Painting a 75hp Powerhead

[yorab]

First of all, I'm a lousy painter and always have been. I'm not afraid to admit it. I'm also not afraid to tackle jobs that I'm not so good at. What doesn't kill you only makes you stronger...

I'm repainting my 1963 75hp Evinrude Starflite. I want this project to turn out well both mechanically (which I'm confident it will), and aesthetically (which I'm not so sure of due to my limited experience with painting). Therefore, I've done a LOT of research into painting blocks and I believe that I have followed all recommendations for a good paint job, but the results aren't as good as I had hoped.

The block was bead-blasted at the shop and degreased. When I got it home, I vigorously scrubbed all sufaces with dish detergent and very hot water. It was allowed to dry completely. Just before painting, I rubbed down all surfaces with acetone to remove all oils, grease, etc. From that point forward, I only handled the block with nitrile gloves.

I then made a make-shift paint booth in my buddy's shed. I covered the floor with plastic and made "walls" by hanging plastic from the rafters. I hit the bare aluminum with two light coats of Plasti-Kote Etching Primer. I followed the instructions on the back of the can. The primer coat was very even and covered all surfaces. You can see this in the attached pics. I waited the recommended 30 minutes and then began to apply Plasti-Kote Engine Enamel. I applied 3 light coats. By the 3rd coat, the paint was definitely thick enough. I even paid special attention to areas where the block casting had deep depressions. Then I followed up with one coat of Plasti-Kote Engine Clear.

I did this on Saturday afternoon because we had an unusual, low-humidity day here in central Pennsylvania. The temp was about 80 and the humidity was around 40%. When I looked at the powerhead today, I see that some areas are not well covered. Because the primer is a grayish color, the paint appears to be greenish where the yellow is not thick enough. I see too much greenish color for my liking.

Can I simply apply another coat of yellow to those areas that are not covered enough? Will the clear coat affect this at all? Will the paint get too thick in those areas? Any other ideas on how to get the green out? Thanks.

BTW, the covers will come off and be painted a different color, so I'm not concerned that they are not painted well.

 

[yorab]

Re: Painting a 75hp Powerhead

For those interested, I talked with a tech from Plasti-Kote today. Here's what he had to say:

"From your description, you may be seeing the effects of solvent entrapment combined with curing of the coating layers. If any of the layers was applied slightly heavily, this could be contributing to the discoloration you are seeing after application of the clear product.
Re-roughing the surface after a minimum 72 hour drying/curing time should help to stabilize everything. Once lightly abraded, the yellow engine enamel can be re-applied back over the existing layers provided there are no issues with adhesion.
Be careful with temperatures, hot (over 85 degrees) should be avoided as this will cause an aerosol layer to fast dry at the surface."

I'll wait until next weekend or later to lightly sand the areas that are still a bit greenish. I know it's hard to see in the pics, but believe me, some of the areas, especially in the deeper recesses and even on the outside surface of the intake manifold, look greenish in person. I'll check back in to let you know if I could acheive a uniform job.

 

[JimS123]

Re: Painting a 75hp Powerhead

Sounds like you did everything right and the mfg's recommendations are correct. I would guess you just didn't apply the topcoat heavy enough.

I have restored several dozen motors and I always chose not to repaint the powerhead. First of all, you can't see it, and when they are entered in a classic OB motor contest the judges don't remove the cowl to look. But mostly, I have a sense (right or wrong) that i don't want to disturb the old gaskets. Also, I would want to use a hi temp paint (like you did) but that won't match the original.

The only comment I have to make is that I would wait at least a couple of weeks before tackling the repaint. If what you have on now is not 110% cured, you'll lift the paint and have to strip and start all over. Been there, done that.

Also, with all the nooks and crannies, its doubtful that you can sand every little spot, so be aware that some peeling may result down the road.

 

[yorab]

Re: Painting a 75hp Powerhead

Thanks for the advice JimS123. I think that I will wait a few weeks before messing with it. I also agree with you that maybe I didn't acheive a thick enough topcoat before applying the clear. Therefore the darker colored primer is showing through and giving some areas the greenish hue. I was just being extra careful not to apply too thick. That has been the problem with my few other paint jobs in the past; I get too impatient and apply too much paint.

As far as the old gaskets go, I'm completely rebuilding the motor so the block was in pieces and all gaskets, seals and such have been replaced. Not a problem for my situation... Also, I'm definitely not going with original paint schemes here, as will be shown in the finished product

BTW, I think that I'll document my rebuild. I'm completely rebuilding the engine and I'm mostly rebuilding the boat. Where should I post this at?

 

[nash1970]

Re: Painting a 75hp Powerhead

looks real good !