Engine Painting

Pamessina13

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Feb 18, 2013
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35' JC
Hi guys,

what primer should I be using for repainting my engine? I know it should be a zinc chromate primer but I can seem to find a rustoleum version locally. I guess I could buy the moeller version but they make a zinc phosphate and zinc chromate. I plan on using the factory CAT paint for the topcoat.
Thanks!
 

c1steve

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Jan 30, 2017
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The most important part is to get all the grease and oil off of the engine. Warm the engine up, spray with Foamy Brite engine cleaner, then use a small toothbrush style wire brush. Go over the entire engine that you can get to. Do this three times, rinsing each time. Then run until fully dry. Mask off.

The Rustoleum brown primer is pretty good, at least the brush on version is. I have use Cat yellow paint, but am not familiar with a Cat primer. Just remember the prep is 90% of the job. Best to paint the engine when warm as well.
 

Keelboater

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Oct 3, 2013
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Clinton Harbor
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35' Bruno & Stillman
For an assembled motor with all hoses and wires in place, my preference is to use epoxy primer applied by a good brush. Then paint with two part polyurethane paint like Perfection, again by using a brush. I just use a 2" chip brush with a dabbing action to apply the paint. No brush strokes. The dabbing action will enable that paint to flow out evenly in all directions and give you a nice finish that will last much longer than any rattle can job. Not only does the brush method work good, it saves you hours of masking off things you do not want over spray to get on. If you happen to see a run forming, just dab it with the brush which works like an eraser. It's that simple. It might sound crazy, but it works great. There are enough colors available to mix for a finished blend of just about any motor color. Thinning is not usually required but you should have a little reducing solvent on hand just in case. The only down fall is the cost when compared to rattle cans, but you get what you pay for. Give it a shot or at least try an experimental job before diving in.
 

Brooksie

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Cape Cod
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Bruno-Stillman 35
Two things NOT to do
Don't try to paint cold metal.
Don't use UHT (Ultra High Temp paint) known as header paint except on turbo housing and then only if you are able to bring it up to temperature to bake it on.
 

Blitzen

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Sumday Isle, RI
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Flowers Boat Works 46 hull #1, Flowers Boat Works 36 hull #1, Wayne Beal 28 Hull #1, Repco 30 1968,
Hi guys,

what primer should I be using for repainting my engine? I know it should be a zinc chromate primer but I can seem to find a rustoleum version locally. I guess I could buy the moeller version but they make a zinc phosphate and zinc chromate. I plan on using the factory CAT paint for the topcoat.
Thanks!
Interlux Brightside Matterhorn white. Way better gloss and more durable than the CAT factory rattle can.
 

DotRat

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Jul 12, 2019
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Beantown
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Row Boat
Yeah I agree with prep being the MOST important part. I use Castrol super clean and steam clean the motor three or four times. Make sure you are in a ventilated area cause that stuff concentrated will knock you out. I have done brush and spray and if you are good with the sprayer I find that is a lot faster and can get in the nooks and crannies. If you are not well versed stick with the brush way less drips and you can get the same coverage. Make sure to wear some sort of mask cause all those fumes will KILL YA! Good Luck!
 

Pamessina13

Lieutenant
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Feb 18, 2013
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Boat Make
35' JC
Thank you for the help guys! I’ll be sure to post a picture when it’s done
 

TCL

Captain
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Jan 29, 2014
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Location
Annapolis MD, formerly Huntington NY
Boat Make
Sabre 36 The Captain's Lady
I’m facing the same project, on one of my Yanmar‘s so a few questions.

1, My boat is currently shrink wrapped so ventilation will be a problem. To remove fumes I’m planning on using a shop vac with an exhaust hose running outside the cover, is this adequate?

2, The boat is on the hard and not able to run, is a 1500 watt bathroom heater enough to warm up the engine for painting?

Thanks
 

Keelboater

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Oct 3, 2013
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Clinton Harbor
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35' Bruno & Stillman
The heater will not warm the motors that much because of the cold liquid masses they contain. But it will eliminate condensation. You can try using a heat gun as well but don't expect miracles. Heat lamps probably work the best. As for ventilation, I just wear a respirator, paint, and call it a day. Ambient temp in the bilge and a dry surface are the most important. A cold surface may contribute to runs because solvents do not flash off as quickly.
 

c1steve

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If you have a water heater on board, using hot water helps tremendously with taking the oil film off. Hook up a hose to the drain fitting would be best.

I agree that epoxy primer is best. I used to spray on Devoe Bar-Rust 235. Would heat it in a paper cup in a microwave oven for 10 seconds or so, that gave me about 2 minutes of working time. Worked great.
 
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