Help with Briggs 500e series 140cc repair (Craftsman M100 push mower)

[folksnake]

After 23 years of trying, I finally managed to run a mower into the heavy bronze water shut off at my curb. The mower (and I) lost. The blade shattered the bronze water valve cover, the engine stopped cold, the air filter blew off and after I restarted, the engine ran erratically, very loud and bogged down with even a little bit of grass to cut.

The engine model is a B&S 09P602-0137-F1. DOM 06/01/2020 Ser # 2006011148371.

I pulled the flywheel and the key was a little deformed, so I replaced it. Not a lot, but it did have a crease in it. Replaced the blade too, while I was at it. Put it back together and it runs, but it is very loud and runs way too fast. Lots of vibration translated to the handle--not pleasant. I manually adjusted the engine speed using the linkage and even though I can slow the RPMs down to about where it should be, it's still shaky and too loud at that speed. Something's still wrong for sure.

What should I look at next?

Thanks--

 

[Richard Milhous]

Check for bent crankshaft.

 

[folksnake]

Thank you! Was afraid of that.

 

[artemjemmy]

If it is in fact a bent crankshaft, find the high point of the bend shaft with the mower on its side (oil dipstick side down) and use a good sledge hammer to straighten it out. Some people hate this but I have never had a problem. Note that you will never get it perfect with this method, but you can get it good enough so that it won't noticeably vibrate.

 

[folksnake]

Definitely bent. I've managed to get it back *close* to straight again. Running much smoother now (duh).

But it's still running at high RPM. I can adjust that by bending the linkage, but that seems like a cheat. Something else must be responsible for the high idle.

What would be likely suspect(s) for that?

 

[folksnake]

If it is in fact a bent crankshaft, find the high point of the bend shaft with the mower on its side (oil dipstick side down) and use a good sledge hammer to straighten it out. Some people hate this but I have never had a problem. Note that you will never get it perfect with this method, but you can get it good enough so that it won't noticeably vibrate.

Miraculously, I had an length of heavy pipe that fit right over it. Whaled on it a bit and it came 'round.

 

[Richard Milhous]

Probably something got jammed or disconnected when the air filter blew off. Which I've never heard of.

 

[folksnake]

...when the air filter blew off. Which I've never heard of.

Not a good sign

 

[slomo]

If it is in fact a bent crankshaft, find the high point of the bend shaft with the mower on its side (oil dipstick side down) and use a good sledge hammer to straighten it out. Some people hate this but I have never had a problem. Note that you will never get it perfect with this method, but you can get it good enough so that it won't noticeably vibrate.

And will deform the bearing material and kill the lower seal. Hope you meant remove the crank from the block first.....

 

[artemjemmy]

And will deform the bearing material and kill the lower seal. Hope you meant remove the crank from the block first.....

Have you ever actually done this? I have never had a problem bending crankshafts with a sledgehammer. OP just did it and his mower is fine! Lol!