bravo 3 corrosion issues
05-08-2007, 09:44 AM
#1
Registered
Thread Starter
bravo 3 corrosion issues
my father has on 01 Searay 260 Sundancer with a 454 mag mpi and a bravo 3. This thing goes through zincs like crazy !! Over heard someone saying something bout a recall due to contaminated metals used when lowers were built. Anyone know anything about this ? The lower skeg and carrier bearing housing are starting to deteriorate and have never seen this b4
05-08-2007, 11:56 AM
#2
Geronimo36
Gold Member
To begin with the B3's are more prone to corrosion than any other merc. drive because of all the extra SS in the shafts, daul props etc... It attacks the aluminum first cause it's softer.
Most of the time though, I saw this was an issue when someone had reversed polarity at the dock and/or did not have a mercathode system. Was the motor ever replaced? Check the grounding straps from the transom to the motor and from the bellhousing and gimbal ring to the transom assy. on the outside.
My buddy has a Formula 34PC with T-B3's and he replaces zincs twice a year.
Worst case, get one of those zinc fish's and clip it to the neg. battery terminal and hang it in the water.
Most of the time though, I saw this was an issue when someone had reversed polarity at the dock and/or did not have a mercathode system. Was the motor ever replaced? Check the grounding straps from the transom to the motor and from the bellhousing and gimbal ring to the transom assy. on the outside.
My buddy has a Formula 34PC with T-B3's and he replaces zincs twice a year.
Worst case, get one of those zinc fish's and clip it to the neg. battery terminal and hang it in the water.
Last edited by Panther; 05-08-2007 at 11:59 AM.
05-08-2007, 12:12 PM
#4
Geronimo36
Gold Member
05-08-2007, 12:52 PM
#5
21 and 42 footers
Platinum Member
B3's corrode like crazy, much worse than the B1's. Why do you thing volvo came out with the composite drive. Looks like it's time for a lift!!! 
05-23-2008, 12:45 AM
#6
Remove props either acid etch or beadblast. Coat them . I like flat black paint, Clean bearing carrier with SS wirebrush, remove all corosion, and clean all residue, coat with zinc chromate primer at least two coats then topcoat. This at best will slow down what corrosion happened and give you more life until the carrier lets go.
No big deal to change carrier either before water gets in and you loose oil film on gears and wear pinion right out.
Use the recommended aluminum magnesium zincs they are softer than the case of the drive.
The most important thing to understand in my opinion is that the eletrolysis that's going on doesn't know the difference between the bearing carier or a zinc or some other vulnerable part .
Basically the Anodes(not zincs) give up electrons and decompose
Even though parts like the bearing carrier may be anodized or hardcoated from the factory, its only an electrolitic building up and sealing of the oxide layer that naturally forms on an aluminum surface. Once scratched or compromised, corrosion will take over.
Last time I bought them, the continuity kit was $16 from Bam marine. It includes all the little ground straps and screws as well as instructions.
You can stack 2 Mercathodes for increased protection. It may drain battery and you may not find this to be acceptable. You can get a test probe to stick in the water to test the operation of the Mercathode system.
Beware of people that leave thier boats plugged in to shore power all summer and never use their boat. They are being selfish and lazy. I have seen first hand many times the bad results of this carelessness. A stainless prop or thru hull fitting can have holes eaten in it. I had a boat sink because of this when a thru hull got compromised because of the guy 20 feet away in the canal that was "plugged in"/ Actually I should have grounded the fitting.
The reason for everything being grounded is so important, because if not, one part may get attacked by electrolysis.
Think of it as going into a bad neighborhood in the middle of the night by yourself wearing elaborate gold jewelry etc , you are looking for trouble. You would be much better off if you rolled thick with a big group, the more of you that were together, the less chance someone will get singled out and maybe killed.
I didn't catch where you were boating, but salt is sodium chloride, and sodium is a metal. What is going on is we are creating a battery whan we combine all these dissimilar metals in water which is made up of Hydrogen and oxygen. Even freshwater is hard on bravo 3's
I serviced a boat with them on the Upper Hudson that had bad corrosion. That was awhile ago, the drives were replaced by Merc. under warranty. 1997 boat, job was done in 1999. Hope this helps, BBB
No big deal to change carrier either before water gets in and you loose oil film on gears and wear pinion right out.
Use the recommended aluminum magnesium zincs they are softer than the case of the drive.
The most important thing to understand in my opinion is that the eletrolysis that's going on doesn't know the difference between the bearing carier or a zinc or some other vulnerable part .
Basically the Anodes(not zincs) give up electrons and decompose
Even though parts like the bearing carrier may be anodized or hardcoated from the factory, its only an electrolitic building up and sealing of the oxide layer that naturally forms on an aluminum surface. Once scratched or compromised, corrosion will take over.
Last time I bought them, the continuity kit was $16 from Bam marine. It includes all the little ground straps and screws as well as instructions.
You can stack 2 Mercathodes for increased protection. It may drain battery and you may not find this to be acceptable. You can get a test probe to stick in the water to test the operation of the Mercathode system.
Beware of people that leave thier boats plugged in to shore power all summer and never use their boat. They are being selfish and lazy. I have seen first hand many times the bad results of this carelessness. A stainless prop or thru hull fitting can have holes eaten in it. I had a boat sink because of this when a thru hull got compromised because of the guy 20 feet away in the canal that was "plugged in"/ Actually I should have grounded the fitting.
The reason for everything being grounded is so important, because if not, one part may get attacked by electrolysis.
Think of it as going into a bad neighborhood in the middle of the night by yourself wearing elaborate gold jewelry etc , you are looking for trouble. You would be much better off if you rolled thick with a big group, the more of you that were together, the less chance someone will get singled out and maybe killed.
I didn't catch where you were boating, but salt is sodium chloride, and sodium is a metal. What is going on is we are creating a battery whan we combine all these dissimilar metals in water which is made up of Hydrogen and oxygen. Even freshwater is hard on bravo 3's
I serviced a boat with them on the Upper Hudson that had bad corrosion. That was awhile ago, the drives were replaced by Merc. under warranty. 1997 boat, job was done in 1999. Hope this helps, BBB
05-23-2008, 01:05 AM
#7
Basically Merc recommends an anode change mid season. Especially if anodes get consumed, they should be considered to be doing thier job. Some people get the props epoxy coated.
With these drives an ounce of prevention is worth 10 pounds of cure.
Is it any wonder Mercruiser added an extra cavitation plate anode and a propshaft anode on the later drives due to warranty issues ?
Good judgement comes with Experience.
Experience comes from bad judgement !
God help us all, We need it ! , BBB
With these drives an ounce of prevention is worth 10 pounds of cure.
Is it any wonder Mercruiser added an extra cavitation plate anode and a propshaft anode on the later drives due to warranty issues ?
Good judgement comes with Experience.
Experience comes from bad judgement !
God help us all, We need it ! , BBB
05-23-2008, 11:06 AM
#8
Charter Member
