I hit a stump while mowing with the push mower. It now vibrates badly. I guess the shaft is bent. Does it need a new engine or can the shaft be replaced? It's a Briggs & Stratton 3.5 hp.

Thanks

 

Check the easy stuff first - loose bolts or bent blade. I've hit rocks and stumps several times over the years but never did any major damage.

Our small engine pros will be along later

 

You can check if the crank is bent by removing the spark plug, removing the blade and hub (what the blade attaches to), tip the mower on its side, have a second person squeeze the bale (brake) lever and pull on the starter rope. You can watch the action of the crankshaft yourself. The tricky part is to know how much wobble is severe and how much is tolerable. If the mower vibrates and there is no chunck out of the blade then it will still be in relative balance and then you can safely assume that the crank is to blame. Yes, a crankshaft can be replaced but it may not be worth the time and money since cranks are, generally, $50-70 then you'll need oil, gaskets, a seal, and likely a blade. This will put you near the cost of a new 3.5-horse mower since such small horsepower mowers are typically under $100.

 

I don't know about where you live, but up where I live, I can find a perfectly good used push mower for under $50 pretty much anytime. Look around; you don't have to buy a new one.