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Mhans

Mercator troubleshooting

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I have a 2011 Sunesta 264 with 8.2 Mercruiser with Bravo III drive..I have been plagued with stern drive corrosion for two years. Keep it in the Allegheny River in a slip at the yacht club. Change anodes every year (fresh water-magnesium). Have repainted the out drive last year before season....still corroded by the end of the season. Sanded and painted lower unit again this year before season...primed and painted with Mercruiser products....pulled it out last week and again, significant corrosion and pitting on the lower unit.

Is there any way to check the Mercathode system? Mercruiser suggests maybe a SECOND Mercathode system is needed. I don't know how to check the water around my slip for electrical potential.

Thanks

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weird, I keep my 2007 Bravo III in Lake Wallenpaupack and I get very little corrosion. I changed my zincs once but they really weren't bad at all. I don't know how to check your system but it's just odd that you have such an issue in freshwater.

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Yes, there are methods to check the waters you are in, and if your system is functioning.

Checking your own system is much easier and does not require special equipment, checking the surrounding waters is more difficult.

So, I suggest checking your own first. And, adding a second Mercathode controller is a 15 minute job if needed.

Do a quick search on here and you will find the test procedures.

I am on the Mon river south of Pittsburgh, and have no issues at all, so it can be solved.

good luck.

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Test your system on boat:

Mercathode System Testing
When the boat is in the water, disconnect the orange wire that comes from the anode at the mercathode controller. Set the digital reader to show milliamps. Connect the black meter lead to the terminal on the controller. Connect the red meter lead to the end of orange wire. If using the blue or black Mercathode controller, the reading should be 25 or less milliamps, to as much as 200 milliamps in saltwater areas. If using the red Mercathode controller, the readings should be less than 25 milliamps in fresh water areas to as high as 400 milliamps in saltwater areas.

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Here's what has worked well for me in brackish water. Install the red mercathode controller box with both the gimbal & transom mounted electrodes shown in paulswagelock's link. 3 coats of Trilux33 & new aluminum anodes every Spring.

There is also a test for the galvanic isolator but have never done it since my readings are within spec. Last test I saw 920-940mV.

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