Boating Magazine - 22 Ways to Screw Up Your Engine
By David Seidman
Ignorance Isn't Bliss, It's Expensive.
Think you know how to keep your engine
going? Well, you might. You probably filter the fuel,
change the oil, and make sure the cooling water is
flowing. And of course you've read the engine manual. Or
have you? I'm betting there are lots of things you've
missed in that little bible, and that once you got past
Page 7, you only looked at the pictures. Too bad, because
even though you think you know what you're doing, you
might be screwing up your engine by doing dumb things
Economic Indicators Ignore an idiot
light or warning buzzer once it comes on and risk a
whopping repair bill. But sunlight can overwhelm LED or
low-watt bulbs in indicators, making them hard to see.
Solution? Provide shade, or move them. Even better are
warning buzzers. But can you hear yours over the engine,
stereo, and wind? At high speeds, noise levels can be in
the 95+ dB-A range (like standing in a New York City
subway station). Can your audible alarm top that? To be
sure, install a Screamer 110 dB-A sounder for $8
(www.kitsrus.com). But keep in mind that by the time a
warning goes off, the problem has already occurred. We
like items such as Caterpillar's in-line water flow
sensor that triggers an alarm when cooling water
slows-well before overheating begins.
In Hot Water
Install your thermostat backward so the heat-sensing part
is located on the wrong side. This is a surefire way to
guarantee your engine overheats. It's such an easy
mistake, even the pros do it.
You Never Listen to Me Turn a deaf ear
to your boat. A sound that imitates a squealing pig
probably means a belt is loose. A metallic tapping that
keeps time with engine rpm means your valves, lifters, or
rocker arms are in trouble. Grinding and grating metal
could mean a water pump bearing is shot. If your exhaust
gets louder and has a higher pitch, there's probably less
cooling water running through it-check the water pump.
The cacophony is music to a mechanic's banker.
Don't Look Down Disregard engine gauges
at your own expense. Airplane pilots are taught to
regularly scan their gauges. They start at one side of
the panel and pan slowly across, looking at everything,
and then pan back the other way. With only a few gauges
on a boat, this pan and scan shouldn't be a big deal.
Some owners turn their gauges so the needles point up, to
high noon, when running normal. It looks odd, but it's
easier to recognize when a change occurs.
Antifreeze Meltdown Use straight
antifreeze instead of topping off your sealed cooling
system with a mixture of antifreeze and water. More is
better, right? Wrong! The closer the mixture in your
cooling system gets to pure antifreeze, the hotter the
engine will run. Undiluted antifreeze boils at a higher
temperature (about 230 degrees Fahrenheit) than water
(212 degrees Fahrenheit). It therefore retains more heat,
allowing the engine to run hotter or even overheat.
Turn Up Your Nose Smell the fresh sea
air and ignore the engine room's funk. A healthy engine
has a distinctive odor. Take a whiff and remember it.
Then when an odorous messenger shows up, you'll know
something's wrong. The acrid stench of burnt rubber could
come from a dry-running water pump impeller (look for a
clogged water intake), not enough cooling water reaching
the exhaust, a slipping V-belt, or a failed coupler in
the stern drive. A hint of burnt oil might mean the
engine was run hard, or if it's a strong odor, there's an
oil leak dripping on the hot engine. A cloying sweet
aroma indicates leaking antifreeze. And a smell like
burnt hair could be an electrical short.
Running Dry Fire up the engine while
it's on the trailer to make sure it'll start. You figure
that in those few seconds the engine won't overheat.
You're right, too. But the water pump's impeller can get
damaged. Impellers need water for lubrication. Without
it, they wear away or just fail completely.
Cheap Oil Feed your two-stroke outboard
bargain oil and ensure rapid aging. Don't think you're
saving money when you buy some off-brand oil. To meet
industry standards, oil has to pass the test only once,
meaning it's not monitored by the batch. Better oils are
uniform, consistently meeting the standard case after
case. During the average summer, a 100-hp engine may burn
only a gallon or two of oil. The difference between cheap
oils and the ones offered by engine manufacturers may be
about $10. Remember: The most expensive thing you can put
in an engine is cheap oil.
First Coarse Assume new filter elements
are doing their job. Diesel engines, and gasoline engines
running far offshore, should have two water
separator/filters per engine. But don't put the same type
of element in both filters, or worse, put the finer
element in the first filter. Doing so makes that filter
do all the work, with little to no benefit from the
other. Put a coarse (30-micron) element in the first and
a finer (2-micron) in the second. This way both share the
load, do a better job, and give you longer element (and
Shakedown Engines will always vibrate,
so you learn to ignore it. If your bowrail starts to
shake each time the boat climbs on plane, but you don't
feel it at the helm, it's likely that one or more of your
prop's blades are bent. A vibration only at certain rpm
could mean your prop needs balancing. When the whole boat
rumbles and shakes at all speeds, the engine and shaft
are out of alignment. If you want to see how and when
your boat vibrates, watch the surface of a bucket of
water placed in the cockpit.
Jets Suck Water jets let you run in
shallow water, so you go in freely. Unfortunately, you
may not come back out. Jets use some of the water they
suck in for cooling. If that water has sand, muck, or
rocks mixed in, your cooling system may get clogged. One
jet drive manufacturer goes so far as to warn:
Avoid shallow-water conditions. Continuing
with, Always be in at least two to three feet of
water, especially when accelerating from idle
speeds. If you must run in skinny water, go fast.
This way the jet sucks in cleaner surface water as the
boat rides high and well above the bottom.
Forget to Flush Put your jet drive away
after each use without thoroughly flushing the engine and
you may have to put it away permanently. Although it may
not ingest something large enough to cripple it while
underway, it can develop a slow buildup of crud. Clean
out internal passages by flushing your jet with
freshwater for 10 minutes, and use plenty of pressure.
All current models have a flushing port. Older Mercury
jets can be updated with an accessory flushing attachment
that costs about $25.
Last Gasp Rev your engine before turning
it off. It was probably a mechanic needing work who
started this myth. The idea is that it's supposed to make
the engine easier to restart. But all it does is leave
unburned fuel coating the cylinders, which forms a gummy
Flick the Switch Turn the battery
selector switch incorrectly while the engine is running
and, bam! No more alternator. When switching from 1 to 2
or Both, never pass through the Off position. For the
microsecond the switch is completely closed, the
alternator's output has nowhere to go. This will blow out
the diode and kill the alternator. Prevent this with a
$13 gadget called Zap-Stop. It automatically directs any
charge over 16 volts to ground.
Anode Ignorance Sacrificial zinc alloy
blocks go only on your drive or propshaft, right? Wrong.
Your engine has an internal one, too. You'd better find
out where it is and learn to replace it every time you
change your oil. If left in place too long, it will start
to crumble and give off particles that may clog your
Stainless Steal Assume that if the ring
of a hose clamp is stainless, the spiral screw that
tightens is made of the same stuff. Often the screw is
mild steel, which rusts if you put a salt shaker near it.
A broken hose clamp is a sure way to lose water, fuel, or
an exhaust hose-or to sink a boat.
Dangle a Line Leave lines hanging off
the stern. Wrap some 3?8" nylon around your prop at
a few thousand rpm and bearings get shot, drip glands rip
up, transmission gears strip, and if the engine mounts
are weak, the engine pulls out of alignment or loosens
from its bed.
Neglect Corrosion Ignore your engine's
need for a dry environment. Keep electrical connectors
coated with WD-40 or Vaseline to repel moisture. If
boating in saltwater, occasionally wipe down the engine
with a rag damp from freshwater. Make sure you get rid of
all dried-on salt crystals, which attract moisture. Wipe
dry, spray on a light coating of oil, and spread that oil
around to make sure all parts (even undersides) get
Don't Change Don't change your oil-just
dilute what's been left behind. Your goal is to
completely replace the old oil with new. Compare how much
oil comes out with what goes in. The difference is the
amount of foul oil left behind. If you can't suck out all
the old oil from the top, install an oil draining kit
under the sump. Just make sure the engine's mounting
angle allows oil to collect over the drain plug. Or,
change your oil more frequently so that the oil left
behind never has a chance to get bad.
With This Ring Purchase the cheapest
fuel-'round here we call it frog wizz. You
will not only get the worst possible performance but
you'll likely destroy pistons, rings, and cylinders. Your
engine's manufacturer specifies a minimum octane rating.
Go lower and your engine may knock or ping under load. It
can put up with this for a while, but do it for too many
tankfuls and carbon can build up in the piston ring's
grooves and behind the rings. This forces
(jacks) the rings outward, scoring the
cylinder or, worse, locking up the engine. While almost
anything will run some of the smaller outboards (rated
for as low as 84 octane), most engines require at least
an honest 87 octane, with 89 preferred. For
high-performance models, use 91 octane.
In Bearings We Thrust Replace a prop on
an outboard or stern drive and forget to put the thrust
bearing back on first. Or if you have a few lying around,
put on the wrong one. Without this washer-like bearing,
the prop's hub rides hard against the gearcase each time
you shift into forward. Check the price of a gearcase
housing and you'll never forget your thrust bearing
Ultimate Screw-up Don't read the
instructions. I used to write these neglected pieces of
literature and accepted that most people ignore them. Too
bad, because our lives would be a lot easier, and our
engines would last a lot longer, if we only took the time
to refer to them every once in a while. As one
manufacture put it, The only thing we like to see
wear out is the owner's manual.