Just bought a new Toro Lawnmower (self propelled)
Have about 1/4 acre of grass, which I expect I'll be mowing about once a
week in July and Aug.
How often should I consider replacing the spark plug ?
Once per season, or... ?
Wouldn't really want to wait until there is some sign that it needs it;
would rather do it on a
preventative maintence concept, before it really needs it. What's
Also, the same question for a 2-cycle engine weed wacker.
How often do you think for this gadget ?
Maybe every 10 years or so. The one time I did replace the plug, it was no
better starting as the engine was just worn out. Bought a new mower and it
is on the same plug at about year 7. Starts on one pul. Lov e that John
Maybe every 5 or 6 years, but if you clean it, probably 10/
My 9 year old Sears Craftsman mower is on its original plug. Starts
first pull every time, except the first use of the season when it may
take three pulls to ignite the stale gas that's been sitting in the
tank all winter :-).
You're likely to get a lot of responses like Dan gave
you, and they're occasionally true, but ... they also
operate at less than optimum power and efficiency.
Per season is a good, "safe" interval which should
keep your machine running reasonably well. How much or
how fast plugs become damaged depend on a a lot of
things such as design, how hard it's asked to work,
ambient temperatures, speeds used, carburation, storage
methods, and so on.
They're not expensive and if you're willing, you
won't be sorry for doing it once a year.
Assuming a 4 cycle engine:
The manuals usually recommend each season too. Well,
it can't hurt, that's for sure, and if a plug goes
resistive or starts to crack, you're not likely to ever
notice it that way.
I used to do it every other season, on the even
numbered years since we have a pretty short season here
in upstate NY. I made that decision one day when I was
in Florida and came across the exact same mower I had,
and it still only recommended yearly changes <g>. I
was younger in those days and had less time, so I
switched to every two years.
Nowadays I go three years or so, but each season I
pull the plugs and do a visual for wear, clean and
regap them. Once in awhile after particularly harsh
cutting season I'll see a little electrode wear, and
that plug gets replaced. Usually the gaps are off a
touch, but never much, so that's just a touchup.
It's pretty easy to learn to do if you are at all
mechanically inclined or interested.
It's always a good idea to also check that it idles
and runs at full speed OK, and goes from idle to max
and max back to idle smoothly. If not, there are some
easy adjustments on the carb that can be made too. The
manuals are usually pretty good about explaining how to
do that as the amount of adjustments possible vary,
especially on the newer engines. Some even have no
The most important thing is to keep the oil level
right and change it on schedules. I mow about an acre
all summer, and the full 5 acres twice a summer,
depending on what's going on that summer. I change the
oil about midseason and do a good lube and oil change,
sharpen the blades, check the fuel filter, etc. prior
to storing the equipment for the winter. That way
it's about ready to go next season.
I also keep a set of plugs handy for "just in case"
As for weed eaters, it's probably best to change the
plug each season; I do, anyway. They're usually 2
cycle engines and those seem to be harder on plugs than
the 4 cycles, assuming you keep the gas/oil mix right.
The manual/s won't lead you wrong. I presently have a
1979 rotary push mower, a 1985 weed eater, a 1990 and a
2002 lawn tractor, , 24 and 48 inch cut, 10 and 20 HP
respectively. Now if I could just figure out how to
get the bodies of the lawn tractors to quit rotthing
away, I'd be all set. The engines last fine, but
keeping those damned decks from trashing themselves
seems to be an impossibility.
I sold the engine from my old 1983 mower for $100
finally, when the deck was too shot to hold the
bearings/pulleys for the belts any longer. I used the
deck pulleys to make a blade-balancing stand for
sharpening blades, the wheels for a homemade wagon, and
the ammeter for my battery charger. I"ve still got the
transaxle, but I think a kid down the road wants that
this summer. The blades are hung up as souvenirs and
the rest of the body's sitting out in a tree line now,
finishing up rusting. Yes, we live in the country;
very country in fact.
About as often as you change engines, in fact. With aluminum or
magnesium (chainsaw) threads, you're probably as likely to do harm as
good by obsessively changing plugs.
1. Keep the fuel fresh
2. Change the oil regularly
3. Exercise the engines
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