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I just bought a used Craftsman push mower with a Briggs and Stratton 6.75hp motor. I got it home and was mowing the backyard when accidentally mowed over some metal enclosure lining around the garden area. The blade penetrated the metal lining and caused the blade to stop, which quickly killed the engine. It wouldn't start after that.

Upon dis-assembly I found not only was the flywheel key cut in half, but the flywheel itself has a crack. I am assuming I will be needing a new one, but wanted to make sure first. If this one will still work I will continue to use it. I have pictures below. If I do need a new flywheel, does anyone know the part number or where to get one? What is a reasonable price for one? All I can find as far as a part number on the flywheel is "17M", but a google search for that brings me nothing of use. The blade on the mower itself is not bent or damaged.

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We will need the model, type and code numbers off the engine. They are stamped on the engine shroud. It looks like a standard Briggs flywheel and you should be able to find one reasonably. Get us the numbers.

I am guessing that the one is pictures is no good by your response.

Here is the numbers that I've found on the shroud.

SAE J1940

126L02 1080-F1 08040456

FAMILY: 8BSXS.1901VZ E11*97/68SA*2004/26*0706*01

Thanks for the help!

Flywheel part number is 691987. For safety reasons you should never use a damaged flywheel.

Forgot to add,,, Have your parts place double check your numbers before ordering.

I don't have a parts place, is there somewhere that you recommend going to? What is a decent price for one?

Check smallenginewarehouse.com. That flywheel shouldn't be anymore than fifty bucks. I would think you could have it shipped to your house for that cost. There should also be a sticker on the deck somewhere with craftsman's parts line if you wanted to deal with them. I have always found another way around other than using them.

Any small engine dealer, even many tractor dealers, should be able to help you. Most are authorized B&S dealers. The reason I would like you to go this way is that if I gave you the wrong part number, or you get shipped the wrong part, you have some recourse to get your $$$ back. If you have to have it shipped from an online source, use a phone call to verify you are ordering the correct part.

Thanks for the help guys. I got a used flywheel for $20.00 and a key for $1.00 at the local mower shop.

I put it on, replaced the flywheel key, and even put some new oil in it. For some reason it still won't start. Doesn't even sound like its getting close to starting when I pull it.

Any suggestions?

Sublime said:

Thanks for the help guys. I got a used flywheel for $20.00 and a key for $1.00 at the local mower shop.

I put it on, replaced the flywheel key, and even put some new oil in it. For some reason it still won't start. Doesn't even sound like its getting close to starting when I pull it.

Any suggestions?

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Back to basics, timing, spark, fuel, compression, and it will run.

Did you set the armature air gap to .010"? If not no spark!

Damaged Briggs & Stratton flywheel

My son is rebuilding a Briggs and Stratton 3 HP (horizaontal shaft) engine as his HS Senior Project. While trying to remove the flywheel, I broke off one of the small fins (it's a flywheel / blower cast unit). As a project only, and not for continued use, I'm wondering what the result will be if it is reassembled with that flywheel. I assume it will vibrate more than normal, and perhaps the bearing surfaces will get more abuse, but I'm thinking it will run and be fine to demonstrate that he has learned how to disassemble and reassemble a working small engine.

Any comments?

Thanks,

Larry

Re: Damaged Briggs & Stratton flywheel

lrcrabtree said:

My son is rebuilding a Briggs and Stratton 3 HP (horizaontal shaft) engine as his HS Senior Project. While trying to remove the flywheel, I broke off one of the small fins (it's a flywheel / blower cast unit). As a project only, and not for continued use, I'm wondering what the result will be if it is reassembled with that flywheel. I assume it will vibrate more than normal, and perhaps the bearing surfaces will get more abuse, but I'm thinking it will run and be fine to demonstrate that he has learned how to disassemble and reassemble a working small engine.

Any comments?

Thanks,

Larry

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Over the years I've put them back on without noticing any vibration or had any trouble with
them from only one fin broken off. Now if the keyway was wobbled out I wouldn't use it, or if the flywheel cracked diagonally. Not safe as the flywheel could literally fly apart! Very similar to what would happen on a grinding wheel that had a hairline crack in it.

One fin off will not cause any noticeable vibration or a problem.

That will be the last photos I ever view through Image Shack . I really don't care to listen to a commercial the remainder of my life . I finally had to close all tabs and get completely out of Lawn Mower Form to get the bastards to shut up . Ridiculous .

Do you see why it cracked ? The idiot engineir put the key way at the weakest point, the key way corner in close proximity to the hole .

Re: Damaged Briggs & Stratton flywheel

lrcrabtree said:

My son is rebuilding a Briggs and Stratton 3 HP (horizaontal shaft) engine as his HS Senior Project. While trying to remove the flywheel, I broke off one of the small fins (it's a flywheel / blower cast unit). As a project only, and not for continued use, I'm wondering what the result will be if it is reassembled with that flywheel. I assume it will vibrate more than normal, and perhaps the bearing surfaces will get more abuse, but I'm thinking it will run and be fine to demonstrate that he has learned how to disassemble and reassemble a working small engine.

Any comments?

Thanks,

Larry

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I would break another fin off on the oppisite side of the flywheel

I definitely would not try to balance the flywheel by breaking a fin on the other side. Fins are there more for cooling, not balance, and in my opinion you will be teaching your son the wrong thing. In this case two wrongs will not make it right, and the balance will not be far enough off to create a problem with one fin off.

I do agree, but he mentioned that this only needs to run to show he assembled it to running condition. With an unbalanced FW, depending if it is aluminum or cast, could vibrate a lot. Overheating shouldn't be a problem with such a short run time.

As a retired teacher I have to say it again, don't break off another fin. I have had students break a fin off more than once. That one fin on an aluminum flywheel will not cause an major vibration. We have run many engines with this condition with no problems. The student may even want to use the engine afterwards. Students learn from their mistakes and this can be a teaching moment for both the instructor and the rest of the students. Being truthful with the instructor and explaining that you thought about being unbalanced and the way to correct it, will go a long way in showing him what you have learned. I'm sure he has already learned a lot by reading this forum. I'm sure glad to see his father is teaching him the right way.

The only time I ever had a fin break was as a kid working on an old Briggs model #N Hor shaft with a cast iron flywheel. The vibration was "very" bad, unacceptable, and unsafe. This was on an old reel type mower and the vibration would surly have eventually thrown the critical bedknife to reel out of adjustment. I broke the fin on the other side and things were smooth once again. I would say that this is more evident with a cast iron flywheel vs an aluminum one. I have "seen" engines come in to my shop with aluminum FW's that ran smooth and later I'll find a fin missing. With the model N, and with 2 fins missing, it never ran hot and I mowed with it for years then L used that engine on a go cart also for years. Just this simple experience has shown me that no harm was done to that engine and because of that lack of out of balance vibration, it lasted for years. I don't see any safety hazards doing this.