Briggs engine popping

[StarTech]

This one of the engines that Briggs had to redesign the flywheel and crankshaft. They issue a service bulletin on on it.

Two things were done to help resolve the shearing.

• Change the flywheel key to a steel one. Both on the old style and new style.
• Increase the flywheel retainer torque to 110 ft-lbs. Service manuals still list the old torque value.

Note I have seen at one flywheel on these to be busted where they meet the crankshaft.

 

[Omacrulzzz]

There was a burnt spot in the belt like you said. I put on a new belt and it seems tighter but still vibrating. I found a broken spring . It's the little spring that attaches to the idler. I looked at a diagram and it says it's the spring return idler. The idler shakes back and forth when the blades are engaged. I'm gonna get a new spring. Do you all think a broken spring could be responsible for the vibration?

 

[Omacrulzzz]

There was a burnt spot in the belt like you said. I put on a new belt and it seems tighter but still vibrating. I found a broken spring . It's the little spring that attaches to the idler. I looked at a diagram and it says it's the spring return idler. The idler shakes back and forth when the blades are engaged. I'm gonna get a new spring. Do you all think a broken spring could be responsible for the vibration?

I just replaced that idler return spring. It helped a little with the vibration. Still looks a little shaky to me, but the new blades, new belt, and new spring all seemed to decrease the vibration. Not sure what else to do at this point. I have another mower with a briggs engine and I cranked them up at the same time yo compare. The vibration doesn't look too significantly different I think.

 

[bertsmobile1]

There was a burnt spot in the belt like you said. I put on a new belt and it seems tighter but still vibrating. I found a broken spring . It's the little spring that attaches to the idler. I looked at a diagram and it says it's the spring return idler. The idler shakes back and forth when the blades are engaged. I'm gonna get a new spring. Do you all think a broken spring could be responsible for the vibration?

No
All that the return spring does is to pull the idler back off the belt so it does not get damaged & the belt has no tension so it can slip on the engine pulley .
If the idler is bouncing then something is changing the tension and usually it will be a bit of crud stuck in the V of a pulley.
Bits of branches get caught then flattened down into the V and are hard to see.
However if you remove the belt and lay a long screwdriver in the V so it touched the pulley about 1" back from the tip of the blade then spin the pulley, and crud will cause the screwdriver to skip.
Some pulleys are made in 2 pieces riveted or welded together and these halves can split apart and that is also hard to see .

 

[Omacrulzzz]

No
All that the return spring does is to pull the idler back off the belt so it does not get damaged & the belt has no tension so it can slip on the engine pulley .
If the idler is bouncing then something is changing the tension and usually it will be a bit of crud stuck in the V of a pulley.
Bits of branches get caught then flattened down into the V and are hard to see.
However if you remove the belt and lay a long screwdriver in the V so it touched the pulley about 1" back from the tip of the blade then spin the pulley, and crud will cause the screwdriver to skip.
Some pulleys are made in 2 pieces riveted or welded together and these halves can split apart and that is also hard to see .

Ok. I'm gonna check that tomorrow before I crank it up again. I did have to clean crud from under the pulleys, but I didn't think to clean the v in the pulleys. Maybe I'll luck out and there's a pebble or piece of wood jammed in there. Thanks.