Hi Folks, my mower needed help. The belt was worn out and no longer self propelled. The belt needed changing. I could not figure out an easy way to get it off and back on. I checked the internet and Youtube. Finally I found a fifteen year old kid doing the same thing and posting his video on Youtube. So here is an additional resource to help someone accomplish the task.
V belt at the engine, quite oily and worn
First, you need a new belt. I had the old one off, measured it, and bought one at ACE Hardware. My wife threw away the cover which had the numbers on it so the receipt is all I have. The ACE # is 22524, but what will likely be more help is the size printed on the receipt. The V Belt is listed as a 3/8″ x 32″ which seems awfully long, but belts are measured from start to finish along a point so this one is only 16″ in radius and only 3/8 inch thick a very small belt. I took the one From ACE but ordered one as well from a Lawnboy dealer. The price 3.99 versus $20 plus shipping of estimated six bucks. I also replaced the muffler a whopping $70 because it had a one inch by three inch hole in it. Also replaced the blade adaptor, no small feat. Okay, I looked it up at ACE it is a 3L320, indeed a 3/8 by 32 inch FHP, fractional horsepower belt. Click this link: to go to ACE. Hope this helps you get a belt without paying the Lawnboy order price, I got one of those just in case. $19.95 and shipping instead of six quoted, was 12.95, so my spare Lawnboy belt, I may need in 25 years was $33. But this has been a great mower and I have no regrets spending that little extra. Someone told me they no longer make the 4HP OMC engine air cooled, but have gone to other makes of engine like Briggs and Stratton, Honda, and Kohler, all good engines but not the OMC, which stands for Outboard Motor Corporation. These Lawnboys were outboard motor engines, putt putt putt! Cheers and have a great life! bd
Okay, here are the steps best I remember it from the task two days ago.
1. Place a baggie over the fuel tank opening and put the cap back on to stop fuel spillage.
2. Turn off the fuel at the bottom of the tank.
3. Lay the mower on it’s side and remove the blade, 15/16″ socket or wrench.
4. Remove the blade adapter, it is wedged on the tapered shaft of the motor and has no keyway. Likely it will require a gear puller, mine did. Sometimes heating the tapered collar and banging on it with a hammer may help loosen it. Until you get this adapter off you can go no further, it’s a must. My adapter was broken so the square plate had come off the tapered collar, so I simply pulled on the round collar, tightening and banging on the puller screw pushing against the end of of the crankshaft of the motor. POP, off it came. I won’t lie to you, this is the hardest part.
5. Next you will remove three half inch bolts holding on the muffler.
6. Next take off the four bolts holding the motor to the deck plate. The deck plate is about eight inches and you will find two bolts at the exhaust port, and two either side of the crankshaft port. This will allow the engine to come off the mower. (I first removed the plate using three bolts and nuts holding the deck plate in position) (that was a mistake) ( the belt is sandwiched between the deck plate and the motor) (So you will end up removing the deck plate from the engine to get the old belt off)
7. I found the drive crankshaft pulley loose and sliding around on the crankshaft. It has a small screwdriver slot to tighten the set screw in the pulley. Most pulleys tighten with an allen setscrew, but not on Lawnboy, they have a straight screwdriver slot. Mine was frozen in place. I theorized that it was working before the belt went bad, and that it would continue to work even with movement up and down the shaft. I considered drilling out the screw and ruining the pulley, but getting it off and allowing me to replace it, but I decided to leave it and my guess was right, it works still. Hopefully yours will be stationary like it’s supposed to be. It works, at least for now. Do what makes sense to you.
8. I put the ACE Hardware belt on, just to try it. It too, worked. It was no easy task aligning the belt and getting it into position while bolting the deck plate back on. Just keep working with it and finally all will align and bolt up. Leave the belt loose from the driven pulleys as you won’t be able to get the motor mounted with tension on the belt. The final step is putting the belt over the largest transmission pulley, then threading the other two. By doing the smallest tensioner pulley last, which is flat not V shaped, you will have the tension all in one place. You can pull it over the edge of the flat pulley, and turn the motor with either the starting rope or by hand turning the larger transmission pulley. It will go over the edge and into position, but you will have to man handle it. Fingers are your best tool, you don’t want to damage that belt. It’s one of those brute force jobs. It will be a relief once you get that belt on. Take a break and clean your hands.
9. Reinstall the muffler using three 1/2 inch bolts.
10. Install the blade adapter and blade using a 15/16″ wrench.
11. Next for me was a crank up the mower and test the next day, before putting the cover back over the pulley system, on my unit two screws. One long one that has a phillips head, I used a small straight screwdriver on this to get under my commercial tank. It’s a recessed location, but accessible to you. My screw was buried under leaf mulch, but I found it and got it out. The other smaller screw is also phillips or 3/8 inch. I used a socket an three inch extension, and ratchet on the easy one. You’d think they would be the same screw but they are not.
There you have it in a nut shell. It is not a job for the faint at heart. It is a very doable job, the hardest thing being a puller to remove the blade adapter. You may be able to rent one from a parts store? I had one from other work done in the past. Good luck to you. I hope you find this on wordpress.com. I find stuff comes up in the search engines from wordpress fairly quickly.
serial number and model, identify this as a 1986 on the lawnboy.com website
An old fellow, a machinist, told me that any two cycle engine would last longer, if you just doubled the amount of oil in the gas. I tried it and could hardly breathe through the cloud of smoke on my lawn as I mowed. I went back to the factory recommend. And, here 27 years later I’m still using this mower, every week in the summer.
My old Lawnboy, an 8481 rear bagger, commercial, with high capacity fuel tank, self propel. You’d be hard pressed to find a mower this good nowadays. That’s why I decided to fix it.
Link to a kid on YOUtube doing the tail end of this job, replacing the belt. Just shows that you must remove the engine, blade, blade adapter from the shaft, muffler, and aluminum deck plate from the motor to get to the belt. It’s worth a look if you are doing this on your Lawnboy. His is the standard Lawnboy. Mine has the large tank above and to the rear, his has a shroud tank. Click here to see Meitzler’s belt replacement. Way to go Nathan.
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