Don’t say that!
How dumb would you feel now if the meteor DID strike your house?
If the mower has electric start (again, I’ve never seen a pushmower with electric start, but it was mentioned earlier), then it has a key. If it has a key, that key disables the ignition system. You can push a car down as many hills as you like, but if the key isn’t on and it isn’t hotwired, the engine isn’t going to do any firing. As for a manual start mower, I doubt anyone in the history of lawnmowers has accidentally started one by bumping a blade, but if you’re really that safety oriented, I guess you can pull the sparkplug wire.
Rick what does pulling the cord do that turning the blade doesn’t? Doesn’t really matter, because both turn the engine, which is how one starts a engine (though you would know this).
So turn the mower over, clean the underside, move the blade to get at the area behind it and loose a hand and several fingers on the other - what’s so hard to understand.
Not sure I buy this. I’ve started a good many planes by “propping”. It’s routine to pull the prop through several cylinders with the mags off, and I’ve never heard of an engine firing when the mags were truly grounded.
If what you’re saying is to be skeptical that a spark truly can’t happen, I’ll agree. But once you’ve eliminated the chance of a spark (by one or more of several means: spark plug wire, ignition switch, etc.) you can then regard a spark-ignition
engine as tolerably safe.
I agree with Rick. For at least 15 years push lawnmowers have been required to incorporate a “grip safety” (or similar) that disables the ignition when the operator isn’t in position. The chance of such a mower starting while on its side is vanishingly small.
(I’ll concede that it’s very easy to pull the sparkplug wire, so there’s no compelling argument against doing that.)
On every mower I have looked at that is currently on the market except one, The blade and engine are locked together. The grip safety on this type mower is a BLADE BRAKE. Despite its rather misleading name a blade brake brakes the blade prevents the blade (and engine) from turning unless the griup safety is held in. The only exception to this that I have seen is either a Honda or a Torro (I don’t recall which) which has a clutch instead of a blade brake. Unless the grip safety is held in the blade is NOT CONNECTED to the engine. You could spin that son bitch till the cows come home, and it will never start, cause it is not attached to the engine.
So to sum up the engine either won’t run if the grip safety isn’t held in or if it does, it is not connected to the blade. What is so hard to understand?
If you doubt this in any way, try this simple and safe experiment. Go out to your lawn mower. DO NOT use the grip safety. Pull the rope and try and start the engine.
Report results.
No one yet has presented any plasuable reason why a modern mower needs to have the plug wire pulled to prevent it from possibly starting while on its side.
Finally, go back and read post #2 closely. Please somebody show me where I said to rotate the damn blade. I never said to rotate the blade. I have cleaned my mower many times, just like I have described here and I have never had to rotate the blade. There is enough clearance on my mower (and my previous one) that I can get my entire hand between the blade and the deck with no problem. No rotation of the blade is necessary. Bosda brought this whole thing up, by telling TKoS to disconnect the spark plug cause it might start.
Look I am all over safety when it means something. Every class I teach I talk to the students about safety. I work in a dangerous industry. Poeple lose fingers, eyes, and sometimes their lives working around engines. But the problem I have with what Bosda posted is this, if you clutter up everything with meaningless warnings, then it is much easier to overlook the truely important ones. IMHO it is better to have a few very important warnings, than a metric buttload of silly ones with a couple of very important ones buried in the middle.
Examples:
Important: Do not refuel the mower with the engine running, fire could result.
Silly: Disconnect the spark plug before turning the mower over to clean.
YMMV and
$.02
Gee, Rick. Relax a little. We don’t know how modern this mower is, and plenty of people that may read this thread have older mowers. And I myself don’t like the new ignition interrupts on new mowers and blade brakes that are supposed to protect people from their own stupidity. Many of these safety measures are a pain in the ass that common sense can over come. Some people may override them deliberately, and some may not know that they have failed.
Pulling the plug wire off is a simple precautionary measure. Remembering to put it back on before you spend an hour trying to restart it is another issue.
I have always had to spin the blade to clean under the deck of a mower.
Mowed lots of grass. Had five acres that I did as a kid at home and also all the empty lots at our family’s 230 lot mobile home park.
Sort of sounds to me like the mower is beating the grass to death, and probably pulling some out by the roots. That’s going to clog it up.
Have you tried sharpening the blade? Or get a new blade?
Yep it is. But the 40 cent micro switch or the spring that might have broken that controls it is higher. Though I agree that the odds of having a mower start while on it side is vanishingly small…… I’m a bit stunned that those that are trying to be safe, and Rick that teaches safety, would count on something that could so easily fail. When the simple act of pulling the spark plug wire would remove all doubt.
When I have to pull wheels off my plow truck. I count on the hydraulic jack, and the jack stands. AND I will slide the wheel/tire under the axle just in case.
So answer me this. If the blade brake/ignition kill was overridden or failed, how does the owner turn the mower off? Also wouldn’t this failure be instantly obvious when the grip safety was released and the engine did not stop? 
After the engine finally runs out of gas, you can still turn it over and not worry about it starting since it has no fuel.
Its just a standard safety precaution…yes modern mowers are less likely to have this problem if all the safety precautions are in place but pulling a damn spark plug wire only takes seconds.
And yes, there have been cases of older mowers being started by spinning the blade. not often, but it happens.
If the kill switch was overridden by the owner, there is no way to know. If it just failed, the mower may just die by bringing the throttle down. And I’m sure a lot of people would do just that.
Sure. To someone that knows the mower. Some people may seem this failure as a bonus.
Not sure of your point there.
Just saying, that for such a simple thing as removing the spark plug wire on mowers that you or I or others that may read this thread have no familiarity with, is not a bad idea.
I think we’re saying that we believe the failures necessary for a mower on its side to start are exceedingly rare.
You’re wise to do so: Experience shows that hydraulic jack failures aren’t rare at all. So the use of jackstands is pretty much mandatory for acceptable safety.
Commodo, pro diligo superum, pacifico!
Again I thank every participant in this, my most controversial thread yet. But the point is now academic, and I’m not sure it ever merited the slightest ill-feeling between any of us.
After descending from my roof I again approached the mower. I lost my balance as I bent over and my thumb fortuitously caught a wire, disconnecting the spark plug. Sitting on the ground, I was reminded of an old superstition, having nothing to do with mechanical science, passed down to me from my grandmother. In the flood of emotion at the sudden rush of familial memory, I unscrewed the spark plug, spit three times, and tossed it over my shoulder. Then I grabbed a spade, found the spot where the spark plug had landed, and buried the sucker, sprinkling the ground with salt.
Back at the mower I unscrewed the cap to the gas tank, and saw that it was indeed dry, as I try to leave it every time I use it even if I have to mow a path down the side of the street, which the kids walking to the bus stop seem to appreciate anyhow, or at least they reward the effort by not littering so much. Carefully, I turned the mower over to expose the underside of the blade housing. Actually, there wasn’t a lot there; nothing, at least, that came within a half-inch or so of the blade. Nonetheless, using an ordinary putty knife, I scraped away the few clots of grass I found, and since I did have to move the blade thirty degrees or so to get behind it, I saw the similarity to the manually-cranked magnetoes of history, and thanks to everyone arguing on all sides, my education with respect to things mechanical was considerably enhanced. Then I accidentally cut my left thumb off with the putty knife. Just kidding. Actually, I swabbed out the spark plug socket (which was itself very sooty), installed a new one, filled the tank with gas, replaced the spark plug cap, and it started on the fourth try. I then mowed a stretch of my neighbor’s lawn (my grass was too short for the test) and in a short time, it stalled. Throwing caution to the wind, I merely uncapped the spark plug and turned the mower over, with no salt or burying or nothin’. And I found the underside of the mower completely clean, except for the grass outlet, which was completely clogged with clippings. So the question is, why is the hole supposedly designed to let the grass OUT the very place where it gets stuck? The plastic hood, which doesn’t exactly block the opening but reduces the ultimate area the clippings can exit through, could come off, I suppose, with little risk: there aren’t rocks or other dangerous objects in my yard that could be thrown. Would that help?
Set the mower so it doesn’t cut so close to the ground.
My god… it’s full of stars!
[sup]Don’t you hate it when you make a very clever, very subtle reference, and it seems like no one picked up on it?[/sup]
Is the blade on upside-down or something? It sounds like it’s not generating enough airflow to push the clippings throught he chute. Also wash the bag. If it’s clogged with dust and dirt, the air can’t flow through it either, just like with a vacuum cleaner. Actually the latter is more likely, IMO, than the former.
With all due respect - I think that those advising against pulling the plug wire are being obstinate at this point. The issue (not the OP) is “what is a good safety procedure to follow when working on the underside of a mower.” You don’t know how old the mower is, whether it has a blade brake, whether it is electric start, whether the brake is working, etc.
Doesn’t “treat every gun like it’s loaded” apply here? I mean, if you want to work however safely on your lawn tools, that’s fine, but when giving instructions to another it’s only reasonable to include appropriate safety steps. Likewise, I don’t wear safety glasses every time I pick up a hammer, but I’d be mighty suprised to read a home handyman’s book that didn’t include that step.
There is a separate but related issue on “what is the likelihood of starting the mower when working below the deck or on the blade”. If you all want to fight some ignorance, that’s fine - and I think this has been done. With sufficient caveats, I think everyone agrees that starting a mower while cleaning the blade is pretty unlikely.
Thank you. Well said.
Actually, I think I’m being gently informed that everyone picked up on it, that twelve ham-handed references to one of the most famous movies of the modern era is crass overkill, that stupid jokes have their place on the SDMB but GQ isn’t it, and that the post burned up a lot of pixels per ha. And not only are they absolutely right, they’re being incredibly polite about it.
But I appreciate the compliment. I was happy to finally have a use for the knowledge that the inventor of the rotary mower was named Hal (well, Harold, anyhow).
Back to business. The blade hasn’t been fooled with (per the strong instruction in the manual to leave it alone) in the year the mower’s been out of the box. The carriage is already set high enough to clear everything but the grass, I mow the lawn every week, which means taking basically the top inch to inch and a half off the lawn, I haven’t bothered with a bag because I can’t even get the clippings past the chute. Looking at the lawn, the grass seems to be fairly cleanly cut with no “divots” as it were. In fact, when I eventually finish, my lawn looks (to me) much better than those of my neighbors, who tend to plow furrows, but who do it without complaint from their machines.
At any rate, the next stop is a dealer, I guess, who will probably tell me it’s being obstructed by a large chunk of packing material I forgot to remove. Again, my very sincere thanks to everyone: the problem my not be completely solved, but I’m a lot less ignorant than I was before.
[hi-jack]
Can’t let this by. On small aircraft engines that use magnetos, the mags are grounded to preventing them from providing spark. A broken switch, wire, or something corroded is all that is needed to make the mag hot.
I know three people personally who thought the mags were safely grounded, they weren’t and were actually hurt, One is dead. One has a wooden leg and one has a nasty scar.
I personally have found 15-20 hot mags on various planes that I personally was helping start by hand propping them.
I know one mechanic that almost lost his arm because he was sloppy while doing a compression check. It spun the prop and almost took his arm totally off.
I treat all props like a gun barrel, I stay where it can’t get me. I have hand propped all kinds of aircraft engines including P&W R-985’s ( Beech-18) and 1340’s on AT-6’s.
The most dangerous for me is a Lycoming I-O 540 in a Piper Comanche with a low nose strut. Lots of compression and very hard to pull through effectively without having a body part in danger.
I was an instructor at Spartan School of Aeronautics for several years, 68-70 or so and one of the problems we would normally put into the smaller test engines for the folks in ‘Test Cells’ to trouble shoot was the ‘hot mag’. It was so common an occurrence that we trained the new mechanics how to deal with it and how to prop an engine safely.
Pilots should check for ‘hot mags’ frequently but most do not, they shut down with the mixture control and so have no idea if they have a hot mag or not.
Guns and propellers are always loaded. That is the only way to play it.
YMMV
[/hi-jack]