# lawnmower problem



## david-david (Feb 24, 2013)

Hi guys, I'm guessing there's a few gardeners on here who nay know about this sort of thing. 

Yamaha YLM self propelled mower has started leaving clumps of cut grass on the lawn. It's cutting but isn't chucking it into the grass box.

Any ideas?


----------



## erneboy (Feb 8, 2007)

Not familiar with your model, so my comments are generic but will apply to any rotary mower with collection.

Dirty chute or underside of deck causing the grass to stick and ball up, blade damaged or worn where it generates the breeze to chuck the grass, revs too low, wet grass.

Assuming the last three are OK clean the underside and the chute where the grass should exit.

Edit: Presumably it has a kind of door arrangement which is open when the bag's attached and closed when it's not. Is the door opening?


----------



## dalspa (Jul 1, 2008)

I'm with Alan on this one. I always turn my mower on its side (watch out for petrol spillage) at the end of each season and scrape the underside clean of all caked on crud. The cuttings then have a clear route to the bag.

DavidL


----------



## david-david (Feb 24, 2013)

Thanks guys. I'll try cleaning the underside and chute. 

Erneboy - its a hard plastic box on the back and the opening is just a square hole. There doesn't seem to be a trap door or anything else that opens or closes.

What actually happens when its cutting the grass? Is it the little fins at the end of the cutting blade that chuck the grass into the box or is it like a vacuum cleaner where the motor creates suction or something??

Never thought about how a lawnmower works before and its left me puzzled!


----------



## erneboy (Feb 8, 2007)

It's raised edges or curves on the blades that do it so revs play a part too. Only large machines generally for professional use tend to have separate fans.

Take the plug lead off before investigating.

Anything under there which would prevent a good circular breeze being generated would reduce the function. There are sometimes guides around the edges of the deck on the underside too, check if there are any and that they're not damaged or holed. Pretty much anything which would prevent the generation of the breeze or cause the airborne grass to snag can have a detrimental effect.

Assuming no damage a good scrape clean will probably fix it. Give the way in to the box a clean too otherwise it may tend to become clogged at the entrance and not fill well.

Odd there's no door, or perhaps the machine will only run with the grass box in place?


----------



## dghr272 (Jun 14, 2012)

Mine is similar to yours, its rotating blades doesn't have fins, the rotating blades act like a fan and create the air pressure that directs the grass through the square exit into a plastic collection box. If I don't keep the small vents in the box clear I get the issues that you are having, I use a stiff deck brush to keep the vents clear.

Terry


----------



## david-david (Feb 24, 2013)

Thanks guys, I'll do everything mentioned and report back. 

Thats another goos Terry, didn't think about cleaning the little vent holes in the grass box. It makes a bit more sense now as to why they're there!


----------



## erneboy (Feb 8, 2007)

Fins in your box. Good point. Mostly they used to be made of a net type material to allow air flow but of course if they are solid then the air needs a way out.


----------



## raynipper (Aug 4, 2008)

I did find with my ride on mower that if the blades and therefore the skirt was set too low, it didn't allow enough airflow to 'blow' the grass up the shute into the hopper bag.
I would prefer to 'scalp' my lawn but have to put up with a No.2.

Ray.


----------



## raynipper (Aug 4, 2008)

New version of my Robomow.............................






Ray.


----------



## Penquin (Oct 15, 2007)

My advice based on cutting 1Ha frequently (4 times this year so far) with three different styles of mower is that dried grass underneath will alter the exit flow so it needs cleaning out and the cutting blades need cleaning and probably sharpening as all of those reduce the speed with which it is expelled BUT also if the grass is damp or even wet it will form clumps VERY quickly - it could well be a combination of all of those factors.

So, clean everything as well as possible, remove all dried on grass from the blades, the housing for the blades, the chute and any tubes. Then try it with the engine revs flat-out (most mowers stipulate that). If it is still clumping it is probably too long to cut at that position - take the grass off a bit at a time NOT all 5" at once - if it is that long, cut the top 1" off, let it dry then another 1 - 2" off and so on - more work but it will make a better job.

ONLY cut when the grass is dry - late afternoon rather than early morning and whatever you do the dandelions will be back within 36 hours - I can vouch for that......

Hope that helps, it is the same for ALL mowers, clean and sharp blades and a decent cutting speed are essential on dry grass or as dry as possible.

Dave


----------



## erneboy (Feb 8, 2007)

Now there's a thing I've never understood. I don't remember ever meeting an amateur who thought they could cut grass in the wet and I've certainly never met a professional who didn't just get on with it regardless of the weather.


----------



## Penquin (Oct 15, 2007)

Agree Alan, when you cut grass water comes out anyway (it's about 80% water) so the pulp will get wet unless it dries VERY quickly - cut surfaces dry quicker of course and finely cutting grass smashes it up so the water can evaporate rapidly IF the weather is reasonably dry.

BUT if it is wet, so the grass will not dry, it forms large wet lumps under the mower - where the blades smash it all together at speed..... if the surface is clean it falls off (Some lawn mower cutting decks are now teflon sprayed, but I have no clue how long that lasts once away from the dealer..... - conundrum; how do you *stick *NON-STICK Teflon to a surface.....? Answers on a postcard to the Patent Office a you will have made a fortune once the word spreads.)

So wet grass is not good news, for professionals they keep their machines fairly clean and sharp - so the effect on their job is less of a problem. They also often mulch rather than collect so they simply shred the grass as it cuts and leave it on the surface - no grass to take away.......

So that could well be at least part of your answer.... our John Deere X320 mulches it all, but f there is too much it remains on the surface for a while and often oly goes once another cut shreds it again.....

Grass by itself is NOT good for composting apparently as it forms a dense layer with insufficient air to allow breakdown - so mix it with shredded cardboard to aid rotting.....

There you are, gardening tips for your MoHo too..... Isn't MHF useful.....

I suspect the reason why amateurs won't cut wet grass may have other reasons as well.......

Surveying a freshly cut lawn in sunshine on a chair with a beer or wine in one hand is much nicer in sunshine than when raining.....

Dave


----------



## raynipper (Aug 4, 2008)

Dave, you are in the 'tropics' and the grass is hardly wet. But up here in Normandy everything is wet.
I can't mow before 14.00 any day.
If I use the ride on the shute clogs immediately and if I use the Robomow you can hear it labouring and battery life is halved.

Ray.


----------



## Penquin (Oct 15, 2007)

Ray,

Our "tropics" are obviously experiencing tropical monsoons as our lawn is currently flooded at the bottom - it has been raining virtually all day after a few days dry weather - the dandelions will be in fine form by tomorrow.....

Dave


----------



## erneboy (Feb 8, 2007)

My company cut a lot of grass, hundreds of hectares on a ten day cycle. As you say mostly we didn't collect it but in some areas collection was required which meant that we had large quantities of grass clippings to dispose of. Originally we brought it back to the yard and used a soil shredder to mix it (unrotted) and other composted organic material with clay soils. This gave us a ready supply of reasonably decent soil (capable of meeting the standard for top soil) for all kinds of jobs.

That became more complicated with the introduction of waste transfer regulations, because even though the clippings were not waste to us (they were part of a process to produce usable top soil) we couldn't get agreement that they could be classified as anything other than waste requiring disposal in a licenced, bunded tip. (Bunded to prevent any liquid escaping.) Then it became illegal to compost commercially (of course we weren't composting but that argument wasn't accepted) unless you had a licence for that. Getting a licence was an expensive business and would depend largely on the location and nature of your site. Given those difficulties we stopped cutting grass if collection was required.

Who'd have thought something as basic as cutting grass would become so difficult? I'm willing to bet that a little relaxation in the interpretation of the regulations would have solved the problem.

For instance golf courses can process their grass clippings. The differences between what they physically do and what we physically did are virtually nil. What matters is that in our case the clippings were classified as waste arising in the course of our work and that we had to transport them to our site meaning we needed a waste transfer licence. 

Of course typing this I see the way round it. Ten years too late. We could have paid the clients £1 a ton for the clippings as an essential ingredient in our top soil improving process. Hindsight eh?


----------



## raynipper (Aug 4, 2008)

FRIENDS, DOES THE FOLLOWING SOUNDS ABOUT RIGHT?????

Imagine the conversation The Creator might have had with St.
Francis on the subject of lawns:

GOD: Francis, you know all about gardens and nature. What in the world is going on down there? What happened to the dandelions, violets, thistle and stuff I started eons ago? I had a perfect,no-maintenance garden plan.
Those plants grow in any type of soil, withstand drought and multiply with abandon. The nectar from the long lasting blossoms attracts butterflies, honey bees and flocks of songbirds. I expected to see a vast garden of colors by now. But all I see are these green rectangles.

ST. FRANCIS: It's the tribes that settled there, Lord. The Suburbanites. They started calling your flowers "weeds" and went To great lengths to kill them and replace them with grass.

GOD: Grass? But it's so boring. It's not colorful. It doesn't attract butterflies, birds and bees, only grubs and sod worms. It's temperamental with temperatures. Do these Suburbanites really want all that grass growing there?

ST. FRANCIS: Apparently so, Lord. They go to great pains to grow It and keep it green. They begin each spring by fertilizing grass and poisoning any other plant that crops up in the lawn.

GOD: The spring rains and warm weather probably make grass grow
really fast. That must make the Suburbanites happy.

ST. FRANCIS: Apparently not, Lord. As soon as it grows a little,
they cut it -- sometimes twice a week.

GOD: They cut it? Do they then bale it like hay?

ST. FRANCIS: Not exactly, Lord. Most of them rake it up and put it
in bags.

GOD: They bag it? Why? Is it a cash crop? Do they sell it?

ST. FRANCIS: No Sir. Just the opposite. They pay to throw it away.

GOD: Now let me get this straight. They fertilize grass so it will
grow. And when it does grow, they cut it off and pay to throw it away?

ST. FRANCIS: Yes, Sir.

GOD: These Suburbanites must be relieved in the summer when we cut
back on the rain and turn up the heat. That surely slows the growth and saves them a lot of work.

ST. FRANCIS: You aren't going to believe this Lord. When the grass stops growing so fast, they drag out hoses and pay more money to water it so they can continue to mow it and pay to get rid of it.

GOD: What nonsense. At least they kept some of the trees. That was a sheer stroke of genius, if I do say so myself. The trees grow leaves in the spring to provide beauty and shade in the summer. In the autumn they fall to the ground and form a natural blanket to keep moisture in he soil and protect the trees and bushes. Plus, as they rot, the leaves form compost to enhance the soil. It's a natural circle of life.

ST. FRANCIS: You better sit down, Lord. The Suburbanites have drawn a new circle. As soon as the leaves fall, they rake them into great piles and pay to have them hauled away

GOD: No. What do they do to protect the shrub and tree roots in the
winter and to keep the soil moist and loose?

ST. FRANCIS: After throwing away the leaves, they go out and buy
something which they call mulch. They haul it home and spread it
around in place of the leaves.

GOD: And where do they get this mulch?

ST. FRANCIS: They cut down trees and grind them up to make the mulch.

GOD: Enough. I don't want to think about this anymore. St. Catherine, you're in charge of the arts. What movie have they scheduled for us tonight?"

ST. CATHERINE: "Dumb and Dumber", Lord. It's a really stupid movie about..

GOD: Never mind, I think I just heard the whole story from St.FRANCIS.


----------



## emmbeedee (Oct 31, 2008)

If you follow the (good) advice above to clean the underside be VERY careful to watch what is happening to the engine oil when you tip it over. A few years ago the neighbour over the road came & asked me to look at his mower which seemed to have seized. It would not pull over at all, just solid resistance when you tried. After removing the plug lead, I tried turning the blade underneath but no joy there either. I then took the plug out & it pulled over no problem, but a lot of oil flooded out of the plug hole. I told him he'd had a hydraulic lock but he didn't know what that was.
I asked him if he had turned the mower on its side to clean underneath. He denied it, but I'm sure that's what had happened, how else would oil get in there? To be fair to him, maybe one of his three sons had turned it over.
Anyway, I pulled it over a few times to blow all the oil out & after checking the oil level (still OK, must have been overfull) cleaned the plug & checked the spark, which was good. I then replaced the plug & pulled it over. It started straight away but poured smoke out, the carburettor must have been full of oil as well. I don't think the neighbour behind his house was best pleased though, all the smoke went through the fence into his place. After about five minutes running the smoke finally cleared & it ran fine & still does, now passed on to another neighbour. Before coming to me he thought it was scrap & was ready to take it to the tip. 
Another danger with tipping the mower over is the oil running out & not leaving enough in the sump for lubrication! I've replaced at least two engines in the past where the owners tipped them over & failed to check the oil level afterwards, so be warned. If you run the engine low on oil the next thing will be a loud bang, then you will find a hole in the side of the crankcase with a con-rod sticking out.:surprise:
If you tip it over on your lawn the spilt oil doesn't do your grass much good either.:frown2:


----------



## raynipper (Aug 4, 2008)

Hi emmbeedee.
Maybe you can answer this for me.?
I just bought a MTD Spider 91 SD ride on mower cheap. It needed a replacement starter which I have done. 
It now starts OK but the transmission is very jerky It's a 'Transmatic' 5 speed and will drive OK in reverse. But in forward drive it's like having hick-ups.
I can't see but would guess it's low on fluid. Do they use Dextron and how to top up please?

Ray.


----------



## Pudsey_Bear (Sep 25, 2008)

raynipper said:


> FRIENDS, DOES THE FOLLOWING SOUNDS ABOUT RIGHT?????
> 
> Imagine the conversation The Creator might have had with St.
> Francis on the subject of lawns:
> ...


I looked for this the other day to send to Liz as she had asked me to mow the lawn, but I did it last year:roll:


----------



## kabundi (Feb 14, 2011)

A couple of other thoughts

On many machines there are vents or other openings on top of the deck to allow air to be drawn in to below the deck to carry the grass into the box/bag. These vents can get blocked with dried grass over a period.

If you have a power washer then power wash all of the areas that grass passes over/through. If the collection is into a bag you should also power wash the bag to clean all the mesh, just don't put the nozzle too close to the mesh.

A sharp blade is also critical as the cuttings have to be clean cut and leave the blade with velocity. If the blade is not sharp then the grass is being chewed rather than cut.


----------



## emmbeedee (Oct 31, 2008)

raynipper said:


> Hi emmbeedee.
> Maybe you can answer this for me.?
> I just bought a MTD Spider 91 SD ride on mower cheap. It needed a replacement starter which I have done.
> It now starts OK but the transmission is very jerky It's a 'Transmatic' 5 speed and will drive OK in reverse. But in forward drive it's like having hick-ups.
> ...


Hi Ray, sorry I don't know that mower or the transmission. Assuming it's some type of automatic, it may be a clutch problem so I would recommend draining the transmission, removing the sump & cleaning or replacing the filter, if there is one. Then fill up with new fluid, of course. I fixed a couple of Chrysler transmissions in the States by doing just that, but difficult to say without more knowledge of the unit. Otherwise, could it be a chipped gear tooth?
I did briefly own a lawnmower repair shop, but that was 35 years ago so my knowledge is somewhat out of date.:laugh: 15 years before that I was running a shop making 1,000 or so of these type of engines every week & although the basics of the engines haven't changed too much some of the ancillaries certainly have.
Sorry I can't be of more help in this instance, have you tried Mr. Google? Also, Kev from Leeds seems to be expert at finding YouTube videos of all sorts of problems, maybe some help available there?


----------



## raynipper (Aug 4, 2008)

Thanks emmbeedee.
After seeing a Youtube video here about rebuilding the transaxle I think it might be loose belts......






Thanks Ray.


----------



## Pudsey_Bear (Sep 25, 2008)

Have you noticed american mechanics have a fascination for adjustable spanners in most videos, I was always taught that they were called adjustable because you could bugger up different sized bolts and nuts.


----------

