How do you paint/maintain engine paint that lasts?

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Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
I rebuilt a single cylinder yanmar. The cast block fit in my oven so...I used a bake on engine paint. I then went back with regular hi temp engine paint on top of that to match the color on the engine. It looked great. I wire wheeled everything before painting and used acetone to make sure it was clean. 3 years later the aluminum tranny housing still looks great, all the aluminum parts look great, but the cast parts that I painted look like crap. Paint is peeling off where the edges of bolted together parts meet.
Looking at MaineSail's pictures of his engine I can't help but wonder what he is using to keep it looking like that?
I am going to start putting together a 2QM20 i have had sitting in my shop for a few years now. It is yanmar red now. The paint mostly looks good, but I want to go over it and make it look like new. What paint and technique will work?
 
RAD

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
Hermit.....having been an old motor head when I was younger I painted a lot of engines and only used engine paint only and never had a problem, maybe the base paint that you baked on is the culprit
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
RAD said:
Hermit.....having been an old motor head when I was younger I painted a lot of engines and only used engine paint only and never had a problem, maybe the base paint that you baked on is the culprit
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The paint on this 2QM20 looks original. Maybe not but it is worn and nothing seems to be under it. The single cylinder I rebuilt is grey. This other 2QM is red and is going to stay this way, because I don't want to have to redo everything. I want to paint over this old stuff that is on good.
The paint I baked on is doing fine on the aluminum but crap on the cast iron. It could have acted differently on the cast and could be the problem there.
I just want to use brush on engine paint to do this one because I am not tearing the whole thing apart. It looks like someone already did alot of work on this one. So I will do the clutch, pressure test the head clean it up and get it back together.
I just want my C30 to do 15 knots in rough seas. Is that too much to ask?
 
Rich Stidger

Rich Stidger

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Feb 10, 2004
4,235
Hunter 40.5 Warwick, RI
Hermit Scott said:
I just want my C30 to do 15 knots in rough seas. Is that too much to ask?
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Well, er..., yes that is asking too much.

But regarding your engine paint, I suspect that the salt water environment is causing the problem. Another possibility is poor prep, but it sounds like you jumped through all the hoops on this one.

What I have done on my engine where I have had corrosion and paint flaking due to (in my case) a leaking raw water pump is to use a metal corrosion/rust prevention system. I just applied this system this Spring so I can't yet report on the longevity of the process.

I used a product called Por-15. Do a google search and read up on it. I have a friend who rebuilt his 1966 Chevy and coated the entire frame with this stuff. The entire system- de-greaser, metal prep, and over-coat is a bit pricey- about $50, but I'm told this is about the best the industry has to offer. It works on all types of metal-iron, stainless, aluminum, etc.

I applied the system and then painted over the black Por-15 with my regular engine paint. Ask me again after my next raw water pump leak and I will tell you how well it worked....
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I just use a direct to metal machine tool paint.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
McCormick Interlock urethane. Just degrease with any good degreasing detergent, dry and paint. Just do touch ups as needed.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
"yanmars" get panted red when the get put in tractors! Orange actually is the Kabota color but perhaps my eyes are going.
 
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