All of the storage instructions I have seen for small engines, such
lawnmowers, say to take out the spark plug and put in a couple
of oil, and pull it thru a couple times, then replace the spark plug.
I have done that for several decades without a problem. But
occurred to me.
Why can't we just tilt the mower so that the spark plug is pointed
(easy for vertical shaft engines) and then just pull it thru a couple
It seems to me that the oil will run over the bottom of the piston
when the unit is pulled thru a couple times, the oil will wipe the
of the cylinder, accomplishing the same thing as when we squirted
oil into the top of the cylinder....
I would like to hear any opinions on this. Perhaps there is
missed, but this would save a little trouble , and could easily be done
after each mowing operation.....
Andy in Eureka, Texas
I suspect that over a short period of time virtually no oil
would get past the rings, so there'd be no effect at all.
On the other hand, over a long period of time sufficient oil
might get past the ring splits, but wouldn't serve any purpose
other than drowning the plug.
The crankcase has to be vented so it does not build up pressure from the
small amount of blow-by that gets past the rings. This vent is part of
the valve cover on a side valve engine (most of the small engines out
there.) There is a tube or hose that connect this vent to the intake so
as to actually create a slight vacuum in the crankcase when the engine
is running. When you tip the engine the wrong way the oil flows pretty
freely through the vent and then into the intake. Once there it is a
major nuisance. It can saturate the air filter, get into the carb and
even leak past the intake valve into the cylinder. While this might be
good for storage purposes, it's going to be a mess when it's time to get
it running again.
If the engine in the mower is in any kind of (good ) shape, no oil will flow
past the piston rings.
And only a small mower could be tilted as you suggest by a man of average
Removing the spark plug and introducing a small quantity of oil is a mundane
But none of this is required after each mowing- only for storage over
My thanks to all those who ventured a reply here.
I'd like to comment on Chas's reply, which is typical of those who
had reservations on this method.
When you put oil in the spark plug hole, only two things get
lubricated - 1) Part of the top of the piston and 2) The part of the
cylinder where the rings actually wipe. The rest of the inside of the
top of the cylinder stays as it was, since there is nothing to wipe the
oil over it AND the quantity of oil isn't large enough to slosh ( for
Wiping the rings coats that part of the cylinder since THAT PART is
the part that has wear 6 months later when you crank it up for the
spring. Having a little film of oil on that small part of the cylinder
helps reduce the excessive wear that dry piston rings have on a dry
cylinder wall. Remember how the engine lays and where the oil
reservoir lies..... Most of the cylinder does not normally anywhere
near the oil, and that's OK, since there is no rubbing action on that
part of the cylinder....
Also, oiling thru a spark plug hole works much better on an
engine whose cylinder is vertical, since the oil will distribute itself
all over the top of the piston before wiping. On a vertical shaft
engine where the piston is horizontal, only the bottom of the cylinder
will be wiped UNLESS you tilt the mower to make the spark plug on
top...... Same tilting action as I proposed for the internal wipe,
upside down....... Yall gotta think about what happens inside the
So, in my opinion, it doesn't matter whether the piston rings wipe
the ring area from the bottom or from the top.
Regarding the strength to tilt the lawnmore and pull the cord
two or three times ---- well, it just never gave me a second thought.
I would think that if such strength were lacking in the actor, that
would be paying someone to mow their yard anyway :>))))
Regarding pouring oil out the crankcase breather tube ---
it doesn't happen in the 3-4 second the mower is tilted. Heck,
I tilt the mower longer than that when I'm mowing.... I've never
seen it happen..... And , for this operation, there is no internal
pressure buildup to vent, to speak of....
Ok, thanks again everyone. I welcome criticism of my understanding
of the inside of a mower. There's a lot of guys here I can learn from.
Andy in Eureka, Texas
On a somewhat related side issue, I do believe it's worthwhile,
when putting away a small engine, to pull gently on the starter
until you feel compression resistance, and leave it that way, with
the valves closed.
Gravity takes the oil to the lowest part of the cylinder. Condensation
will also head for that same area. You want the oil to get there first
to provide a barrier.
Most small engines have a small plastic oil slinger in them that begin
slinging oil as soon as you attempt to start it. The storage oil is more
to protect from rust or corrosion that can cause stuck rings from
moisture than as a pre-lube to reduce wear.
In the cases of stuck rings that I have seen most were caused by carbon.
The rest were caused by rust or corrosion and always at the bottom of the
3-4 seconds is not going to do anything. I would guess (and it's only a
guess) it would require more like a minute or longer to allow any oil to
leak past the rings.
If you tip the mower with the crankcase breather down for long, while it
is running it will start sucking oil through the breather and smoking
There is no internal pressure buildup ever. While it is running there is
If you are going to do this then I suggest you locate the valve breather
and make sure it is kept as near the top as possible while tipping.
Maybe even remove the plug just to see how long it does take for some
oil to come out of the plug hole. If you do that, let us know how long
it took. I am curious.
As an aside, I stored a boat motor for a couple months with the
tilted too far toward the plug, and the space in the cylinder filled up
oil from leakage. When I tried to crank it, the oil would not let the
go all the way. It felt like the engine had seized. Really felt like
clunk metal thing..... As a last resort I pulled the plug to see if I
tell anything and the oil ran right out. I put the plug back , and the
problem disappeared, tho it did smoke like hell for a couple
So now I always store the boat motor with the engine tilted so that
it can't leak past the rings into the cylinder head....
Just thought I'd mention it.... I was very pleased with myself when
the problem went away :>)))))
Andy in Eureka, Texas
just something about the way you said "pleased" has
prompted me to share these pictures from my web page
concerning a recently completed repair that I'm really
really really pleased with the outcome of.
I gave consideration to doing just that. after a short
conversation with my bank account I realized the 30 dollar
salvageable salvage yard manifold would make do.
that drill bit saved me many hours of getting the head off
and then putting the head back on as well as the cost of all
the required gaskets and then the service cost at the machine
shop. interesting operational aspect about that bit was, it
grinds instead of cutting. to make it work you need to be
turning the bit at least 1000 rpm and you got to push with
substantial force. doing that to a conventional high speed
steel bit will burn the edge and tip right off of the bit.
best 2U Eggs,
yep :) headers do make a nice sound. increased HP output
would have been my main reason for spending the extra money.
maybe next year there will be adequate funding available for
on their web page they use the words "For Rotary or
Percussion Drilling" I wonder if Percussion Drilling
is another way to say hammer drilling?
have a good day Eggs,
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