Lawn-Boy M Series Brought Back to Life

[EricF 589]

This is my M-series Lawn-Boy mower that I've had since it was new, around 1994? or so -- it's been a while and I forget little details. Enough to know I bought it brand-new; it's the second-generation version of the M-series where they re-worked the final drive at the rear wheels slightly. It was my only mower at the time on a small city lot in Indianapolis, and it replaced a cranky F-series Lawn-Boy that came with the house I inherited. The "F" was one of the odd green-and-yellow(!) ones which ran well enough, but tended to balk and need service at the worst possible times. The "M" series was like nothing anyone had seen before, back in the 90s. Magnesium deck. Oil injection, like on a snowmobile or good dirt bike. Magnetic safety switch to detect that a bagger or chute was attached, not a contact to rust or get dirty. Piston ported engine instead of the old reed valve design. Mine came with the blade clutch, so you could step away from the machine while it idled, unlike the then-new (and annoying) "zone start" safety system where you have to hold the bail on the handle or the engine shuts down. It also meant you could stop the blade any time to travel through areas without kicking up dust. The only thing it didn't come with was an electric starter, something I'm happy to do without the complication of even to this day. A Lawn-Boy two-stroke engine should start on the first or second pull -- third one if it's sat a while -- and "pull" is kind of a stretch of the word; "spin" is more like it -- they're ridiculously light and easy to start.

 

This one was my only mower through two houses in Indianapolis as I started a family, then it came out to New Hampshire with us and worked two more yards until it started having problems starting. My brother-in-law brought over an old Snapper Hi-Vac that had been in my wife's family since the 80s, and then left it behind. The old Snapper then became the alternate while I tinkered with the Lawn-Boy. I got the Snapper tuned up (and my wife's family thought it was mostly dead...) and so I had two interesting mowers to work with. (I love the simple miniature snowthrower disc drive on the Snapper Hi-Vacs!) We moved again, this time to a property large enough to need a lawn tractor. The Lawn-Boy got a bit of a rest now that it only had to work as a trimmer, but it began having difficulty starting again. So it got put aside and the old Snapper got a carb rebuild, new belts, and got put back to work. That's how it's been for the past number of years, especially since the trimming at that house's yard, the next one, and the one we're in now have had so much sand and rough ground that I really didn't want to beat the Lawn-Boy up on them. Two things came together this year -- with a bit of work, the lawn is coming in nicely so I'm not mowing over so much sand. And the old Snapper is getting genuinely balky -- pretty sure the 35-or-so-year-old Briggs engine is losing compression, one of the front axle mounts is worn severely oval, the belts are worn out again, and the idler pulley on the miniature disc drive is in need of a new bearing. So it was time to dig into the faithful Lawn-Boy and see what was going on.

 

Like so many times with the simple Lawn-Boy 2-strokes, it turned out to be a simple problem. Pinched wires! A pair of wires that run to the ignition module provide continuity against the safety shutoff and low-oil cutout function. They'd gotten pinched in two places when the engine shroud was re-assembled at some point when it was serviced. All it took was splicing in a short run of wire and she started right up! 

 

Now, the wires are wrapped securely with 3M electrical tape like a stiff car wiring harness instead of the thin PVC sleeve that came from the factory, and carefully tucked up in the engine shroud away from where they were pinched before. The starter rope was getting frayed, so I put a new one on. Greased the zerks for the power drive and put some Sea Foam in the fuel. Now it just has to stop raining so I can go out and mow!

 

Here she is -- well worn but ready to mow for probably another 20 years or more!

 

Yes, she's missing the green plastic trim on the muffler housing. It was held on by tabs on the back and the pair of screws you can see on the front, which didn't really go through the plastic trim -- just a couple of loops molded onto the bottom of the trim. Naturally, those loops give up after a while. I think the trim piece might have gotten lost or misplaced in a move at some point. If it surfaces, I'll try to figure out a way to put it back on.

 

Here she is from behind. In need of some paint on the access panel that covers the Tuff-Torq drive unit, but everything is working just fine. The mulch plug is installed right now. There's a slightly odd discharge chute that throws to the left, and a rear-mount bag, too. You can see the "windows" that reveal the fuel and oil tank levels that were kind of innovative at the time.

 

One downside to the M-series is that it's not easy to get to all the fasteners to loosen the fuel and oil tanks and the engine shroud. If you have big hands, it's miserable. I'm not that bad off, but it's tricky and darn uncomfortable.

 

 

It's not camera distortion -- the handle, it's adjustment knobs, and the drive and blade bails really are that beefy. Channel aluminum bars, and big castings. It looks like what happens when engineers get a hold of a lawn mower design. I've always liked the typical Lawn-Boy heavy vinyl debris flap. It's still flexible after all these years, and it won't bounce and flip up like stiff plastic or metal ones.

 

Here's a shot -- top-quality lawn care equipment, old-school 1990s-style!

 

 

Next time I'm in in the big-box store and the guy in the lawn and garden department asks if I need something, I think I'll show him this picture and say, "Nope, I think I'm all set, thank you!"

 

Historically, Toro kept the M-series deck and drive system in their own-brand commercial line after buying Lawn-Boy, although environmental regulations killed off the 2-cycle engine. Their high-end commercial trimming mowers use a 2nd-generation version of the deck, cast in aluminum instead of magnesium. Some of the sharp angles have been rounded off a bit, and the front edge looks like it has a thickened lower edge. Steel reinforcements in the height-adjuster notches. And the crazy-over-built handle is replaced by a more conventional steel tube stock one. But deep down, a bit of this beast still lives on. (And meanwhile, this one's companion, the Snapper Hi-Vac, is still in production too!)

[T-Mo-(Moderator) 4,505]

I'm a big fan of the Lawn Boy mowers.  Love them and I had a few of them.  They're light weight and with the two stroke engines, mowing on a hill side isn't a concern.  I wish I had another one as I sold the ones I did have.

[EricF 589]

I have a soft spot for old 2-stroke lawn-boys, although it's a little bit of a love-hate relationship going on. When they're running right, they're a pleasure to run. When they're off, they're annoying as heck because you just know they can behave better. I've always suspected Lawn-Boy had good and bad years. It's the only way to explain why some would be trouble-free, and other identical models from other years tended to be failure-prone; that seemed to be the theme in the 80's at least, when I used them the most. The F-series one that the "M" replaced went through two worm gears for the capstan drive, despite regular lubrication and service. Others like it I've known never gave any trouble. The green-and-yellow "F" also had a carb issue, then it lost the ignition module before it finallly got traded off for the "M". The shop I was taking it to probably could have gotten it straightened out once and for all, but the "M" was just too tempting. Originally, that house's lawn was mowed with a 19" "bricktop" Lawn-Boy from the 60s. That one ran like a top and was so light it was like nothing at all to push. Unfortunately, when the relative who owned the house passed, an acquaintance of the family absconded with it... Otherwise I'd have kept that one forever. On the other hand, when my future wife-to-be got a house and needed a lawn mower, I picked up another used "F" series mower from the repair shop that was just like my old one (only all-green like a Lawn-Boy ought to be) -- and it never gave a lick of trouble. When she moved in with me, we gave that one to a neighbor when their hardware-store special gave up the ghost.

 

I mowed lawns with various Lawn-Boys... some were smokers, some weren't. The capstan drive worked well, but often needed to be snugged up with the big clamp on the actuator rod beside the handle. Pushing them uphill on rougher ground could be a chore, not because of the weight, but because the handles had a lot of up-and-down play in them which was fine on flat ground, but flopped around a lot when you pushed uphill -- for hills, the power-drive option was the only way to go. I ran one that had the electric starter -- nifty, when it worked. But that particular engine never liked to start until 4 or five spins, so it tended to run the battery down. Easier and faster to spin it with the pull-rope. The side-bagger tended to fill up fast and clogged easily if the grass was moist. Using them with the side discharge was easier, but they still could get a lot of nasty buildup under the deck. The stagger-wheel design didn't have a lot of suction or debris-clearing airflow compared to things like Toro's decks, or high-vacuum designs from Snapper and John Deere. Better blades helped, but they were never really designed for that kind of performance. That's where the "M" design really caught my eye -- A bulletproof 2-cycle engine with a high-vacuum deck and modern mulch/bag system. The four-square wheels wouldn't tend to wander like a stagger-wheel deck, especially when bagging. Even the "M"s were known for troubles with the power drive in the earlier versions. The later ones like mine had the bugs worked out. Lawn-Boys always seemed to be quirky beasts, but unstoppable if they were sorted out by a good mechanic. If you ran one that was in good condition, you'd be hooked for life on 'em!

[wh500special 2,188]

This is my first mowing season since about 2000 without a lawnboy in my garage.  I've had several and loved every one of them.   One I bought new in 2001 and it was the last to go.  In all those years they required such little maintenance and started right up each time.  

 

Great, lightweight, and powerful mowers.   I was really just ready for something new, but I justified getting rid of them because one of them needed a $30 coil.    In 17 years, that was the only failure I had.   Outstanding reliability. 

 

Thanks for the info on the m-series.  I had no idea they had automatic oiling.  

 

It's too bad that old-school two strokes are so dirty...what a practical and power dense little package they are. 

 

Nice story.  

 

Steve

[EricF 589]

The "consumer" M-series had the oil injection. You'll sometimes find a "commercial" M-series and it will have the same engine but no oil injection. They use a larger fuel tank and pre-mixed gas/oil like a normal Lawn-Boy.

[WHX?? 48,833]

In the late 60's  when I was a kid the neighbors had a green lawn boy but it was a model that had the starter cord that you pulled straight up. It always started with just a couple of those "spins" and we used to go get it and off we went  to knock on doors and offer cut neighborhood lawns for 50 cents.  We spent it as fast as we could make it on penny candy & matchbox cars! It smoked like the devil but I'm sure we were overmixing the oil/gas as we had no clue back then.  One day we had to make some quick cash for a new soda that just came out and had no oil so I "borrowed" some of dads 30 weight and away we went. Never hurted the mower abit.

[EricF 589]

You know, one thing I miss on the "M" is the old straight-up pull start.

 

Since mine is the blade-brake clutch model, the top-mounted pull start is pointed more or less to the front left wheel... but the step ridges on the deck are at the traditional 9:00 position on the left side. Which works pretty well if you're a lefty, but if you're right-handed, you wind up pulling the rope off-center and upward instead of out at about a 45-degeree angle. So it tends to wear out the starter rope. I just replaced mine, in fact. On zone-start models, it's a non-issue; the rope pulls nice and straight out toward to the back because the pull-start cover is just rotated around to the different position. Just one of those things that kind of got lost along the way when the industry went to the zone-start system where you pull-start from behind the handle.

[wh500special 2,188]

You mentioned the tracking issues with the staggered wheel arrangement...

 

I just remembered that an uncle - who always had a pair of lawnboys and a Wheel Horse in his garage - had a LB that had a spring loaded wheel on that far right corner by the discharge chute.  Although I'm sure the one he had wasn't rare, I'd never seen another that had that feature.  I'll bet it was to keep it from wandering.

 

One of my neighbors made a comment after my first mowing with my new mower this spring that he noticed I had something new because of the sound.  My new mower is a 4-stroke and is more "conventional" sounding I guess.  I miss the 2-stroke buzz.

 

Ole Evinrude would be proud.

 

Steve

[EricF 589]

23 hours ago, wh500special said:

I just remembered that an uncle - who always had a pair of lawnboys and a Wheel Horse in his garage - had a LB that had a spring loaded wheel on that far right corner by the discharge chute.  Although I'm sure the one he had wasn't rare, I'd never seen another that had that feature.  I'll bet it was to keep it from wandering.

I've never seen that, either. Was it a spring on the axle or wheel mount to keep the wheel pointed against the direction it tended to pull when the bag was full? Could have been a clever bit of DIY engineering.

 

23 hours ago, wh500special said:

One of my neighbors made a comment after my first mowing with my new mower this spring that he noticed I had something new because of the sound.  My new mower is a 4-stroke and is more "conventional" sounding I guess.  I miss the 2-stroke buzz.

I spotted one of the neighbors making a few extra trips with lawn cleanup to go where he could see what I was mowing with the other day when I had the "M" out for trimming... I think the 2-stroke sound caught his attention!

 

Of course, the 520H always seems to attract his attention, too.

[wh500special 2,188]

520's sound great, no doubt about it!

 

I don't remember well enough to know how it was executed.  it certainly wasn't my uncle's fabrication since he wasn't the least bit of a tinkerer.  I want to say the whole height adjust quadrant was on a pivot with a spring holding it in place but it's been too many years. 

 

My uncle is the type that takes fanatical care of his belongings and he only bought the best of everything.  I haven't been to his house in years, but I should make an effort to ask if he still has the LB's...he probably does.

 

Steve

[Fordiesel69 263]

I never understood why they let the exhaust out the bottom.  It made for one stinky lawn mowing job which you would need to detox for a week!  I owned one that required a 16:1 mix.  You could not use it without a portable respirator system.  We settled on 20:1 instead but even then it was bad.  I will agree though nothing sounds nicer!!!!  They also mowed significantly nicer than other mowers of their era.  

[ebinmaine 67,653]

On 8/5/2017 at 7:59 PM, EricF said:

Next time I'm in in the big-box store and the guy in the lawn and garden department asks if I need something, I think I'll show him this picture and say, "Nope, I think I'm all set, thank you!"

'Round here there's an old saying - "use what you have".

My honey and I try as much as possible to do so. 

I love the fact that so many of us will fix and repair a decades old machine for ... decades more, before buying a new poopie pile disposable.

[EricF 589]

Yeah, I have an aversion to spending money on anything that won't last. Better to repair what you have -- and buy what can be repaired rather than thrown out. Funny story -- a month or so ago, the doorbell rang. It was somebody selling Kirby vacuum cleaners door-to-door. Sorry, can't help you, I told them -- we already have one. I don't think they were expecting that answer -- Kind of hard to sell when the prospective customer already owns one.  The thing is about 25 years old and going strong. Bought it used, too; it gets checked out by the local Kirby service guy every few years. Much like a Wheel Horse, it's a machine that the parts largely interchange on across decades of production, so keeping an old one running is easy and inexpensive. My wife has asthma, so we keep the house scrupulously clean. The old machine, with the modern HEPA-grade bags I can get for it, still gets more crud and pet hair out of rugs than the new "high efficiency" and "allergy care" vacuums. Come to think of it, it's probably time to get out the metal polish and shine it up again -- can't do that with the modern plastic throwaways!

 

Update... A couple of weeks ago I went to mow. Got the Lawn-Boy out to do the trimming. No start. Checked the plug, found no spark when cranking. After running down the tests in the shop manual to check all the safety cut-outs, it came down to a bad ignition module. All of them seem to be Chinese imports now, even the slightly different-looking ones that have been the usual substitution from a German supplier. Searching for the appropriate part turned them up on Amazon, of all places, along with a new spark plug. Easy enough part to swap, but it's a pain to remove the engine shroud because you also have to loosen the muffler shroud and lift the gas/oil tank assembly. Lots of screws in hard-to-reach places. Well now it's back together and running like a champ again, just in time to chew up all the leaves that have come down plus the grass that grew up during the warm weather and rains of late. Nothing beats a 2-cycle engine for torque under heavy load -- It plowed through all the leaves and grass with the mulch plug in place, no problem at all. It's a perfect companion to the 520H for getting work done in a hurry.

[Terry M-(Moderator) 2,175]

Refurbished my Lawn Boy last summer.   Bought it new about 18years ago and it was only last year that it had issues with it running. it started to run poorly and  only at half choke.    Not liking anything else available on the market, I tore it down to see if I could find a problem.   Seems the lower crank seal on the engine was tore-up.   So I decide to replace both seals, some gaskets , Brand new carburetor , fuel line , primer bulb and line , New drive belt, four brand new O.E.M. wheels and some other odds and ends .   Now it runs like New and I'm hoping I can get another 15 to 20 years out of it.    Thinking too of finding a second used one and refurbishing it  .    Love those Lawn Boys!!

 

[Wiserazor 2]

On 8/5/2017 at 7:59 PM, EricF said:

This is my M-series Lawn-Boy mower that I've had since it was new, around 1994? or so -- it's been a while and I forget little details. Enough to know I bought it brand-new; it's the second-generation version of the M-series where they re-worked the final drive at the rear wheels slightly. It was my only mower at the time on a small city lot in Indianapolis, and it replaced a cranky F-series Lawn-Boy that came with the house I inherited. The "F" was one of the odd green-and-yellow(!) ones which ran well enough, but tended to balk and need service at the worst possible times. The "M" series was like nothing anyone had seen before, back in the 90s. Magnesium deck. Oil injection, like on a snowmobile or good dirt bike. Magnetic safety switch to detect that a bagger or chute was attached, not a contact to rust or get dirty. Piston ported engine instead of the old reed valve design. Mine came with the blade clutch, so you could step away from the machine while it idled, unlike the then-new (and annoying) "zone start" safety system where you have to hold the bail on the handle or the engine shuts down. It also meant you could stop the blade any time to travel through areas without kicking up dust. The only thing it didn't come with was an electric starter, something I'm happy to do without the complication of even to this day. A Lawn-Boy two-stroke engine should start on the first or second pull -- third one if it's sat a while -- and "pull" is kind of a stretch of the word; "spin" is more like it -- they're ridiculously light and easy to start.

 

This one was my only mower through two houses in Indianapolis as I started a family, then it came out to New Hampshire with us and worked two more yards until it started having problems starting. My brother-in-law brought over an old Snapper Hi-Vac that had been in my wife's family since the 80s, and then left it behind. The old Snapper then became the alternate while I tinkered with the Lawn-Boy. I got the Snapper tuned up (and my wife's family thought it was mostly dead...) and so I had two interesting mowers to work with. (I love the simple miniature snowthrower disc drive on the Snapper Hi-Vacs!) We moved again, this time to a property large enough to need a lawn tractor. The Lawn-Boy got a bit of a rest now that it only had to work as a trimmer, but it began having difficulty starting again. So it got put aside and the old Snapper got a carb rebuild, new belts, and got put back to work. That's how it's been for the past number of years, especially since the trimming at that house's yard, the next one, and the one we're in now have had so much sand and rough ground that I really didn't want to beat the Lawn-Boy up on them. Two things came together this year -- with a bit of work, the lawn is coming in nicely so I'm not mowing over so much sand. And the old Snapper is getting genuinely balky -- pretty sure the 35-or-so-year-old Briggs engine is losing compression, one of the front axle mounts is worn severely oval, the belts are worn out again, and the idler pulley on the miniature disc drive is in need of a new bearing. So it was time to dig into the faithful Lawn-Boy and see what was going on.

 

Like so many times with the simple Lawn-Boy 2-strokes, it turned out to be a simple problem. Pinched wires! A pair of wires that run to the ignition module provide continuity against the safety shutoff and low-oil cutout function. They'd gotten pinched in two places when the engine shroud was re-assembled at some point when it was serviced. All it took was splicing in a short run of wire and she started right up! 

 

Now, the wires are wrapped securely with 3M electrical tape like a stiff car wiring harness instead of the thin PVC sleeve that came from the factory, and carefully tucked up in the engine shroud away from where they were pinched before. The starter rope was getting frayed, so I put a new one on. Greased the zerks for the power drive and put some Sea Foam in the fuel. Now it just has to stop raining so I can go out and mow!

 

Here she is -- well worn but ready to mow for probably another 20 years or more!

 

Yes, she's missing the green plastic trim on the muffler housing. It was held on by tabs on the back and the pair of screws you can see on the front, which didn't really go through the plastic trim -- just a couple of loops molded onto the bottom of the trim. Naturally, those loops give up after a while. I think the trim piece might have gotten lost or misplaced in a move at some point. If it surfaces, I'll try to figure out a way to put it back on.

 

Here she is from behind. In need of some paint on the access panel that covers the Tuff-Torq drive unit, but everything is working just fine. The mulch plug is installed right now. There's a slightly odd discharge chute that throws to the left, and a rear-mount bag, too. You can see the "windows" that reveal the fuel and oil tank levels that were kind of innovative at the time.

 

One downside to the M-series is that it's not easy to get to all the fasteners to loosen the fuel and oil tanks and the engine shroud. If you have big hands, it's miserable. I'm not that bad off, but it's tricky and darn uncomfortable.

 

 

It's not camera distortion -- the handle, it's adjustment knobs, and the drive and blade bails really are that beefy. Channel aluminum bars, and big castings. It looks like what happens when engineers get a hold of a lawn mower design. I've always liked the typical Lawn-Boy heavy vinyl debris flap. It's still flexible after all these years, and it won't bounce and flip up like stiff plastic or metal ones.

 

Here's a shot -- top-quality lawn care equipment, old-school 1990s-style!

 

 

Next time I'm in in the big-box store and the guy in the lawn and garden department asks if I need something, I think I'll show him this picture and say, "Nope, I think I'm all set, thank you!"

 

Historically, Toro kept the M-series deck and drive system in their own-brand commercial line after buying Lawn-Boy, although environmental regulations killed off the 2-cycle engine. Their high-end commercial trimming mowers use a 2nd-generation version of the deck, cast in aluminum instead of magnesium. Some of the sharp angles have been rounded off a bit, and the front edge looks like it has a thickened lower edge. Steel reinforcements in the height-adjuster notches. And the crazy-over-built handle is replaced by a more conventional steel tube stock one. But deep down, a bit of this beast still lives on. (And meanwhile, this one's companion, the Snapper Hi-Vac, is still in production too!)

Hello  from a Newbie  I just had the same mower dropped-off Has No Spark it also has No Mulching Plug or Bag. I am assuming it must have one or the other for it to spark (just like some of the newer Lawnboys by Toro)  Is this correct if so I guess I will have to disable the safety feature for Testing ???

[EricF 589]

Is yours a blade brake model (Starter rope pulled while standing to side of mower, like in my pictures) or a flywheel brake model (Starter rope pulled from behind mower)? Only a blade brake type can be safely tested without a chute/bag or mulch plug in place

 

I won't advocate bypassing the chute interlock, especially on a non-blade brake model. The discharge opening is straight out the back of the mower -- if the blade is turning, it WILL send anything it can pick up out and UPWARD toward you, bystanders, or anything behind the mower. You need to get a hold of a proper much plug, chute, or bag first. It's not safe to begin testing until that's in place!

 

There are several safety switches on the M series -- some are simple contact switches, others are magnetic. Magnetic switches are used where purely mechanical ones are more likely to fail -- the magnet is used to close or open the switch depending on its function. That makes checking the interlocks a little different from working with normal mechanical-only switches.

 

These are the typical switches; not all are present on all models:

• Throttle Switch (All models) - Closed when the throttle is pulled all the way back to the shut-off position, open at all other positions
• Low Oil Shutoff (Oil injection models only -- has separate oil tank) - Closed when float is down at low oil level position, open when float is above. Overrides all other switches to protect the engine.
• Flywheel (engine) Brake Switch (All models without Blade Brake Clutch; blade always runs with engine) - Open when bail is pulled back, closed when bail is released
• Blade Brake Clutch Switch (Blade Brake models only; engine remains running but blade stops when bail is released) - Closed when bail is pulled back, Open when bail is released.
• Chute Interlock (All models) - Closed when chute, bag, or mulch plug is not present, open when chute, bag, or mulch plug is present. Use only non-magnetic screws if the magnet has to be replaced, or the switch will not operate

The Flywheel Brake and Blade Brake Clutch switches are interconnected with the Chute Interlock. The interlock works differently depending on which brake system is installed:

• A mower equipped with the Flywheel Brake can't start or run unless the Chute interlock detects a chute, bag, or mulch plug in place. (Chute Interlock always overrides)
• A mower equipped with the Blade Brake Clutch can start with no chute, bag, or mulch plug in place, but the engine will stop if the bail is pulled back unless the chute, bag, or mulch plug is in place. (Chute Interlock inactive until bail is pulled back)

The Chute Interlock is fail-safe. It is closed to ground the ignition out unless it's opened by having a chute, bag, or mulch plug in place

Only a Blade Brake Clutch mower can start with no discharge device attached. The engine will stop if the bail is pulled back because that engages the blade and brings the Blade Brake Clutch switch into the circuit.

A Flywheel Brake mower can't start at all unless a discharge device is installed, because the Flywheel Brake Switch is always in the circuit.

 

The Low Oil Shutoff is always active. If the float has failed (sinks to the bottom even if the tank is full) or the switch is bad, it will never start.

 

The Throttle Switch can fail either on or off. If the throttle cable is out of adjustment, it may not pull the switch closed and the only way to shut the engine off is to reach down and push the throttle linkage all the way back so that it contacts the switch and closes it.

 

Proceed with ignition diagnostics only if you have a Blade Brake model. If yours has the rear-mounted pull rope, it's a Flywheel Brake type and you must have an attachment in place to open the interlock switch. Attempting to bypass it its very unsafe. You'll need a chute/bagger or mulch plug before you can do anything else.

[Wiserazor 2]

On 5/31/2021 at 9:16 PM, EricF said:

Is yours a blade brake model (Starter rope pulled while standing to side of mower, like in my pictures) or a flywheel brake model (Starter rope pulled from behind mower)? Only a blade brake type can be safely tested without a chute/bag or mulch plug in place

 

I won't advocate bypassing the chute interlock, especially on a non-blade brake model. The discharge opening is straight out the back of the mower -- if the blade is turning, it WILL send anything it can pick up out and UPWARD toward you, bystanders, or anything behind the mower. You need to get a hold of a proper much plug, chute, or bag first. It's not safe to begin testing until that's in place!

 

There are several safety switches on the M series -- some are simple contact switches, others are magnetic. Magnetic switches are used where purely mechanical ones are more likely to fail -- the magnet is used to close or open the switch depending on its function. That makes checking the interlocks a little different from working with normal mechanical-only switches.

 

These are the typical switches; not all are present on all models:

• Throttle Switch (All models) - Closed when the throttle is pulled all the way back to the shut-off position, open at all other positions
• Low Oil Shutoff (Oil injection models only -- has separate oil tank) - Closed when float is down at low oil level position, open when float is above. Overrides all other switches to protect the engine.
• Flywheel (engine) Brake Switch (All models without Blade Brake Clutch; blade always runs with engine) - Open when bail is pulled back, closed when bail is released
• Blade Brake Clutch Switch (Blade Brake models only; engine remains running but blade stops when bail is released) - Closed when bail is pulled back, Open when bail is released.
• Chute Interlock (All models) - Closed when chute, bag, or mulch plug is not present, open when chute, bag, or mulch plug is present. Use only non-magnetic screws if the magnet has to be replaced, or the switch will not operate

The Flywheel Brake and Blade Brake Clutch switches are interconnected with the Chute Interlock. The interlock works differently depending on which brake system is installed:

• A mower equipped with the Flywheel Brake can't start or run unless the Chute interlock detects a chute, bag, or mulch plug in place. (Chute Interlock always overrides)
• A mower equipped with the Blade Brake Clutch can start with no chute, bag, or mulch plug in place, but the engine will stop if the bail is pulled back unless the chute, bag, or mulch plug is in place. (Chute Interlock inactive until bail is pulled back)

The Chute Interlock is fail-safe. It is closed to ground the ignition out unless it's opened by having a chute, bag, or mulch plug in place

Only a Blade Brake Clutch mower can start with no discharge device attached. The engine will stop if the bail is pulled back because that engages the blade and brings the Blade Brake Clutch switch into the circuit.

A Flywheel Brake mower can't start at all unless a discharge device is installed, because the Flywheel Brake Switch is always in the circuit.

 

The Low Oil Shutoff is always active. If the float has failed (sinks to the bottom even if the tank is full) or the switch is bad, it will never start.

 

The Throttle Switch can fail either on or off. If the throttle cable is out of adjustment, it may not pull the switch closed and the only way to shut the engine off is to reach down and push the throttle linkage all the way back so that it contacts the switch and closes it.

 

Proceed with ignition diagnostics only if you have a Blade Brake model. If yours has the rear-mounted pull rope, it's a Flywheel Brake type and you must have an attachment in place to open the interlock switch. Attempting to bypass it its very unsafe. You'll need a chute/bagger or mulch plug before you can do anything else.

Thank-you for all the info got all figured-out, The engine and all the mechanics work perfect. The big challenge is the gas tank is cracked the oil tank still good. has anyone that you may know has a work-around on modifying the tank area with a replacement while keeping the stock look. Here is a picture.

 

Edited June 2, 2021 by Wiserazor

[EricF 589]

The oil tank and gas tank are molded together and assembled as a single piece, so if the crack is causing an active leak, you'll have to find a replacement for the whole thing.

 

FYI working around the tank to get it loose or removed is very fiddly with the way it's attached... And you have to at least get it free and moved back to pull the engine shroud for any reason -- like replacing the ignition module. A small 1/4" socket set and extensions is useful.

 

I know over the years, blade brake systems have sometimes gotten a bad rap, but the Lawn-Boy one in mine has been bulletproof and something I've always loved. Just like the PTO-driven mower on a tractor, you can stop the blade any time you want and just run the mower in power drive to go place to place for trimming. (3rd gear on these is pretty much just for zipping around between working spots; it's usually too fast to get a good cut. Again, a lot like a tractor -- a fast "transport" gear and lower "working" gears.)

 

If you need the service manual, I believe Toro has it available online -- that's how I got mine a few years back. Good to have, and de-mystifies everything really well.

[Wiserazor 2]

3 hours ago, EricF said:

The oil tank and gas tank are molded together and assembled as a single piece, so if the crack is causing an active leak, you'll have to find a replacement for the whole thing.

 

FYI working around the tank to get it loose or removed is very fiddly with the way it's attached... And you have to at least get it free and moved back to pull the engine shroud for any reason -- like replacing the ignition module. A small 1/4" socket set and extensions is useful.

 

I know over the years, blade brake systems have sometimes gotten a bad rap, but the Lawn-Boy one in mine has been bulletproof and something I've always loved. Just like the PTO-driven mower on a tractor, you can stop the blade any time you want and just run the mower in power drive to go place to place for trimming. (3rd gear on these is pretty much just for zipping around between working spots; it's usually too fast to get a good cut. Again, a lot like a tractor -- a fast "transport" gear and lower "working" gears.)

 

If you need the service manual, I believe Toro has it available online -- that's how I got mine a few years back. Good to have, and de-mystifies everything really well.

 

3 hours ago, EricF said:

The oil tank and gas tank are molded together and assembled as a single piece, so if the crack is causing an active leak, you'll have to find a replacement for the whole thing.

 

FYI working around the tank to get it loose or removed is very fiddly with the way it's attached... And you have to at least get it free and moved back to pull the engine shroud for any reason -- like replacing the ignition module. A small 1/4" socket set and extensions is useful.

 

I know over the years, blade brake systems have sometimes gotten a bad rap, but the Lawn-Boy one in mine has been bulletproof and something I've always loved. Just like the PTO-driven mower on a tractor, you can stop the blade any time you want and just run the mower in power drive to go place to place for trimming. (3rd gear on these is pretty much just for zipping around between working spots; it's usually too fast to get a good cut. Again, a lot like a tractor -- a fast "transport" gear and lower "working" gears.)

 

If you need the service manual, I believe Toro has it available online -- that's how I got mine a few years back. Good to have, and de-mystifies everything really well.

I did remove the tank and tried to fix the crack That worked for a few minutes, I would like to keep it as original as possible. I just may do a redneck fix by clipping a gas tank on the handle and leave the oem tank on. I would never spend $$$ on any  new Old New Stock, Plastic is plastic age just kills plastic. Enjoy your summer you have been very helpful.

[seuadr 488]

every time i see this thread my brain says "lowboy" and i go oh! hey! and click on it expecting to see a cub cadet and then am confused for several seconds

 

[Wiserazor 2]

1 hour ago, seuadr said:

every time i see this thread my brain says "lowboy" and i go oh! hey! and click on it expecting to see a cub cadet and then am confused for several seconds

 

Sorry for the confusion  I was desperately seeking info on the M-Series Ericf was a great guy and provide me with some good info

[seuadr 488]

4 hours ago, Wiserazor said:

Sorry for the confusion  I was desperately seeking info on the M-Series Ericf was a great guy and provide me with some good info

no worries, it is my fault, i forgetting and clicking on it!