Bravo III drive corroision issue


C

castines

Administrator
Any of you had the Bravo III drive issue ? I think it was from 99 to 01 or 02. If you have a cone zinc on the end of your props I think you are good.

Mine are 5 years and still going strong.
 
I have had severe corrosion issues in fresh water with a 1994 Formula 34pc with bravo III drives. I had to replace them in 1999, due to a seal leak and the bearing carrier could not be removed. I paid for the replacement, and got Merc involved. They could not find anything wrong with the boat, marina electricity, or any reason that they corroded except that they were designed for lake boating and the fast water of the rivers in Pgh. caused the problem. Isn't that a crock.
Every year since then,I had Merc replace both drives under warranty. Every time, they checked out every possible source, and could not find a problem. They even replaced drives with the newly designed drives, with more anodes and a cone shaped zinc on the prop shaft. that did not work either. The only answer was to add the old style mercathoide system to the transom. (hockey pucks). after installing two sets, the readings finally were where they should have been all along.
I took readings daily, and found that anodes will get a sort of crust on them after about six weeks, and are no longer effective. Merc recognizes the problem, but will not admit that it is their fault. I had enough of expensive anodes, and maintenance, therefore i purchased a Volvo composite. Best decision I ever made.
 
mine is an 01 with about 300 hours. Drives are original and I use Magnesium in fresh water. I slip in fresh and boat is salt. So far so good.
 
My 1994 was used exclusively in salt water for the first two years. There were no signs of corrosion when purchased. I changed all anodes from zinc to magnesium before launching into fresh water. six weeks after, is when i noticed the corrosion. Do not have any answers why this happens to some, and not others.
 
It is amazing how nobody is able to figure why this happens although I think Merc might know but won't say. I think Volvo also knows and that is why they came out with the composite drive and Merc will soon.
 
The bearing carrier in front of the prop is made out of a magnesium alloy. Then you have 2 reel big props that conduct electricity and cause galvanic corrosion. The stainless makes a great conductor. Thats the reason. The newer drives have a cone zinc on the end of the shaft to help the issue. You can also have your older drives modfied to get that cone zinc.

No way around it with out composite drives.
 
That is true, it is like a giant battery in the water. However, it does not appear to happen to every Bravo III or DP drives out there. There are a lot of external factors that can speed this process and some of them ,I believe, are connected to the drive assemply itself.
 
I see know evidence on my drives yet. I hope to get 1 more season out of the. Maybe Merc will have composite by summer 2007 ::)
 
MERC HAS COME OUT WITH A NEW DRIVE CALLED SEACORE. IT HAS A 5 YEAR CORROSION WARRANTY. iMAGINE THAT!!!!! yOU CAN BET THAT THEY WILL RUN AND HIDE WHEN THINGS HAPPEN, AND BLAME THE OWNERS FOR BOATING IN THE WRONG ENVIRONMENT. THEY HAVE ALWAYS BEEN BEHIND VOLVO IN TECHNOLOGY.
 
I have no Volvo experience, but from an observer's point of view, I do think Merc tends to "stick with what works" and take the safe way out, where Volvo takes some risks in researching new technology.

I give a lot of credit to them for taking those chances and investing $$$ researching, whether they fail or succeed! ;)

That said, my 32 year old mercruiser powerplant is still going strong ;D
 
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