Prep and paint for the LU

[oldrudedude]

I have a 73 Johnson 100hp. A PO must have left it in the water, because the original paint on the LU and mid section has blistered off up to the water line. The metal underneath has surface corrosion but no noticable pitting.

I would like to prep and paint it but am not sure what paint to use. I am not concerned about original color. I am more concerned about protecting the underlying metal from further corrosion, so need something that will bond well to the metal. I plan to sand the oxidation down to clean metal. Can I use an automotive engine enamel spray can paint with a zinc oxide primer? Or what? any suggestions?

 

[bktheking]

Re: Prep and paint for the LU

I use zinc oxide primer and OMC paint and all the metal parts of my motors and they turn out really well. Prep is key, make sure you get any grease,dirt, and oxidization off the metal. I've used krylon paint for the cowl with clear coat and it looks amazing, you may want to do the cowl as well to have it all looking like new.

 

[dewdiggler]

Re: Prep and paint for the LU

Use zingon The Oxidation, It Works Great!
Make Sure To Were Rubber Gloves
It Will Clean All The Oxidation Off And Leave The Paint Looking New

 

[wilde1j]

Re: Prep and paint for the LU

Chromate primer is the thing to use on aluminum, not a zinc oxide based primer. For a nice finish, lacquer will give a super air dry finish ... just make sure to spray in a warm environment to rapid drying w/o dust pickup. Tempo Products used to market both before that went out of business a yaer or so ago. Regardless of the final finish, use a zinc chromate primer. Until not many years ago, most new motors were painted with lacquer.

 

[bktheking]

Re: Prep and paint for the LU

THat's what I meant zinc chromate, i'm sick with a bad cold, shoot me

 

[oldrudedude]

Re: Prep and paint for the LU

Thanks all for the helpful responses.

oldrudedude

an automotive engine enamel spray can paint with a zinc oxide primer?

bktheking

I use zinc oxide primer and OMC paint and all the metal parts of my motors and they turn out really well.

wilde1j

Chromate primer is the thing to use on aluminum, not a zinc oxide based primer.

Actually, zinc chromate primer is what I was referring to also.:redface: I had a can of it in my hand at CT today but decided to wait for your responses before I bought it.

What is "Zing"? I don't believe I have ever seen that product.

 

[jbjennings]

Re: Prep and paint for the LU

my .02,
Wait for a day with really low humidity. Use the same brand of paint and primer if possible.
JBJ

 

[oldrudedude]

Re: Prep and paint for the LU

my .02,
Wait for a day with really low humidity. Use the same brand of paint and primer if possible.
JBJ

I do that.

 

[dewdiggler]

Re: Prep and paint for the LU

You Can Get Zing From A Your Local Marina
You Put It In A Spray Bottle, Spray It On Your Lu Let It Sit And Watch It Work! Wash It Down With Water.
If You Have A Lot Of Oxidation Might Need To Do It A Couple Times
And Some Lite Scrubbing

Carefull Tho, Its Toxic To Touch Or Smell.

It Will Not Hurt The Paint At All.

I Had Piles Of Oxidation On My Motor When I Got It.
And Wasnt Sure What To Do About It And My Brother Gave Me A Bottle To Try And It Worked Great!

Good Luck, Dew

P.s. I Will Take All The Tips On Sanding And Painting The Cowl

 

[bktheking]

Re: Prep and paint for the LU

For sanding the cowl I used a light grit sand paper, say 600, I sanded the decals off with an orbital sander with heavier grit. Then I cleaned the sanding reminents off with a tack rag. Buy yourself some automotive grey primer, whatever colour you want to paint it, I chose Krylon white for my 9.9 and then shot it with some clearcoat at my dads shop, he's got all the proper paint supplies for painting anything. Just make sure you apply several light coats of primer and sand the primer LIGHTLY with your final coat. Make sure all paint types are the same, if you are painting laquer use all laquer paints, if painting with enamel make sure you buy all enamel. If you try spraying enamel clearcoat over laquer it will spider web and then you have to start all over. Make sure you paint in proper temperatures, right now here it's 5C, not the right temp at all. The decals I bought were from Nana on ebay, they were good decals, easy to apply. Once they were on and all the bubbles were gone we sprayed the clear.

Here are some pics of the primer and finished product.

 

[AndyD]

Re: Prep and paint for the LU

The cowl came out real nice!

For those that need to paint a whole motor and have a compressor and spray gun (you can buy a real nice gravity feed gun at Harbor Freight for about $25) try what I did to my OMC Sea Drive a few years ago;

Find an Auto-Body paint supply store and ask them to match or provide paint in your desired color(often they will have the color codes or can look them up for stock colors). I used Dupont Centari Acrylic Enamel but any good quality acrylic enamel should do. Acrylic enamel is safe enough for use at home with a standard respirator that you can buy at Home Depot but stay away from catalyzed urethanes as they produce very toxic fumes and special breathing devices are needed for these. One quart should be more than enough.

Totally clean and degrease all parts. Dis-assemble and paint separately as many parts as you can especially where processable nooks and crannies exist. Remove or mask off decals gaskets etc... Remember you cannot get something too clean you must be meticulous about this!

Sand and prime bare metal areas with zinc chromate as described earlier. Sand all or as much surface areas as you can to degloss and give new paint a tooth. Paint all surfaces to be finishcoated with high build automotive primer (also obtained from auto paint supply store). Apply extra coats of high build to fair areas where paint was chipped or sanded off. Wet sand as needed and apply additional coats to obtain a smooth surface.

Wash down again with soap and water, wipe with a tack rag, and then wipe with prep solvent. Apply masking tape/paper. Wipe again with prep solvent to remove the oil from your fingerprints.

Mix the paint with proper reducer (thinner) for your temp and humidity mix in a catalyst/hardening agent and spray 3 coats. You can find some good tutorials on spray techniques online so I won't get into that here. Finally you can wet sand and apply a clear coat if desired. acrylic enamels look just fine without them but the clear coat will make your finished product look almost flawless with more gloss and it will likely stay looking better for longer.

All in all a lot of work but the results are impressive, and if done right you can actually make your motor look better than it did when new.

 

[dewdiggler]

Re: Prep and paint for the LU

VERY NICE!
thanks for the advice

 

[oldrudedude]

Re: Prep and paint for the LU

dewdiggler,

Who makes Zing? The marine supply I contacted has not heard of it. I did a google search and came up with nothing.

 

[Mandrake35]

Re: Prep and paint for the LU

When I did my 9.5 I used a dremel with a sandpaper disc to knock off all the old paint...thoroughly degreased the whole thing, even using brake cleaner to get the tough bits. Then I used a zinc chromate primer (it was bright yellow) for 2 light coats. I then used an automotive filler primer for 2 light coats. The finishing coat I used was Ultra flat Krylon Camo colours, because my motor is used for duck hunting, but I'm confident with the 4 primer base coats any top coats would have come out great. The lighter the coats you give it the better the final result will be. Its very tempting to try and get it all done in one coat...I would advise against it. I think My motor came out really well. Good luck

 

[oldrudedude]

Re: Prep and paint for the LU

Nice camo job. How did you mask it to have it come out looking like reeds?

I think you are right. The secret of a lasting paint job is not necessarily what you use for a top coat. Prep and prime are key. I don't plan to take the lower leg apart so I think the biggest challenge will be sanding and cleaning in the corners and crevices.

 

[bktheking]

Re: Prep and paint for the LU

Not taking it apart may make the job more difficult, I tossed around the idea of not taking my 2 9.9's apart that I painted but in the end i'm glad I did, a little extra work but the final product is perfect as compared to not doing it i'm sure.

 

[oldrudedude]

Re: Prep and paint for the LU

I just tried cleaner some of the corrosion from the lower leg with a 4 1/2 inch sanding disc on my electric drill. Appears it will be a much bigger job than I first thought. There is a LOT of corrosion and pitting. Rather than being too aggressive with the sanding and taking off a lot of metal, maybe I should be cleaning the pits out with muriatic acid or something like that. What do you think?

 

[bktheking]

Re: Prep and paint for the LU

When it came to pitting I just left it, sprayed it and hoped for the best. It's aluminum for the most part so unless you are willing to put a whole pile of time in effort getting it perfect just leave it. If it were a showpiece to sit in my office that's one thing, it's going on a boat completely different. The paint started coming off the leg of the 9.9 from the oil running onto it after 2 days, they are very hard to keep in perfect shape, you'll see.

Not to mension if you have a wife/gf like mine who doesn't notice the nice shiny new cowl you left to dry in the garage and happens to let the fishing rod fall onto it 2 days later and then play stupid when you ask why there is a dime size chip of paint missing on the cowling you spent $50 in material and 5 hrs of work and prep time.......well you get my point.

I sold it a week later (the motor)!! LOL

 

[samo_ott]

Re: Prep and paint for the LU

Good thing you clarified that it was the motor you sold a week later!

 

[oldrudedude]

Re: Prep and paint for the LU

The paint started coming off the leg of the 9.9 from the oil running onto it after 2 days, they are very hard to keep in perfect shape, you'll see.

Was it just the top coat that came off or the primer too?