Have a riding mower with a Briggs & Stratton OHV 14.5hp vertical shaft
motor which makes some rather disturbing "klunking" sounds during
startup and spindown. I'm wondering what the heck this might be. It
sounds fairly normal when running. Any ideas?

Is it electric start or pull rope ?

IF pull rope there are some ball bearings in the part just under the
pull rope and they engage the pull rope clutch to start the engine.
When the shaft starts spinning centrifical force pulls them outward
which disengages the clutch. You might be hearing these bearings as
they are being driven outward. IF electric start it's something else.

J


Dave wrote:
Have a riding mower with a Briggs & Stratton OHV 14.5hp vertical shaft
motor which makes some rather disturbing "klunking" sounds during
startup and spindown. I'm wondering what the heck this might be. It
sounds fairly normal when running. Any ideas?

Oh it's electric start. The "klunking" sounds close to once per rev but
it fades away immediately as the motor gets up to speed.


Joey wrote:
Is it electric start or pull rope ?

IF pull rope there are some ball bearings in the part just under the
pull rope and they engage the pull rope clutch to start the engine.
When the shaft starts spinning centrifical force pulls them outward
which disengages the clutch. You might be hearing these bearings as
they are being driven outward. IF electric start it's something
else.

J

Dave wrote:
Have a riding mower with a Briggs & Stratton OHV 14.5hp vertical
shaft motor which makes some rather disturbing "klunking" sounds
during startup and spindown. I'm wondering what the heck this
might be. It sounds fairly normal when running. Any ideas?

Probably the motor is worn out, a bearing is giving out.

m Ransley wrote:

Probably the motor is worn out, a bearing is giving out.

Or the rod is knocking and quiets down when gets some oil in it and is
covered up by the exhaust noise when it's running...