Owning a 2004 Mercury 115 FOURSTROKE

[MisChief15]

I just bought a boat that is powered by a 2004 Mercury 115-HP four-stroke-power-cycle, electrically-operated fuel induction, saltwater-series engine with about 300-hours running time. I have never had a Mercury before. The seller has shown me receipts for service in the prior 12-months for oil [change], and filters, sacrificial anodes, and water pump impeller changes. I am happy with that.

I have owned mostly Yamaha engines.

[Moderator's note: a survey question that asked if at any time has anyone ever owned a 2004 Mercury 115-HP engine was removed because the answer is quite obvious--yes, certainly someone has owned that engine, for example, the guy you bought the boat from. Please do not ask survey questions. If you have a specific question you want to ask about this engine, please do just that.]

[jimh]

I have owned mostly Yamaha engines.

I think you are going to own another Yamaha. Here is a bit of background.

In that epoch, c.2004, Mercury was unable to manufacture any four-stroke-power-cycle engines other than a 25-HP engine which had co-developed in a partnership with Yamaha, or their then just-introduced line of V6, supercharged, VERADO FOURSTROKE engines.

At that time four-stroke-power-cycle engines were becoming very popular with boaters as replacements for the classic two-stroke-power-cycle outboard engines, and Mercury wanted to be able to offer four-stroke-power-cycle engines in popular horsepower ranges. They began to purchase four-stroke-power-cycle outboard engine power heads from Yamaha, which were typically painted black but in some cases there have been reports of the power head remained in the familiar Yamaha blue-gray color under the black cowling.

Mercury was purchasing four-stroke power heads from Yamaha for their 75, 90, and 115-HP four-stroke engines. These power heads were not part of any "co-development" venture. They were entirely Yamaha power heads made in Japan. Mercury added simple throttle body fuel-injection to them, their own midsection, lower unit, and cowling, and created wiring harnesses that would mate with existing Mercury electrical remote controls and gauges.

Until Mercury began production in Fond du Lac of the new VERADO engine, the only complete four-stroke-power-cycle power head produced domestically by Mercury was a 25-HP model.

At about the same time, Brunswick brought to the United States International Trade Commission a complaint about importation of four-stroke-power-cycle engines into the USA from Japan, and wanted the USITC to impose a tariff on them in order to prevent "unfair" competition based on lower pricing.

The hearings that ensued before the USITC were quite embarrassing for Brunswick. Mercury dealers testified that boaters preferred the Yamaha four-stroke-power-cycle engines over Mercury two-stroke-power-cycle engines (like their OptiMax engines) due to their superior performance, and that the price was not a factor in the preference.

Eventually the USITC dismissed Brunswick's complaint, citing in part that Brunswick itself was one of the largest importers of four-stroke-power-cycle engines from Japan because it was buying them from Yamaha and Tohatsu and rebranding them as Mercury.

After this rather odd series of events in which Brunswick turned on its major supplier Yamaha, the folks at Yamaha started playing hardball, and began to stop providing Yamaha power heads to Mercury to be rebranded as Mercury engines. Because there was a contract in place between Brunswick and Yamaha that required Yamaha to provide these engines, Mercury eventually got Yamaha to comply and to continue to ship Yamaha power heads to Brunswick to be turned into Mercury-branded engines for the remainder of the term specified in the contract. After that, Yamaha stopped selling engines to Mercury.

Boaters were very aware of all of this, and the terms YamaMerc or MercAha were created to describe the engine being marketed as Mercury engines that contained Yamaha four-stroke-power-cycle power heads.

[jimh]

Regarding the water pump impeller used by Mercury in that epoch: check for the recommended service interval for replacement of the impeller. As I recall, it might have been an annual recommended procedure.

[MisChief15]

Thank you very much Jim for your insight of engine series, i feel somewhat more confident about this outboard :)

[fno]

The impeller will be a Mercury product. That series of engines the powerhead only was Yamaha. The middle section and lower unit are pure Mercury. If you need an oil filter, buy a Yamaha oil filter for about $10 less than Mercury charges. Impellers are going to come from Mercury though