Boating How-To’s - Yamaha engine bracket corrosion
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04-16-2012, 12:26 PM
the brackets on my F250s are corroding at an alarming rate. I need to do something this season. Engines have 6 seasons on them. Here are some pics. Anybody experience this before and what did you do. Want to avoid this again in the future as well once replaced/repaired.
What brand of anti-fouling paint is that?
04-16-2012, 01:33 PM
It appears a good part of those brackets stay immersed.
As Andy is mentioning, if they are not painted with an anti-fouling paint, then they wont stand much of a chance in a constant bath of salt water. No motor would, I would think....
The housings on the tilt/trim motors will rust the worse if left in that environment. Make sure that they get some special attention..
04-16-2012, 01:45 PM
I will check on the brand of anti fouling paint. Yes, they are under water up to the line shown. Last year’s paint seemed to just disappear. This pic is after power wash. I do get some growth on it and scrape/brush it off during the season. Maybe electrolysis is at work as well. Since the bracket is made out of aluminum (?) should I assume no copper based anti fouling paint? I’ve had the work done by a third party each year. Any suggestions of what should go on this now?
04-16-2012, 03:15 PM
Clean it up really good with a wire wheel. When you have a good clean surface to work with apply a coat of zinc chromate primer, the stuff I use is by Moeller and is found at most marine stores. Then, with the primer coat down, you can apply a good coat of Trilux 33 (by Interlux) or similar anti-foulant designed for outdrives, lower units, etc.
Both the zinc chromate and Trilux 33 come in 12oz. spray cans and should be more than enough for the job.
Also, check the condition of you zincs. Make sure they are in good shape and of course be sure not to paint over these.
04-16-2012, 04:33 PM
They have already been cleaned up since those pics. thanks Bayman for the great advice.
My point with the AF paint is if it has copper in it, and its touching the engine bracket(it appears it is) you might be having a corrosion issue from those 2 dis-similar metals under water. The aluminum in the bracket parts being the less noble metal of the 2, causing that problem.
Maybe that's normal for engine brackets in constant saltwater immersion. I don't know...we are in freshwater.
04-16-2012, 04:50 PM
Someone else has told me that very same point. I will make sure that doesnt happen again.
04-18-2012, 02:33 PM
It sort of looks like you've got an electrolisis problem.
Caused by bottom paint? Caused by a boat moored next to you in a marina? Bad ground in your own boat? Caused by shore power? Bottom paint does not have to "touch" the motor. to be an electrolitic problem. It only has to be near the boat if stored in the water, It can evevn be from an agressive bottom paint on a boat moored next to you.
Unfortunately most of the "zincs" sold today are made to last longer, duh! Rather than be real zinc. If stored in the water you may need a 'sacrifical anode" (block of zinc, copper wire, attached to ground terminal, hung in the water) if boat is stored in water.
If it is a case of imersion in salt water and nothing else you obviously need to "bottom paint" the parts after cleaning them up.
04-18-2012, 03:23 PM
keysdiver, I am having a zinc made up to hang off the boat in the water as you described. More excellent advice.
I'm leaning to think it's due to copper paint. Where I boat there are alot of pontoons. Some are painted with the incorrect paint (has copper) and over time the toons develope pin holes.
I boat in saltwater and my bracket is also under water. 6 seasons and no damage like yours. I'm using Pettit antifouling paint for METAL.
04-19-2012, 12:33 PM
The trilux 33 is going on this week after the primer. I will post up photos after cleaned up. I looked into replacement parts and that got real expensive real fast.
04-19-2012, 01:57 PM
Don't get too fancy with a zinc to hang. just find someone who will sell a "block" and drill a hole.
Electrolisis in marinas & galvanic action is common in marinas, especially when shore power is present. Another fact is they both affect the life of bottom paints. Copper or tin based.
04-27-2012, 07:37 AM
I had the exact same problem with F225s - when I found out it was several grand to replace, I removed the the trim mechanism, which is really easy to do, and had that assembly as well as the bracket that remained on the boatsoda blasted and repainted with an OEM paint match and a urethane clear coat. I then used the tri lux spray paint as well. I have found the key is that when you pull the boat, power wash the barnacles and crud immediately and try to scrape off with a plastic or wood scraper. In the spring, repaint again with tri lux. You really have to put on a lot of tri lux.
If you are going to use Trilux you must use the Primocon primer, to isolate the aluminum from the paint. Trilux does use a form of copper but it is not as corrosive as the copper in regular bottom paint. BUT, you still need to put on 3 coats of Primocon and 2 coats of Trilux.
Pettit also has an antifouling paint for aluminum that has no metals in it, that might be easier on the aluminum. Its tough to get any paint to stick to aluminum in salt water.
04-29-2012, 09:52 AM
The copper in the paint could be the culprit but you must also make sure the horseshoe zink under the engine is there and is propperly installed. It looked in the picture like maybe it was gone. I had the yard strip the bolts holding the zinc and it fell off. After just one season I needed new mounts and trim pump. It really sucked!