Small Engines (Lawn Mowers, etc.)/Flywheel Key


I own a McCulloch 3818 chainsaw and I need a replacement flywheel key to fit my machine.  It is a half moon style.  I did not hit anything hard to cause the key to brake, when I replaced the key the first time I bought it from a lawnmower dealership and the gal put several keys on the countertop and said here pick from these. I found one that was a close to the one that was broken.  But after installing it into the chainsaw and used it for less then 5 seconds it broke as well.  The chain turns freely and I have never abused my saw or equipment.  It is hard to find McCulloch parts for a Mac 38.  Thank you for your time.

Something is very wrong with the saw...I have never seen a McCulloch chainsaw or weed trimmer shear a flywheel key and I have worked on thousands of units.

The 102164 McCulloch part number is available at several site for $10...too much money.

I'd take the saw to you local hardware store, as many other sites mentioned, and find the correct size.  Ace Hardware usually has a very good selection of small items like woodruff keys.

Is there a washer under the flywheel nut?  

I would also get some lapping compound and lap the flywheel to the crank taper to make sure the parts are mating correctly.


Small Engines (Lawn Mowers, etc.)

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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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