Why are boat motors so unreliable?

[Moto17]

Just something I thought of. Why do boat motors (particularly high performance) seem to be so unreliable compared to cars. I mean it seems every rally I go to at least one person (usually more) has some kind of issue before the weekend is over.

My theory is your car motor doesn't run at 4500+ rpm consistently. At most it may be at 2500 rpm riding down the highway. Interested to see others opinions on why this is.

[Forkin' Crazy]

main·te·nance
/ˈmānt(ə)nəns,ˈmān(t)nəns/
Learn to pronounce
noun
noun: maintenance

1.
the process of maintaining or preserving someone or something, or the state of being maintained.

[LakeFever]

Naturally aspirated SBC, BBC and most Ford so and bb engines seldom suffer severe mechanical failure, rather they tire fairly quickly in race use and require a freshen to perform at peak levels. Boost brings on a whole new level of failure concerns to the point where top fuel engines require a rebuild every single pass down the track. So it’s not to say four stroke car race motors are more reliable it’s really how heavy they are vs power output. Mopar stuff is a completely different animal and most don’t race them because of the cost vs reliability vs the performance. Juice ain’t worth the squeeze

two stroke motorcycle engines typically require a rebuild once per season if your running them
hard. I would place boat motors above these in the reliability spectrum but power to weight plus the inherent two stroke air/fuel/heat difficulties are what cause most of the troubles. Run them to extremes and the reliability goes down considerably

[mach351]

Drive your car in only second gear all day every day and see how long it lasts lol.

[SUNKIST]

if ya running an evinrude or johnson you'll find yourself broke down and repairing
a lot more often. An underwater gear case with like 8 places of possible water intrusion....is awful

[moatorbotin]

ridden hard, put away wet

[Jay Smith]

I don’t see that in engines I build , example : just rebuilt a Modified 225 Pro Max customer noticed a chirping in the upper end I over the phone tried to trouble shoot he was concerned as was I the upper bearing was failing it arrived I tore it down mikeing everything , really inspected upper bearing and race ( nothing ) I honed it installed new rings , bearings and added my upper bearing external oiling system to preserve the upper bearing integrity. The TDR Reed valves were inspected and looked new , reassembled engine , my last point of assembly is to scotch bright the hub taper and low and behold the hub was cracked causing the noise . Told customer about hub installed another good flywheel
problem solved , getting to the point the rig belonged to a guy named Mike he’s retire and fishes 1-3 times a week , motor was built 15 YEARS before , so lots to do whit who built it , use and abuse clean gas good oil and maybe lots of luck !!

Jay @ JSRE
www.jaysmithracingengines.com

[WiseCraft]

You must not drag race cars. Cause that don't last very long. haha

[TraceF3]

Outboard motors aren't really made to last...

Think about this: we put the best water/fuel separators we can find on them to keep the fuel as clean as possible right? But your car or truck runs that sheet gas right through with no problem! Made to last.

[JBS]

My merc 250 EFI has lasted 18 years .The promax is a 94 and it's been rebuilt once, still runs strong. My 50 Yamaha is 16 years old and still runs good. I take care of them and service them regularly. When I was drinking, I was lucky to get a couple of years out of them. I wrecked a few trucks and flipped a few boats too.Go figure?

[Chaz]

My merc 250 EFI has lasted 18 years .The promax is a 94 and it's been rebuilt once, still runs strong. My 50 Yamaha is 16 years old and still runs good. I take care of them and service them regularly. When I was drinking, I was lucky to get a couple of years out of them. I wrecked a few trucks and flipped a few boats too.Go figure?

That's as honest as it gets right there ....

[David]

Our outboards have been mostly bought new and kept for a long time and reliable

[CUDA]

You have a 4 month season in fresh water

No ethanol gas here I pay a little extra for marine 90 fuel, have a 500 gal tank, they screw you at the pump for marine gas, get your own tank 20 years ago I got my own tank.

Ethanol gas and carbs = problems because they don't get used often enough gas breaks down chit happens.

lots of people let boats sit long times between use and ethanol should be removed from all gas.

We all have seen the signs and stickers on gas pumps everywhere stating that there is 10% ethanol added to our gasoline. This Mixture of 90% gasoline and 10% ethanol is often referred to as E10 or “gasohol”. We usually just fill our tanks up and go not ever giving a thought to what effects burning the added ethanol in our engines may have. Does ethanol damage engines? Do you lose power, performance, and MPG with ethanol? I have been asked these questions and many more at our bike shop numerous times. In this article I will try to answer these questions and tell you how to combat ethanol related engine problems. So read on and study hard, there may be a pop quiz later.

Why is ethanol added to our fuel in the first place?

The answer to this question goes back to amendments made to the “Clean Air Act” in 1990. This amendment stated that gasoline be oxygenated to cut down on Carbon Monoxide emissions. The first additive that was used to do this was Methyl Tertiary Butyl Ether (MBTE). MBTE had a very strong turpentine smell and it turned out to be proven to contaminate ground water. Little is known about the long term health hazards from exposure to MBTE contamination in our water. MBTE had been used for this as early as 1979 in some states as a replacement for the lead in leaded gasoline, however due to MBTE polluting ground water it was replaced by ethanol around the year 2000. I worked at a small engine repair shop when MBTE was added to our gasoline. Our shop went from one full time and one full time mechanic to three mechanics working overtime to keep up with repairing damaged engines. It should be noted that gasoline with MBTE and gasoline with ethanol should not be mixed as this can cause precipitates that clog fuel filters and carburetors.
Are there positive effects of ethanol in our gasoline?

Additives like MBTE or ethanol are used as an Oxygenator in gasoline. Adding an Oxygenate like MBTE or Ethanol into gasoline reduces Carbon Monoxide emissions thus reducing pollution but this reduction in pollution is really only noticed in engines that have a carburetor and are not computer controlled by a “closed loop” EFI computer system. Any vehicle that has Electronic Fuel Injection (EFI) uses at least one oxygen sensor to analyze the exhaust allowing the vehicle’s computer to make adjustments to control emissions so they benefit very little from an ethanol mixed fuel as far as an emissions reduction goes. The main reason ethanol stems from the Bush administration’s push to reduce America’s dependency on foreign oil so the result is 10% ethanol is added to dilute gasoline to cut down on the amount of gasoline consumed to reducing the amount of foreign oil consumed.
What are the negative effects of using ethanol in our engines?

There are five major problems that I know of from ethanol in our gasoline;

1. Debris in fuel / premature fuel breakdown. It is almost impossible to empty all of the fuel from any engine system so there is always old fuel somewhere in any fuel system. Straight gasoline starts to deteriorate around 30-60 days and ethanol fuels break down even faster than straight gasoline. When gasoline breaks down leaving gum and varnish in fuel tanks, fuel lines, carburetors, etc. Ethanol is also a great cleaner of gums, varnishes, dirt and the rust that water in the fuel creates. That is why ethanol is used in almost every bottle of carb / injector cleaner on the market. So when you fill up your tank you introduce fresh ethanol to run through your fuel system and it will dissolve the deposits running all that crud through the engine’s fuel system clogging fuel filters, injectors, and carburetors. Clogged fuel filters will drop fuel pressures telling the regulator to work the electric fuel pump harder to keep the fuel pressure up. This will burn out fuel pumps. Gummed up carburetors and fuel injectors all lead to poor performance and all of this leads to hefty repair bills. Considering you never really know how long the E10 sits at the refinery in a holding tank before it gets transported to the pump station to sit in the underground storage tank just to be purchased by you to sit in your tank before being burned in the engine, break down of the E10 gasohol fuel can be a real issue.
2. Water in fuel. Pure gasoline does not absorb water but ethanol will. Ethanol is hydrophilic this means that it pulls moisture from the air and bonds with it. In ideal conditions E10 gasohol will keep roughly .5% water by volume is suspended in gasoline. Our fuel tanks and fuel storage cans are hardly ideal conditions as they need to be vented allowing the ethanol to absorb more moisture from the atmosphere or in the form of condensation. Ethanol never truly bonds with gasoline molecules it is a loose mixture at best so when the threshold of .5% water is exceeded or the E10 gasohol mixture cools off every night the water / ethanol solution falls out of suspension in the gasoline. Oil and gasoline float on water as they are lighter than water so the water /ethanol mixture will stay at the bottom of your fuel tank. The process of the water and ethanol separating from the gasoline and sinking to the bottom is called “Phase Separation”. Phase Separation is a real problem because the water from the bottom of the tank is sucked up and sent to the engine it causes a lean condition raising the engine temperature causing valve damage, carburetor, fuel lines and electronic fuel injection pumps pull fuel from the bottom of the tanks where the ethanol / water mix stays and water doesn’t burn well in the engine leading to premature engine / fuel system corrosion and poor engine performance. It gets worse, ethanol and water mix in E10 gasoline is a breeding ground for microbes like bacteria and fungi which just adds to the corrosion and debris in your fuel system.
3. Loss of power, octane rating, performance and mileage from E10 gasohol. Contrary to what most people believe, higher octane gas does not make your engine more powerful. Only if your engine is built for performance or racing with a higher compression rating do you will need to use a higher octane gasoline. Your vehicle manufacturer tells you what octane rating to use depending on your vehicle’s requirements. This information can be found in the vehicle owner’s manual, on the fuel door or gas cap. At the pump you typically have three choices of octane ratings use gasoline that has an octane ratings from 87 (lowest), 89 (midgrade), and 91 or 92 (premium) this is due to a few factors, but it is mainly relevant to the compression rating of your engine. The higher the compression the higher the octane required. This is due to the fact that gasoline and air mixture heats up as the piston moves on the compression stroke gasoline will ignite before the spark plug fires. This is called pre-ignition and it will damage the engine. Octane prevents this by slowing down the burn rate from an early damaging explosion to a slower more controlled burn. Pure ethanol has an octane rating of 113, so adding ethanol will raise the octane rating of gasoline. The gasoline blender has to take this into consideration and uses a lower octane base gasoline so when the ethanol is added you don’t get a higher octane fuel. Now what happens is this; you purchase E10 gasohol with an octane rating of 87, phase separation occurs and as the ethanol sinks to the bottom of the tank the octane rating in the gasoline actually gets lowered to around 82 to 84. This is too low for a gasoline powered engine to run efficiently and causes loss of power and engine damaging pre-ignition. Ethanol produces about 34% less energy than the same amount one gallon of gasoline so in an E10 mixture you will lose 3% – 5% of your horse power and MPG.
4. Ethanol is corrosive. Ethanol is an excellent solvent and will clean all of the gunk and grime that an engine will accumulate but these same strong cleaning qualities can lead to trouble for your engine. As I had stated earlier in this article ethanol is a great cleaner and this alone can cause issues as it dislodges built up dirt sending harmful and filter clogging particles through your fuel system and engine. Ethanol is also a drying agent and can disintegrate plastic, rubber, some types of fiber glass, aluminum and magnesium. Ethanol is most corrosive to ferrous metals (metals that contain iron, such as steel). This corrosion leaves behind salt deposits and a jelly like substance, both of which can clog fuel filters, fuel pumps and carburetors. Ethanol also burns at a higher temperature than gasoline causing damage to pistons. Any car or truck that is not a “Flex Fuel” vehicle is most likely not equipped with ethanol resistant parts and even less small engines like lawn mowers; motorcycles etc. are equipped with ethanol resistant parts. Marine motors and ethanol just do not get along at all due to the high water content in their operating environment. Due to the high damage rate and risk of marine motors developing polluting gasohol leaks from ethanol damage, a lot of marinas are currently offering ethanol free gasoline. According to the FAA ethanol is forbidden in airplane fuels (excluding air craft licensed as experimental). Using E10 in 2 cycle outdoor power equipment (weed whackers, chainsaws, etc.) can seize motors and most manufacturers will not honor warranties on their equipment if E10 is used. E10 is bad enough, but if E15 is put into place we can expect severe damage to any vehicle not equipped like an E85 Flex Fuel vehicle. Please consider that the levels of ethanol are not closely monitored by most gas stations, but you can purchase inexpensive ethanol test kits to be sure the ethanol percentage is not over 10%.

[jpf091959]

I have great luck with outboards. I used to run big block car motors, run them one hour and work on them for two.

The new outboard are like high performance motorcycles, run the hard and they idle right down and can't be broke.

[perfmarine1]

Just something I thought of. Why do boat motors (particularly high performance) seem to be so unreliable compared to cars. I mean it seems every rally I go to at least one person (usually more) has some kind of issue before the weekend is over.

My theory is your car motor doesn't run at 4500+ rpm consistently. At most it may be at 2500 rpm riding down the highway. Interested to see others opinions on why this is.

That is because they all run Mercury, and beat the crap out of them seeing how fast they will go every run. I still run 1984 Evinrudes and never have a issue, I can't remember the last time I had the cover off. 10-12 years ago maybe.

Sorry I could not help myself!!!!!!!!!!! LOL