If there’s a common thread linking the reports in our complaint file, MerCruiser certainly isn’t saying. Aside from giving us a few clues and stating that “there are a lot of different issues” causing the problems reported to us by owners, the company still hasn’t given a complete explanation. In recent weeks, however, a Merc spokesman has opened a dialogue with BoatUS.

Corrosion on Bravo IIIs seems to stem from the galvanic reaction that occurs between the massive stainless steel props and the lower unit housing and drive components, which are made of aluminum. Particularly vulnerable, it seems, is the aluminum bearing carrier, a sleeve through which the prop shaft passes into the aluminum drive housing. Once this seal is compromised, water can enter the gear case.

As troubling and expensive to correct as corrosion damage is, the Bravo III situation also highlights what appear to be serious lapses in the customer service response of one of the nation’s largest and best-known marine engine manufacturers. The boat owners we wrote about were in turns frustrated by MerCruiser’s slow response, irritated by the offhand way in which their complaints were eventually addressed by Merc personnel and worried by their dealers’ inability to diagnose the source of the problem or guarantee that it wouldn’t happen again.

MerCruiser, located in Stillwater, OK, is the inboard engine and lower unit wing of Mercury Marine of Fond du Lac, WI, where Mercury outboards are built. BoatUS receives few complaints about Mercury outboards and customer service response from that facility is generally good. Brunswick Corp., parent company of Bayliner, Sea Ray and Maxum boats, among others, owns Mercury and MerCruiser.

In late November, BoatUS sent MerCruiser president Barry Eller an inches-thick package of complaints. By then, response to the “Corrosion Burns I/O Owners” article had swelled our case file to 117 reports. As with earlier correspondence on this subject, we asked MerCruiser for preventive maintenance tips that could be passed along to owners. We asked Merc to address Bravo III design features that place dissimilar metals in close proximity, creating a condition ripe for corrosion. And, we asked the engine maker to explain whether certain Bravo III components were modified to mitigate corrosion.

We received no response from Eller. A Merc spokesman later told us, “As president of our OEM [original equipment manufacturing] division, he does not have direct supervision over our customer service function.” Even so, the package of complaints apparently was not forwarded to anyone with the authority — or the interest — to handle them.

BoatUS has received no corrosion damage complaints involving lower units manufactured by Volvo Penta, the only other manufacturers of twin-prop lower units and the second largest lower unit producer in the U.S. As for corrosion reports on outboard engines, we’ve gotten only four over the past five years.

“There are a lot more MerCruisers in use than there are Volvos or any other brand of sterndrive,” according to Tom Mielke, Mercury Marine’s corporate communications director. “That alone will create a pretty big slant toward MerCruiser owners being BoatUS members. And outboards, which do corrode if not properly maintained, have the advantage of being able to be tilted completely out of the water. A lack of electrolytic solution [for example, sea water] will greatly diminish the chances for corrosion.”

“These statements are not intended to diminish what your members are seeing and feeling about the products they own,” Mielke added. “I do need to make sure, though, that we're both viewing the situation from the same perspective and comparing apples to apples.”

The majority of Bravo III complaints reported to BoatUS involve lower units installed as new equipment on 1997 through 2001 model boats, about two thirds of which are used in saltwater.

Owners describe damages severe enough that complete lower unit replacement is sometimes necessary. They describe aluminum housings pitted with holes “like Swiss cheese,” and skegs and cavitation plates so brittle they crumble in the hand. Merc offers a three-year corrosion warranty on Bravo III lower units, so owners say initial replacements and repairs have been covered by the factory, albeit reluctantly at times. Subsequent, out-of-warranty failures, even identical ones, are not. According to information reported to BoatUS, lower unit replacement costs run $6,000 to $8,000.

When MerCruiser’s Mielke finally took our package of 117 complaints in hand, he said that the company had no records for more than half the corrosion complaints.

“We just weren’t showing any reported issues,” he said. “Many of our claims are processed through our dealer network, so they are entered online by the dealer. To speed transactions and get boaters back on the water, many claims are handled automatically.” Apparently, MerCruiser customer service in Stillwater doesn’t become actively involved.

Further, Mielke said, “Many of the corrosion-based complaints that you are seeing are for engines out of the three-year warranty corrosion period. Our company is unique in offering this warranty in the first place and we feel that we’re very fair in our administration of it. Unfortunately, this isn’t satisfactory to a minority of customers...”

This offers little comfort to the Bravo III owners baffled when they call for customer service support and are told the company knows nothing about their problems or about Bravo III corrosion problems of any kind.

One owner in Langhorne, PA, told us, “They couldn’t care less and the woman I spoke with was quite rude. She said MerCruiser has no record of problems with Bravo III drives and they wouldn’t speak with me. I tried to give her my serial numbers, so some sort of record could be filed, and she wouldn’t take them.”

He said MerCruiser eventually replaced the lower unit, “but I went through a lot, and I mean a lot, of BS to get satisfaction. It’s not like these are $50 items that need replacing every two years.”

Another owner in Jacksonville, FL, said he had to “raise hell” to get assistance under warranty.

There may be light, however dim, at the end of a very long tunnel. Now, at least someone at Mercury is focussing on Bravo III complaints. Mielke told BoatUS, “I’m continuing to work with our people to better understand the experiences that consumers are having with our products and the people who take care of them. Mercury spends a tremendous amount of resources trying to understand boaters’ needs so we can bring the right products to them via the best channels.”

For now, he says, “The defenses against corrosion are to limit the amount of the dissimilar metals — which is challenging with two stainless steel props on a Bravo III — use sacrificial anodes that corrode so other components are spared or to use counter-current to neutralize the electrolysis.”

Merc recommends using aluminum anodes on boats operated in saltwater and magnesium anodes for boats used in freshwater. Bravo IIIs are supposed to be equipped with a variety of different anodes and Merc recommends the use of a Mercathode and their version of a galvanic isolator. A common complaint is that some mechanics install inexpensive after-market zinc anodes that are not up to the challenge in either environment.

Over a year ago, Merc introduced modified lower unit components, including a chromate coated aluminum bearing carrier and extra anodes and shaft seals, apparently all in an attempt to lessen or prevent corrosion. However, replacing existing parts with these upgrades is done only at the owner’s expense.

Mercury Marine’s Mielke has offered to serve as a conduit for information between BoatUS and MerCruiser. He may be contacted at tom_mielke@mercmarine.com. Owners can also report their experiences, obtain more information and keep us up to date on MerCruiser’s response to their complaints by e-mailing the Consumer Protection Bureau at ConsumerProtection@BoatUS.com or call 703-461-2856.

The BoatUS Magazine article “Corrosion Burns I/O Owners” appeared in the November 2001 Issue and is online.