you've got a lot of control when it comes to these contours. So, in that sense it was good because of flat disc is quite aggressive, it also let me take a bit of the aluminum away in places where I need to, round some edges all that kind of stuff. I then went on with a bit of 400 grit sandpaper and just hand sanded the whole thing, and I'll show you now, what it's looking like. So, what you end up with is this kind of thing where you're sanding till you can see bright metal again.

And the epoxy is only left in the low points. I don't want a buildup of epoxy. I don't want this sort of complete layer. So, I've got it right back so it's just all these little bits of pitting for the epoxy is left in. You'll see here in a few places I need to put more epoxy in, here and here. It hasn't quite filled the holes where I've sanded it there's still a little depression. If you were trying to get this to showroom condition, say a classic outboard. You're really looking to restore, you would just repeat the process. More epoxy on, let it sit for a few days, sand it back, rinse repeat. Keep doing that until you got the finish you're after. I really can't afford the time to do that. If I do that, it'll be 2 more days.

The weekend would be gone. Have to make a different video you know. That's life. I'm not too worried though, because it's going to be heaps better than it was. and if I wanted to turn it into a showroom condition gearbox or lower unit, I would actually need to put this epoxy over every square millimeter of it and sand it all multiple times. And it's just not worth it. So, if you're looking to get that effect, just takes time, the techniques shown are the same. Alright, what I'm going to do now is, I've got just a rag stuffed in the gearbox here. It's okay to give it a paint around here where we're pushing the bearing carrier in I've got all our plugs in, so dust and paint and whatever can't get in there. I'm then going to tape up the top here a little bit. I've got a rag on top of that oil seal. The oil is still in there, so I've got a rag in there. Then, I'm just going to use a bit of masking tape and a mask up this threaded section. I'm also going to mask up here where the anode sits so that the anode's on bare-metal there.

I'm going to paint the top surface here, because I do want to get this as smooth as possible by having that primer in the pitting here. Because we need our water pump to seat against here as well, we can always run a tap through the threads and clear those out again later. So, I'm not so worried about that, not really worried about painting the heads of the screws either that's fine. So, I'll do this little bit of masking and then we'll hang it up with some more wire and give it its first coat of primer. This is the primer I'm going to be using, in case you want to look it up. I found this to actually be quite good. This is the primer I used on the aluminum when I painted the glove box section the green machine, and the paint stuck really well there. It's actually an area that people step over and step on every day. So, it probably gets you know, people stepping over it, maybe five or six times a day. And it's been on six months to a year, and the paint stuck really well. So, it's given me quite a bit of confidence in this primer.

This company does also make a two-part epoxy primer that apparently is better according to their literature. If I was to be buying a primer specifically for this job. I probably would buy the two-part epoxy primer. But, because I got this, this is what I'm going to use. Alright, let's rig this up and start spraying. First step is always to give the can a really good shake. Then what I'm going to do, is make sure the nozzles clean. So, I do some test sprays you're not getting that splatter if it's a used can then. We're going to start from beyond the work. Start spraying and then spray at about a15 centimeter distance and we're going start before the work, spray across it to past it, then just keep going around in strokes.

You're not looking to get a solid coat of paint with this first spray. If you do, you're putting too much on. It's going to run so you're just getting a light coat on. It'll dry really quickly in this heat particularly, and we can put another coat on. Probably even do two or three, before I start giving it a light sand. I don't think this is going to have to dry very long at all. So, I think I'll just give it 15 minutes almost. Then just keep doing that, a light coat, another light coat, and then we'll bring it in. We'll have a look and we'll give it a go. I've now got the three coats of primer on. But I realized I had the microphone switched off when I was showing you. So, the idea was that I put these three coats on, and yeah, you can definitely see some dimpling and everything around there. So, I sanded it back using about a 400 grit sandpaper. In some places I've sanded it right back to metal to use the primer as a bit of a filler. I think I'm fighting a bit of a losing battle though. I really need to take another week to do another one or two coats of epoxy first to get it good. But, we're going to push on anyway.

So, now it stands it up I'm going go and put more coats of primer on. For the top coats, I've actually got two paint cans here. So, I might have an experiment and see what colors they are and compare them to the rest of the out board. This first paint is a Johnson/ Evinrude paint specifically. And it's the paint according to this that was used between 1981 and 1991. I think this outboard's a 94". So, may not be the right color. But, fortunately this paint is the one they use from 1972 to present. So, from 1972 onwards they use this, then in 81' they changed to this. Then, they changed again in 91'. But, it was always the same from 1972 onwards. Got it? What I'll do is have a look at both colors see which one matches best and then, I may need to blend the color up the leg a little bit. I'm not going to respray the whole out board. I can't be bothered, you know, but the leg is actually bad, the bottom, and improves as goes up kind of logically. So, I may already spray it anyway. And this may help me blend the colors in a little bit.

Here's my little test spray onto a glossy tap and die box cover. So, I think it sort of probably gives a good idea what they'll be like. The colors look identical the top half here is the BRP paint, and the bottom one here is the aftermarket one. The top one I felt the BRP one sprayed more nicely. So, that's what I'm going to use. This is it with the dry primer. I finished up far from perfect. But good enough for this outboard. I think alright, let's put that white on. It's worth showing here that with these first coats of the white, you can still see the gray primer through it quite clearly. You want these coats to be really light. Multiple light coats will give you a much nicer finish in the end. These first few early coats are dried now.

So, I'm going to give it a sand with an 800 grit sandpaper and then do a few more coats. The last coat of paint is dried now, it's all finished. I'll give you a look. There you go! So, perfect really, you know? Alright, so maybe there's a few things I'd do differently. Because the Internet's such a kind of forgiving place. So, I'll give you a close-up. Before we do that though. I guess one word about paint. So, lower units get a really hard life. And general touch up paints are not particularly tough. I'm often amazed how brand new outboards, very quickly, as in within a couple of weeks, don't have any paint left on the tip of the gearcase. If the boat's been running through shallow water though, even a good factory paint job will still come off relatively easily. If it's run through it's essentially sandblasted. I guess to help there you've got a few options.

I'm not quite sure powder coating is an option with these. Because you really don't want the powder to stick to the inside and various other places. Maybe if you seal it up you could powder coat it. Another good option probably is some sort of two-part epoxy paint, something really, really tough. I don't know if Evinrude / Johnson will make a two-part epoxy paint that you can use that's color matched. But, you may be able to take the paint they supply the touch-up paint, and say look I need something like this but, tougher. So, that's definitely saying it also could've been done differently. There's two other things on the preparation side of things that I would do differently. If I was looking to get somewhat of a top-shelf finish. One thing I'd invest in some sort of random orbital sander that had a bit of a sponge pad underneath. So it could sort of shape to the contours of this lower unit. And maybe you could get one that had a bit of a triangle shape. They are quite good for getting into corners.

So, I think that style might be quite good for doing this type of thing. To me, it wasn't worth going and buying one to do it. I was happy just to use a highly inappropriate sander. Which is a flat disc. I mean really, it's for grinding metal. That's just about that's how aggressive they are. But you know, if someone just makes do with what you got. The third thing is, if I wasn't under the time pressure to get this video out. I would have had another coat of the epoxy before I painted, possibly even a third coat. Just put more on, sanded it, put more on. You can't always see the problems, but you can certainly feel them. So, it's a case of sort of putting it on, letting it dry, sanding it off, running your fingers over it, putting a bit more on, sanding it off, repeat that process.

Most of the work is in the prep. The painting is actually reasonably trivial. I only did one coat of the epoxy in the sections that were bad. Which means the holes weren't completely filled. And the areas that previously looked good relative to the bad sections got nothing. And now they kind of stand out as the bad section. So, you know you get what you put into it. So, these holes here are the much deeper holes that had epoxy in them. They were much bigger before. But they needed one or two more skims over them to get them flush. The other thing you can see are these lines coming this way. This is the leading edge of the flap disk sander, it's a really aggressive sander. It's almost a grinding disc when it comes down to it.

And, you can see the leading edge does gouge in a bit, a bit of a foam pad, random orbital sander over this would do a much, much, much better job. But I didn't have one. You know, I'd buy one this is this small pitting here at the time I thought wasn't too bad compared to the big chunks that were out of the front here and I'm not worried about it but if I wanted to I could have actually put a really slight coat of the epoxy on there too, sanded it back would have given it a much more you know glossy smooth finish but I'm not so stressed about that. I put the new grille in temporarily just to make a look a bit nicer this is the taped up section, so when I get the anode in the mail it'll be in contact with bare metal.

This side came out a little better. I think the filling on the holes was better on this side. But, you can still just see the scoring a little bit from the flap disc sander. I had a rag stuffed in the gearbox so the paint's come in this front section. I'll have a look how far the bearing carrier goes in. It's different to the Yamaha style I'm used to where they sort of touch up against this edge and I might need to sand a bit in here. But at the end of the day, all I really need is the o-ring on the outside of the bearing carrier to make a good seal around the outside here.

All up didn't cost that much, was $40 for the sandblasting, and then probably $20 for the paint, and then maybe $20 for the primer. So, bet $80 all up. Next week, we'll definitely be getting back to the boat build. A few people have been asking what's happening with that. And yes, that I've been sort of you know, a bit slow with. Really, I was waiting just to buy a bit more epoxy and some more wood. And a big thanks to all the people who signed up to the patron account access. It really helped make that possible. So, I've got that stuff now and we'll be putting the longitudinals in in the next video. Alright, in the meantime take care I'll catch you later.