Bravo lll Stern Drive Mystery Paint

Michael TMichael T Member Posts: 7,227 ✭✭✭✭✭
edited December 2015 in Engine Discussions

For those who like a mystery, here's a boating one. Last year when looking at my new twin Mercruiser Bravo lll X drives I nearly had a heart attack. When they arrived newly installed on my new 2014 Rinker EC 360 from the Rinker factory every surface of both drives were the glossy black Mercruiser Phantom Black color that we are all used to. However, after one summer's use the inside edges around the anti-cavitation plates of BOTH drives were a distinct gray color. I asked my tech and he had other techs look at it. No one had ever seen this color develop on a Merc drive. I asked if my drives could have been scraped or chipped at the marina and someone had touched them up. They swore - no way - "man we would have told you." I believed them. Upon closer examination it was clear that the colour had been applied with great precision and in a very professional manner. I used to own a painting company and know paint application. I had an acquaintance who used to own an exotic coatings shop. He said it was a very professional job and looked like dual or triple stage epoxies of some kind. I started calling around with no luck. Then it hit me - look at some other B lll X drives. ALL the new ones I found were glossy black, everywhere on the drive. Then I remembered that there was a 2014 Rinker 290 that had a Merc 8.2 B lll X drive combination, at our marina. It had been used for a summer. BINGO!!!!! It had the same markings as my drive. We all looked at each other and said "FACTORY". I called Mercury and never did get a "real" answer, no denial but no answer..... and I get it. I'm sure it is a special coating that Merc is guarding the technological secret of its composition and purpose. The best explanation I got was that it had to be applied to the drives of new 8.2 Magnum B lll X drives to deal with the unbelievable heat generated by the newer catalytic- converter engines. The techs showed me what they said were exhaust ports in that area (see picture number two for the "square" exhaust port) and agreed with what I was told -  that this "exotic" factory coating was to prevent the super-heated exhaust from corroding/damaging the anti-cavitation plates and that the heat had made the "gray" coating show through the original gloss black. Don't get me wrong, the coating on my drives in this area is super strong, smooth as glass and has not shown any deterioration but the clean lines where it stops and starts are so defined (as in sharp lines) and so clearly visible that it has to have been deliberately applied. That's our best guess at the mystery!


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