Corrosion paint SX-A outdrive

[boatdude100]

Serious problem. Corrosion has compromised the seal of my (in the water behind the transom) SX-A outdrive trim motor. Bought the $2400 replacement trim motor and when replacing, discovered that corrosion compromised the seal (eaten away the metal) so water got in trim motor and killed it!

Need solid, reliable to paint outdrive and most importantly - mating surface of trim motor so it can again be flat and seal with new trim motor housing red seal.

Suggested process?
Best primer? Best paint? Where do you get it (in Canada or shipped)
How to make the gasket mating surface good again (now pitted and original paint peeled off)
Is my anode not working?

If it leaks again its another $2400! Thanks for your thoughts!

 

[Donald0039]

Look on forum boatered.com and there is a sticky post of painting aluminum. Is a multi step process to get it primed properly. Forget a self-etching primer if you want it done right.

Are you sure there are no corrosion issues? All zincs in place. None are painted?

During the boating season is the boat kept in a slip? Trailer?

 

[boatdude100]

Look on forum boatered.com and there is a sticky post of painting aluminum. Is a multi step process to get it primed properly. Forget a self-etching primer if you want it done right.

Are you sure there are no corrosion issues? All zincs in place. None are painted?

During the boating season is the boat kept in a slip? Trailer?

Thanks, I will look. Both zincs are there although one is aparantly magnesium (amazon purchase). Freshwater only, stored in lake then trailer through winter. Bad corrosion all around transom.
Has anyone tried marine-tek below the waterline?

 

[Scott Danforth]

I would be pulling the drive, motor, and then the transom shield. get soaked in oxalic acid to remove the corrosion, then bead blast. Then weld up any damaged areas, and face them off with a mill

from there, etching primer, epoxy primer sealer, and a good coat of 2-part paint.

 

[boatdude100]

Thanks for all input. Here's what I propose to do
1 powerwash
2 sand/scrape clean smooth (as little sanding/brushing as possible on mating surface of trim motor housing
3 Napa Metal conditioner (phosphoric acid-active ingredient in Alumniprep?) to clean exposed metal
4. Marine Tex to build up and smooth mating surface of trim motor housing
5 Some kind of etching primer. Suggestions? (Canada)
6 Paint- epoxy primer and 2 part polyurathane/epoxy paint HOWEVER I can't find one that says for use below waterline Suggestions? (Canada)

 

[Scott Danforth]

if you do not remove the corrosion down to good metal, it will be back under your marine tex and primer in about 3 months.

talk to your local industrial paint experts.

 

[Donald0039]

Is it at private dock or marina? Anyone else with a having issues? Typically corrosion is an issue in salt water, not so much in fresh. Do you use shore power in the boat when it's docked?

VP sells an active corrosion system. But again it's geared for salt water usage.

Get the right anodes for fresh water. Do you have anodes on trim tabs?

Get VP OEM anodes.

 

[boatdude100]

Update on what I intend to do.. after several days of research.. using products available in Canada 2024 (that excludes Alumiprep and Zinc Chromate Primer)

1) Sand, scrape and brush to good bare metal (thanks Scott)
2) "Metal prep Por 15" - 2 coats - don't wash off. Contains phosphoric acid like Alumiprep, and it leaves zinc coating. (Canadian Tire)
3) Wash off around trim motor housing where it is corroded and carefully apply/sand Marine Tex to build up and smooth mating surface of trim motor housing where it is corroded (Don't let this happen to you!!!) (The Chanderly marine supplies- Ottawa- not listed on their website)
4) Por 15 Rust preventative coating- Grey. 2 coats (see notes in link below) (Amazon)
4) Volvo Penta spray if bad colour match with existing outdrive paint
6) maybe a topcoat of clear Por 15..

To the following links and the ones in this post topic, I owe thanks and pass on their knowledge.

Outdrive Paint & Prep

I have been reading up on previous post but cannot seem to find the answer. I am preping my DP for paint. I do not have Alodine or Alumaprep. The outrdrive will be sanded for paint. I only boat in saltwater. I will try to keep as much of the factory paint as possible. The question is 2 fold...

forums.iboats.com

POR15 Metal Prep - Phosphoric Acid by another name?

I've used POR15 metal prep quite successfully before painting both new and old metal and need to buy some more. If you haven't come across it before Por15 metal prep. It is the ultimate in the relentless fight against rust. It not only dissolves away the rust it also etch primes the clean...

www.ukworkshop.co.uk

https://www.thehulltruth.com/boating-forum/1123127-por-15-a.html

Painting a Volvo outdrive - Cobaltchat.com

A Forum for Cobalt Boats. The Cobaltchat.com web forum provides an active community for owners of Cobalt Boats to share advice on using, buying, servicing, and enjoying Cobalt boats.

www.cobaltchat.com

Painting Aluminum (Especially Outdrives)

Painting Aluminum. It should be an oxymoron. But it happens. Especially aluminum out drives. I recently pulled my Mercruiser Bravo III. After 4 years of my paint job on it, not a single square inch of paint had eroded or peeled from the unit. Here is how I did it and some rules to remember when...

www.boatered.com

Rust Preventive Coating

Stop rust permanently with POR-15's Rust Preventive Coating. This anti-rust coating paint is designed to paint directly on prepped seasoned metal surfaces.

por15.com

 

[Scott Danforth]

The POR 15 will peal off by itself either right after if not before you splash

That stuff is now garbage

I did a whole writeup about 8 years ago and it failed. My buds in Scotland have been tearing his hotrod apart to reblast and paint his frame because it failed

Use the POR at your own risk. A rattle can of rustoleum would do you better

 

[Donald0039]

Either do a quick job with spray cans or take your time and follow the directions in boatered.com.

You need products specifically for aluminum. I would forget about the POR-15.

Until I figured out the corrosion problem I would use spray cans.