Painting a motor

jrs_diesel

jrs_diesel

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As part of the rebuild of my little 6 HP Johnson, I have a question about painting.

Since the motor is torn down, is it better to paint all the parts seperately/individually or when put together? Especially the powerhead, I'm a little worried about paint going where it shouldn't. How did they paint them at the factory?
 
sutor623

sutor623

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Re: Painting a motor

Oddly enough it looks like some powerheads are painted whilst still in place. The best way to tell is that if there is paint on the rubber washer/gaskets that go under the main screws that hold the powerhead in then the powerhead was painted while in place. Personally, if you want a stellar job, Id paint everything separately(to a point). Paint seems to start to crack at the points that parts meet together when you paint things all at once. Just be sure to plug all of your vacuum holes and cover all gasket surfaces. You can even leave the old gaskets in place, paint, and then change the gaskets. That is what I did with my 9.9 and it looks GREAT!!
 
sutor623

sutor623

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Re: Painting a motor

But, I WOULD put the powerhead back together before painting it. For sure!! Most of the powerheads are together if/when they are painted.
 
jmendoza

jmendoza

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Re: Painting a motor

If you look closely, it's apparent that they paint the power head once its assembled to the mid section, but they have not bolted on the carb, linkages, magneto and flywheel, fuel pump, or any electrics like the coils and wires. They mask off the intake manifod where the carb goes, the fuel pump bosses, and the end of the crank and bushing area where the magneto plate goes, and paint the engine. Use a couple old spark plugs to keep paint off the sealing area for them on the head. The block is already primed with a red oxide primer, as are all the other parts to be painted. On my 9.9 there is a grounding strap, and if your engine has one, be sure to bolt it to bare metal on the block and mid section before painting, also be sure the area where the coils go is bare metal so they are grounded.. I painted my block before bolting it on because it's easier to mask, and get good paint coverage. Oh, don't forget to mask the freeze plug so it's easy to read the stamped numbers on it.
 
1946Zephyr

1946Zephyr

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Re: Painting a motor

Yea, I typically painted a motor with the powerhead, midsection and lower unit bolted together and had all the shrouding and accessories off. Mask off the intake manifold, where the carb mounts up and the top, where the mag plate mounts. Use an old set of spark plugs in the head, so you don't worry about them getting painted. Newer motors of course, you have to pull the powerhead to get all the shrouds off, so then you would paint the powerhead by itself.
 
HighTrim

HighTrim

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Re: Painting a motor

I have found soda blasting well worth the money compared to manually sanding everything.

Once blasted and cleaned, thoroughally, let air dry or use an air gun.

Then 2 light coats of primer. After that, the initial colour coat is applied, within time restraints from priming, to save from having to sand the primer.

Then assemble the pieces. After assembly, a second coat is sprayed. Use low air pressure, and a HLVP system works well. May need more coats depending on runs, etc...

Hardest part about painting an outboard I think is all the angles you have to hit! Easier when not assembled.

When not assembled, I use the gaskets to trace patterns out of aluminum, minus the bore hole, just the outside edge and bolt holes, to bolt on, keeping the paint out of unwanted areas.
 
jmendoza

jmendoza

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Re: Painting a motor

I forgot to mention if you look at used spare Johnny and Rude powerheads, there are areas that are still red oxide primered because the power head was assembled to the mid section when painted, and the lower cowl prevented those areas from getting complete coverage of the color coat of paint. For that reason, its good to paint those areas if you have the power head removed. You can do a little touch up on the magneto linkage cap and bolt heads after assembly, and hit the mainfold, case and head bolt areas as well, plus the engine mount screw heads need a shot of color. Thus I spent a day doing the block and letting it dry overnight, assembled power head to the exhaust housing and touched up, let dry over night, and put on the fuel pump, carb, ignition, flywheel, starter and air box the third day. While waiting for the paint to dry I rebuilt the lower unit , resealing it and the water pump. The nice thing about using OMC paint is that is always sticks well to the original paint if you just scotch brite and clean it first. On raw aluminum , zinc chromate, but zinc oxide will do, the former is getting harder to find due to restrictions in some states. New paints, to comply with the EPA, have longer drying times, even lacquers.
 
jrs_diesel

jrs_diesel

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Re: Painting a motor

Thank you all for the great information. I'm sure my motor will look great by the time I am finished with it. :)

Thanks again.
 
Mas

Mas

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Re: Painting a motor

I would at the very least paint the powerhead and midsection as a unit, the lower unit as another job, the the swivel/clamp assembly as the third unit.

Mas
 
Mas

Mas

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Re: Painting a motor

Oh...
Check out "Chapter Five" in my signature of my Lark project.

Mas
 
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