bravo 3 corrosion

[rwarnett]

After 3 months in the water our twin Bravo 3 sterndrives have severe corrosion and need to be replaced. EP Barrus state that they will not replace them under warranty because some anodes (but not all) have gone. Has anyone had a similar problem and managed to successfully claim under warranty?

 

[duncan]

go straight to Mercury Marine in the States if you are happy that your anodes were up to it. They are extremely anxious to put the early BIII issues behind them and, with 6 fixed anodes and 2 mercathodes on each drive installation now they do seem to have finally got it licked!

On older drives you really have to stay on top of the anodes - and it's no good simply replacing the ones on the rams every few months.

How bad's the galvanic corrosion and how old are the drives?

 

[rwarnett]

The stern drives were installed in 2003, but we have been told that they are 1999 drives.
They are totally US, they need to be replaced.
Does anyone have any information about Mercathodes not working on tidal rivers?

 

[BrendanS]

It's probably not the mercathodes at fault, but the pysical anodes. Do you know what they are made of - Zinc, Magnesium, or Aluminium?

 

[duncan]

Re anodes they will either be aluminum for salt/brackish or magnesium based for fresh water. Mercury don't make a 'zinc' for the BIII (although some aftermarket suppliers are happy to provide them with guarantees that they will outlast the Mercury ones.... /forums/images/graemlins/crazy.gif).
I say this from experience with my 2001 BIII which 'melted' in 5 weeks when, unbeknown to me, the 'marine engineers' put aftermarket anodes on the drive and it was relaunched without my being there. We weighed them after the event and they came up just over twice the weight of the mercury parts for the same pattern/volume - they were also nice and shiny; just like new.
1999 drives will only have 4 anodes, and will probably have been installed with only 1 mercathode each - as Mercury Marine have been recommending 2 per installation (will try to find the service bulletin for you) I would suggest that your remedy is with the installer (if you had it done) or the survyor (if you bought it like that).
Interested in why they have been declared shot so easily - have you got some pictures; especially of the bearing carrier?
Some of mine are hanging around on here somewhere for comparison if you are interested - I can recomend Metallik Epoxy!
Where is the boat based?

 

[rwarnett]

she is moored on the Hamble, thats why i would like to know about mercathode working in flowing water. not much i can do to save the drives when bits of casing are breaking off.

 

[BrendanS]

flowing water will affect both the mercathode and the anodes to some extent.

You might want to contact mercruiser and ask for their "Marine Corrosion Protection Guide" I think it has a part number of P/N 90-881813 01. Everthing you've ever wanted to know on the subject

 

[duncan]

Richard - Hamble will be standard Mercruiser anodes for saltwater; you are probably identical conditions to me at the upper end of Poole Harbour in the middle of the tidal stream.

I don't think you have commented on who fitted the drives and how many mercathodes - if less than 4 and last year then I think you would have a serious case against the installer.