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Small Engines (Lawn Mowers, etc.)/mtd push mower oil leak at bottom


I have a 22" Bolens  push mower 6.5 hp. I noticed oil under it when I moved it, raised the mower up and the bottom of I guess the motor  and blade are greasy ,checked the oil it is very black. what is my problem and how to fix it, the mower runs great , just the oil leak when parked,
   thank you,

It may be the lower main seal leaking.  You should check for sure and see if anything, like fishing line or string, is wrapped about the crankshaft and seal area.

To check, DIS-CONNECT the spark plug wire FIRST.  Tilt the mower so the spark plug is facing UP, towards the sky.  Now you should be able to safely check to see if the seal is leaking.

If so, the seal will need to be replaced.  It's not that hard but you need a couple of special tools to remove and install.  I have a homemade tool to puncture and remove the seal and a piece of PVC pipe with a cap to install a new seal.

BEFORE removing measure how far the old seal sits inside the engine block.  Too deep or too shallow can cause a new seal to leak.

It is very important to clean and sand the crankshaft before installing a new seal.  The shaft needs to be shiny and smooth.  Once the shaft is prepped carefully slide seal onto the crankshaft and use the PVC tool to install the new seal.

Have you checked You Tube for videos?


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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