CONTINUOUSWAVE

Q1: are there common problems that occur frequently with four-stroke-power-cycle outboard engines?

Q2: what problems can occur with four-stroke-power-cycle outboard engines?

Q3: with proper routine maintenance, how many hours of operation should occur before the first problem occurs with a four-stroke-power-cycle outboard engine?


BACK STORY
I have never owned a four-stroke-power-cycle outboard engine, and I have not been aboard many boats that are powered by a four-stroke-power-cycle engine.

I have owned two-stroke-power-cycle engines made by Evinrude, Johnson, Mercury, two-stroke-power-cycle engine. I have owned E-TEC outboard engines. I do not know the exact number of hours of running time on those engines. The reliability of those engines was "pretty reliable."

The three Johnson outboard engines I owned always had problems.

I owned one Mercury outboard engines; it had problems with the power head--I do not recall the specific problems.

I have removed a 1986 Evinrude 150-HP that is old but has never had problems.

I plan to buy a 150-HP four-stroke-power-cycle engine to replace the 1986 Evinrude 150-HP engine.

In general four strokes are far more reliable than are two strokes and more fuel efficient while emitting fewer harmful emissions. The downside is that they are heavier. For the most part, they require annual maintenance and it may require a dealer depending on the owners DIY qualifications.

If your engine is running well with no problems I would not replace it until an expensive repair is needed unless cost is not a problem and you are tired of smelling the engines exhaust.

Palomino wrote:Q1: are there common problems that occur frequently with four-stroke-power-cycle outboard engines?

The common problems with four-stroke-power-cycle engines are:

• they need frequent oil changes, and replacement of the oil filter, which can be a messy job to perform in the water with risk of pollution from oil getting into the water;
• they tend to be heavier than two-stroke-power-cycle engines, although the latest generation of four-stroke-power-cycle engines have decreased in weight somewhat;
• they tend to need to be able to accelerate into the upper range of their power band in order to produce their rated horsepower, which creates a rather narrow power band compared to the two-stroke-power-cycle outboard engines;
• recently there has been a limited supply of new four-stroke-engines, with most available engines committed to boat builders with partnership relationships with the engine maker or actual subsidiary companies of the engine maker, creating a very limited supply available to be sold as a loose engine for a re-power installation;
• for some models their emission certification is not sufficient to be available for sale in certain states or be legal to use on certain bodies of water with restrictions of exhaust gas emissions.

Palomino wrote:Q2: what problems can occur with four-stroke-power-cycle outboard engines?

Four-stroke-power-cycle engines can have all the same problems of a two-stroke-power-cycle, and because they have multiple valves and often multiple camshafts, those components could also have problems.

Palomino wrote:Q3: with proper routine maintenance, how many hours of operation should occur before the first problem occurs with a four-stroke-power-cycle outboard engine?

This question requires a great deal of speculation and also ignores all of the factors related to the engine use, its environment, and maintenance.

Any engine used in accordance with the manufacturer's limits, which is kept clean and given the recommended maintenance, which is in a typical duty cycle of engine speed where the majority of the time the engine is at idle speeds or below 1,000-RPM and full-throttle operation is perhaps one-percent of the operating time, which is rigged with a properly sized propeller to match the load imposed on the engine, which is operated in suitable clean, debris-free water and particularly NOT in tropical saltwater, and connected properly to its associated cranking battery, should be able to deliver at least 100-hour or one-year before the first "problem" occurs, where "problem" means the owner has to take some action (like changing the oil and the oil filter or replacing the water pump wear parts) to prevent damage to the engine.

With careful use and proper upkeep, a modern outboard engine should give 1,000-hours of service, but during that time may require replacement of certain wear parts on a scheduled or as needed=basis.

Note that modern outboard engines are now sold with factory warranty protection against occurrences of defects in the original manufacturing of the engine for a period of several years, and often on purchases made during promotional periods, for periods of five, six, or even more years.

Not mentioned so far, but perhaps the biggest problem with new four-stroke-power-cycle engines: their very significant high cost.