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Restoring an old 1994 Lawn-Boy Gold-Series Model: 10520 Serial: 4901575 with a 4.5HP motor. Self-propelled model.
I know there are several threads and videos about how to remove a stuck blade nut by using impact wrench, heat, leverage bars, etc.... That isn't my problem. I did use a leverage bar, but what happened is I thought I broke the nut loose, but it appears the blade has broken loose. With the blade blocked with a piece of wood and clamp, I can use my socket wrench to spin the nut, shaft, and flywheel as one. How can I break the nut loose now? I thought about taking the gas tank and pull starter off and blocking the flywheel but am worried about breaking the fins on the flywheel. Wanted to check here first. Also thought about using a chisel to break the nut off and replace it (which I probably will do anyway). I suspect the muffler cover and/or plate-collar assembly will need replacing and are why the blade has loosened/broken from the shaft.

For those interested in the restore process: (this thing was left outside for 2 years in the upper midwest. Rusted up bad).
I've used a compression gauge with a schrader valve to test the compression to 103.
I've pulled, tested, and cleaned the spark plug. It appeared in good shape. Not too much carbon build-up.
I've pulled and cleaned the carb thoroughly. If it runs rough I may go ahead and buy a rebuild kit for it, but it passes the eye inspection.
I've pulled, cleaned, and flushed the gas tank and let it dry thoroughly. Pulled the shut-off valve and cleaned it also.
Old ignition coil (683080) was bad. No spark. Bought a cheap replacement which tested to provide spark. Will buy a more quality one in the future if I can get this bad boy running.
Cables were all seized up. Used Kreen Oil and WD40 to loosen them up. All seem operation now, but are rusty. Will replace in future as needed.
Deck needs repainting badly. Old paint is peeling off. Will get to that later.
Underside rusted up badly. Need to replace blades and clean the exhaust ports which is where I am and having the blade nut issue.

Help is appreciated.

p.s. I wasn't aware the model 10520 came with a 4.5hp. I thought it only came with a 5hp.

Been on the Internet all day trying to find out what I can. I found this from another forum posted back in 2012: "Try taking the spark plug out and stuff a length of rope into the cylinder. As you turn the nut, the rope will compress in the cylinder against the top of the piston acting as a stop, and keeps the pto shaft from turning." May give that a try tomorrow, but the idea of sticking something in the spark plug hole doesn't sit well with me.

Nessuno said:

Been on the Internet all day trying to find out what I can. I found this from another forum posted back in 2012: "Try taking the spark plug out and stuff a length of rope into the cylinder. As you turn the nut, the rope will compress in the cylinder against the top of the piston acting as a stop, and keeps the pto shaft from turning." May give that a try tomorrow, but the idea of sticking something in the spark plug hole doesn't sit well with me.

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Nessuno said:

Been on the Internet all day trying to find out what I can. I found this from another forum posted back in 2012: "Try taking the spark plug out and stuff a length of rope into the cylinder. As you turn the nut, the rope will compress in the cylinder against the top of the piston acting as a stop, and keeps the pto shaft from turning." May give that a try tomorrow, but the idea of sticking something in the spark plug hole doesn't sit well with me.

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The only thing you need to careful with is to make sure the con rod is at TDC.
If it is at an angle then when you apply a lot of force to the nut you can bend the con rod
Personally I would just cut it off.
If it is badly rusted then it should not be used for safety reasons so why risk the con rod.
The rope down the plug hole trick is generally used with an impact rather than a 12' long breaker bar with 10' of pipe on the end.

Sounds badly galled.

I don't think there's any way I'd stuff something into the spark plug hole. I'd go after that nut a lot more. Liquid Wrench (lots of applications over several hours), propane torch, nut cracker, cut-off wheel on opposite flats to weaken it followed by chisel in the crack...

Did the nut loosen a tiny bit at first? I'm trying to picture how the blade got loose enough to turn without the nut loosening at all.

Good luck, I don't think I would put that kind of effort into a steel-deck (from your description it sounds yours is a steel deck).

rope in the spark plug hole for 2 strokes has been around forever. Won't hurt anything as long as you don't get it in the ports. Old lawmboys don't have the blade adapter keyed to the crankshaft so when you break the nut loose the blade just spins. Some rope in the plug hole is the solutuon.

All good advice. Here's my plan: 1) use an impact wrench, 2) try to chisel/cut the nut off, 3) use the rope trick as a last resort. I'll tune later today or in a couple of days to let you all know how it went.

Fuzzy: I believe this 10520 Gold-Series is an 'F' engine on an aluminum deck and it has the 3-speed transmission. The deck has no rust, just peeling paint. The other parts such as cables, handles, and wheel adjustments are rusted. I didn't mention that I picked it up from one of my customers for free who said it ran well for him before just stopping (he thought it was the ignition coil). So if I can get it running with minimal cost,,,, cool. If not, I can put it up on CraigsList for parts. Speaking of which, I found a listing in my area that all kinds of LawnBoy parts for $30.00. Just from looking at the pictures, it looks like some of the parts will fit on this mower; the exhaust muffler/plate and mulch plate (I just have the bag setup at the moment) in particular. For $30.00, I think it's worth the chance.

Thanks for the help.

Spray it down with PB Blaster for a couple weeks prior to doing the work on it. As others said, heat and so on....... Might look into that hot wax trick too.


slomo

Thanks, you had me confused when you said the underside was rusted badly. I thought that model should be aluminum, but didn't want to argue. The parts listing sounds good, where did you say you live?

Let us know how it works out!

Good news. I was about to try the hot-wax method; had my torch, candle all ready. Flipped the mower over, and verified the nut was still stuck to the shaft and noticed the square plate and collar was rotating with the shaft also. So I was able to simple grab hold of that with some channel locks and use the socket wrench to loosen the nut. It must've been starting to come loose from the leverage bar I used. After that, the mulching fan and blade came off easily. I has to use a hammer to knock the square plate loose. Had some difficulty with the 3 bolts on the triangular plate and muffler, but with the right size socket and a hammer I was able to get the socket seated properly and the socket wrench took them off without too much resistance. I proceeded to clean out the exhaust ports; I didn't think they looked bad but I am not an expert on 2-cycle. I did make sure the cylinder was covering the exhaust ports and kept a shop-vac close by. Here are some pics if you want to see what I have been dealing with. Obviously, the rusted out muffler needs replacing. It was actually clogged with grass. I'll post pics in a minute. Need to resize them; they are all high resolution.

Wow. That's the worst muffler I've ever seen. I'd say that, besides the muffler, you also need a new collar/plate, blade, and nut. I guess I'm stating the obvious. Twice I've had nuts so tight that I broke the weld holding the collar/plate together trying to pry the blade and collar/plate off (mowers I bought from sales). Now it's religious use of anti-seize and torque wrench - 50 ft-lbf (never an impact wrench for tightening). Doing this, I've actually had a collar/plate FALL OFF the shaft when removing the blade for sharpening!

It's just me, but I wouldn't put that fan back on.

Keep up the good work!

Use an impact wrench without removing the spark plug. Easy job.
Stuffing crap into the spark plug hole just ends in trouble.

FuzzyDriver said:

Wow. That's the worst muffler I've ever seen. I'd say that, besides the muffler, you also need a new collar/plate, blade, and nut. I guess I'm stating the obvious. Twice I've had nuts so tight that I broke the weld holding the collar/plate together trying to pry the blade and collar/plate off (mowers I bought from sales). Now it's religious use of anti-seize and torque wrench - 50 ft-lbf (never an impact wrench for tightening). Doing this, I've actually had a collar/plate FALL OFF the shaft when removing the blade for sharpening!

It's just me, but I wouldn't put that fan back on.

Keep up the good work!

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Totally agree. I wasn't planning on reusing the old fan or blade and probably not the collar/plate or nut if I can help it. Now you now what I meant when I said it was rusted underneath. The deck is pitted from rock and debris, but no rust. Too bad the guy left it sit outside for 2 years. Omaha BTW. Forgot to answer an earlier question about where I am at.

Fish said:

Use an impact wrench without removing the spark plug. Easy job.
Stuffing crap into the spark plug hole just ends in trouble.

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That would've been my first choice if I had one; now I know it is an essential tool to have and will get one.

Nessuno said:

That would've been my first choice if I had one; now I know it is an essential tool to have and will get one.

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I am thinking about one of those battery powered ones.

My brother-in-law has one of those Kobalt ones. The battery switches out to his Kobalt trimmer and leaf blower too. He likes it. But I would have to see how they do mulching heavy spring grass or bagging, and how well it pulls itself doing that. Wonder how long the battery lasts. He lives down in Wichita so the grass doesn't get real thick down there.

Fish said:

I am thinking about one of those battery powered ones.

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Got it running. It ran well for several minutes then started surging to the point of almost stalling completely. I could play with the throttle and it would rev back up, pull itself well, then repeat the surge. I rechecked the compression before starting, got 120 out of it this time. I pulled 5 times, last time I only pulled 3 times and thought it had peaked out; guess not. I verified spark at the spark plug. I did mix 32:1 with low-ash 2-cycle oil from ACE Hardware. I confess, the gas I used was getting old. Also, I did replace the ignition coil with one of the cheap ones off of Amazon. I know others have had this surging problem before and I will do some research. I attached pics of the mower (you can see how the paint peeled and left a white-glue like substance all over the deck). You can see the parts I bought for $30.00 (I already installed a muffler, square plate, blade, and mulch cover that is not included in the pic): 2 plastic carbs, 2 air filter housings, 2 more blades, 1 more muffler (I chose the lightest one to install; figured less carbon build-up), 3 large orange bearing wheels with grease fittings, 1 more square bracket, 2 ignition coils, a whole mess of misc bolts, a primer bulb, a gas shut-off, and other items. I'm going to check the ignition coils with an ohm meter and I may replace the China one with one of these original LawnBoy coils.

But it does run, and when it did, the drive train pulled itself quite well with no adjustments. Need to work on the surging.

Edit: The parts came from 2 mowers. I believe some of those parts are from a Model: 6211 . If anyone can use something let me know. I'm going to keep the extra muffler and the blade that will fit and the ignition coils if they fit. I can't use the other parts.

Cold weather with rain and possible snow flurries coming today/tomorrow. My backyard needed to be mowed. Long, thick Kentucky Bluegrass holding moisture (see pic). I was going to use my 21" Gravely with the Kawasaki FJ180V (converted to push-mower because the plastic gears stripped out), but I thought I would give the Lawn-Boy another chance. It ran flawlessly. Never surged. Good power. Did bog down in the thick grass and even stalled a couple of times when I was trying to go to fast, but fired back up with one pull. If I had gone slow enough in neutral, it wouldn't have stalled. I absolutely LOVE the 3-speed transmission; I was practically trotting behind it in 3rd at times (I went over some of the yard twice) while the 1st gear is slow enough to get through most of the heavier stuff. The deck did get bogged down with wet grass clippings, but it made through okay. I'm very pleased with it. The mulch plate is only held on with the one (butterfly?) screw for now. I need to bolt it all the way down. I think it was part of the reason the side-chute was getting plugged up. I think I mulched the yard more than side-chuted it.

As far as the surging, I'm thinking there may have been some moisture in the tank from when I flushed it and now any moisture is gone. I'm still curious if anyone thinks I should try the used Ignition Modules I picked up over the new Chinese one I bought.

In a week or so, I'll have my 14yr old daughter (5' nothing and <100 lbs) paint it up and I will post a pick. It's actually going to be her mower to make some money (mine was just too heavy for her). I'd like to paint it original LawnBoy colors, but I think she is going to go LA Lakers colors. So you might see a pic soon of a Lakers 2-cycle LawnBoy. (-;

Glad to hear it's running well. Automotive "Grabber Green" is just about the perfect match for Lawn-Boy green, if you can talk her into it. The two bolts you are missing are special shoulder/built-in washer bolts that thread into nylon square pop-in nuts. The threads are the only thing normal about them (1/4-20 NC). If you are careful, you can squeeze the tabs together and push the nuts through from another mower and re-use them in yours.

The 3-speed trans is obsolete and parts are getting expensive. Since it sat outside for two years, you really want to open up the transmission and give it a good cleaning / rebuild.

I picked up 2 3-speed mowers last year (1 $10 / 1 FREE) the 1st one's trans had water in it, but thankfully no parts were worn out ... so I was REALLY GLAD I opened it up, cleaned everything up and re-greased it !!

2nd one was dry inside but had water in it at one point as one gear was corroded and a couple of teeth were bad. The main drive shaft and 2 bushings that ride on it were bad too and these 4 parts were just under $118. It is really strange in that the bushing on the left looks ok, but the shaft is chewed up where it rides. Vs. the bushing on the right is trashed and the area on the shaft where it rides is no where near as bad as the other. The bushings are not that much $$ and if the shaft was evenly worn at both spots I would have saved $84 and done just bushings and reused the shaft. The replacement gear I got was used and was $10~15 cheaper than new. Other areas where the drive shaft can be worn out is at the the end bushings at the height adjusters.

Doug

There's a dealer going out of business that has a new 3-speed Lawn-Boy that he took parts off of years ago. Let me know if either of you live near Toledo, OH and are interested. I could go back and take a closer look. I'm a push mower, AL deck kind of guy, so I didn't look at it very closely. The dealer is a few miles from my house.

I just checked my own stuff and I have a 3-speed Lawn-Boy parts mower which I would be happy to trade for a Walbro carburetor with the whole air cleaner still on it. Heck, I'd trade it for just a decent air filter cover from an F-engined mower/Toro 93-1231!

I was going to pull the tran cover off and look in there and grease the rear wheels. Haven't gotten to it yet, but now I will be sure to get to it sooner than later. I have noticed the mower can be a little difficult to pull backwards, so I suspect a worn part or dirt in there somewhere.

FuzzyDriver said:

I just checked my own stuff and I have a 3-speed Lawn-Boy parts mower which I would be happy to trade for a Walbro carburetor with the whole air cleaner still on it. Heck, I'd trade it for just a decent air filter cover from an F-engined mower/Toro 93-1231!

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Check that parts picture I posted back in post #17. There's an air filter cover in there and two plastic carbs with air filter covers. If you think you can use them let me know. I'll temporarily turn on PM.

dougmacm said:

The 3-speed trans is obsolete and parts are getting expensive. Since it sat outside for two years, you really want to open up the transmission and give it a good cleaning / rebuild.

I picked up 2 3-speed mowers last year (1 $10 / 1 FREE) the 1st one's trans had water in it, but thankfully no parts were worn out ... so I was REALLY GLAD I opened it up, cleaned everything up and re-greased it !!

2nd one was dry inside but had water in it at one point as one gear was corroded and a couple of teeth were bad. The main drive shaft and 2 bushings that ride on it were bad too and these 4 parts were just under $118. It is really strange in that the bushing on the left looks ok, but the shaft is chewed up where it rides. Vs. the bushing on the right is trashed and the area on the shaft where it rides is no where near as bad as the other. The bushings are not that much $$ and if the shaft was evenly worn at both spots I would have saved $84 and done just bushings and reused the shaft. The replacement gear I got was used and was $10~15 cheaper than new. Other areas where the drive shaft can be worn out is at the the end bushings at the height adjusters.

Doug

View attachment 56389

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Got around to servicing the tranny. It looks like it needed it. In one pic you can see that the gearbox doesn't have much grease in it; all the grease came off in the cover pan and it has some golden-brownish grease (rust?). A second pic is after I cleaned out the old grease. The 3rd pic is the new grease (Lucas Red N' Tacky #2); I used a lot of grease because I wanted to finish up the tube in my grease gun; let it squirt out when I tighten on the pan cover and wipe off the excess. I also gave a few pumps into the wheel zerks.

Nessuno said:

Check that parts picture I posted back in post #17. There's an air filter cover in there and two plastic carbs with air filter covers. If you think you can use them let me know. I'll temporarily turn on PM.

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They look good to me. I'd be happy to trade for the 3-speed parts mower I have. Do you live anywhere near Toledo, OH?

FuzzyDriver said:

They look good to me. I'd be happy to trade for the 3-speed parts mower I have. Do you live anywhere near Toledo, OH?

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Omaha, NE. All I'd really be interested in are the tranny parts and maybe the cables. If you stripped them off the chassis and boxed them up, I'd help pay for shipping. I'd send you the green cover and one of the plastic carbs with a cover. I'll keep one for myself, just in case even though my current carb is metal. If that's too much work, I'd still send you the cover. Couldn't cost much just for that.

Well, it's been a year. Old Lawnboy runs fantastic. Best mower I've ever had. I wanted to post some updated pics for you guys. The lawnboy enthusiasts will be mad at the paint job. If you remember, my daughter is a Philadelphia Flyers fan and wanted to use those colors. We did something different. All black with decals. The black paint on the green plastic will peel eventually. I will either touch it up or peel it all off and go green on the deck.

Would like to add, I did something stupid this week. The control cable busted, so I removed the small wire that grounded the ignition coil, just to get it running so I could mow my lawn. It didn't seem to have the power/rpms I am accustomed to. Afterwards, I realized I forgot about the engine brake. I mowed my whole lawn with the brake engaged. No wonder the motor seemed a little hot afterwards. New cable is around $90 bucks and I'm not paying that. I'll need to rig something up with a homemade control cable. Love that mower though. It cut through tall heavy spring kentucky bluegrass better than any mower I've had. The deck would eventually get bogged down, but the motor kept wanting to run; never died.

Nessuno said:

Got around to servicing the tranny. It looks like it needed it. In one pic you can see that the gearbox doesn't have much grease in it; all the grease came off in the cover pan and it has some golden-brownish grease (rust?). A second pic is after I cleaned out the old grease. The 3rd pic is the new grease (Lucas Red N' Tacky #2); I used a lot of grease because I wanted to finish up the tube in my grease gun; let it squirt out when I tighten on the pan cover and wipe off the excess. I also gave a few pumps into the wheel zerks.

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Some lube is better than nothing.

But.... I would of used Snapper's 00 grade grease if it was mine. That tacky red mess doesn't flow at all. Once the initial turning gets done, no grease will be picked up to further lube anything. Grease is a thickened oil. See where this is going? Key here is flow and recoating parts.

You can get this Super S 00 grease at Tractor Supply for 6 bucks. I've used a ton of it, good stuff.



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