5.0 horsepower briggs and stratton makes a loud knocking sound

[chevyman984]

Hi everybody, I'm so sorry it took me so long to get up on here, we had a real bad storm up in nelson county and knocked out power for 5 days. And after the power came back on, the phones and internet was down for several days too. Also dealing with insurance tha wont pay fora big oak tree that fell over on my suburban. So yeah sorry. And thank everybody for the help!! And I was joking so I knew you werent being rude lawnranger

 

[ampman]

Mine knocked on startup too. About 6 knocks!
1. Disconnect spark plug lead.
2. Tilt mower back to work underneath.
3. Clamp vise grips on crankshaft above blade mount.
4. Grab vise grips and blade and work blade back and forth.

Any play? Mine had about 1/2 degree of play. I tightened up the blade mount bolt and the knock went away. I put on a new blade and blade adapter last year and it loosened up. I will use some of the strong type of thread locker. Sometimes a damaged blade adapter is the problem. Checking for play is the diagnostic tool.

 

[Mower Doctor 78006]

On MTD push mowers you have a blade adapter with 2 aligning pins built in it for the blade to ride one. The MTD's also have a strap with the 2 locating pins in it. If you install the blade with out the strap it will shake, and vibrate. It the blade adapter has been damaged it will shake and vibrate. If the blade has hit things the adapter is usually gets broken or makes the blade loose and shake.

Mine knocked on startup too. About 6 knocks!
1. Disconnect spark plug lead.
2. Tilt mower back to work underneath.
3. Clamp vise grips on crankshaft above blade mount.
4. Grab vise grips and blade and work blade back and forth.

Any play? Mine had about 1/2 degree of play. I tightened up the blade mount bolt and the knock went away. I put on a new blade and blade adapter last year and it loosened up. I will use some of the strong type of thread locker. Sometimes a damaged blade adapter is the problem. Checking for play is the diagnostic tool.