Small Engines (Lawn Mowers, etc.): seized engine, scott bonnar, briggs and stratton

Question
Hi John

This is my first post and my first mower , so apologies in advance for not
knowing much...

I have a Scott Bonnar 3.5HP 148CC  Lawn Mower - Model 520 (No 047626)

The engine is a Briggs and Stratton 4 cycle engine made in Milwaukee
Wisconsin USA.

I started it up today and after about a minute of mowing the engine seized.

I tried to pull to starter cord and it wouldn't budge.

I then noticed the engine oil was empty so i got some 10W-30 and filled it
(gave it around 300mL / half a pint of oil)

I then took off the top cover and the starter puller assembly and moved the
part of the engine that the puller connects with (fly wheel ?) back and forth
with a screwdriver until things seemed to loosen up.

I was then able to pull the starter again but the (flywheel) seems to stop on
the way around and make a high pitched squeal/squeak.

This always happens in the exact same spot.

Can you work out from this whether is have a bearing problem or worse ?

many thanks

Stevie




Unfortunately , the  

Answer
Hello Stevie:

From your Description it Sounds like the Flywheel Key has Sheared and the Flywheel is Turning on the Crankshaft. The Flywheel Key Times the Plug Firing for the Engine. The Position the Engine Stops is During the Compression Stroke Most Likely. ***Remove the Blower Housing (metal engine cover). Remove the Flywheel Nut or Starter Cup (Depends on the Model). Now Attach a Steering Wheel Puller to the Flywheel Using the Threaded Holes in the Flywheel. Tighten the Puller. Now Hit the Puller with a Hammer. Repeat this Procedure Until the Flywheel Pops Up or can be Lifted Off the Crankshaft. On Some Models you Can Not Use a Puller and Must Use a Pry Bar and a Pipe Cap that is Slightly Larger than the Crankshaft. Place the Pipe Cap Over the Crankshaft to Protect it. Place the Pry Bar Under the Thick Section of the Flywheel and Pull Up Against the Flywheel. **BE CAREFUL  DO NOT PUT A HOLE IN THE BLOCK UNDER THE FLYWHEEL** Now Hit the Pipe Cap that is on the Crankshaft (covered with the Pipe Cap). Repeat the Procedure Until the Flywheel can be Lifted Off the Crankshaft. *** After Replacing the Key, Replace the Flywheel and Torque the Starter Clutch/Cup Nut to 150 Foot Pounds. Reassemble the Components and Check the Blade for Tightness. Usually when an Engine Locks Up the Blade will Loosen and Needs to be Re-tightened. Send me the Model and Type or Spec Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. These are Usually Stamped Into the Blower Housing (metal engine cover) Above the Spark Plug. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John