# Kawasaki FC420V engine knocking



## RusDAWG1

I have scag walk-behind mower with a 14hp Kawasaki FC420V motor. Recently it started knocking as soon as I fired it up. I have checked the pull starter for any debris. Does anyone have any suggestions?


----------



## ossaguy

I have had several this year that have made knocking noise,and it was from the small trans pulley that's on the crank started rattling and beat itself at the keyway so it was really egg shaped.From a few feet away,it sounded like it was going to blow.but that is a condition that happens over time,not all of the sudden.

Did yours start knocking all of a sudden? Has it had a history of good maintenance,or has it been run low on dirty oil? Along with the con rod,there are 2 counterbalncer con rods that are for the counterbalncer that can get scored with low,dirty oil.Has it seized up recently? It could be the rods gotten aluminum transfer from it,and the bolts are streched and loosened.

That engine also has "The flying Brick",which is what our Kawasaki rep joking said,that happens when the counterbalancer weight goes.We had one come in the shop that blew it right out the back hard enough to break the hardline fitting on the hydro hose ,resulting in a huge oil mess.

Those are my possability-guesses.If you have a mechanics stethiscope,see if you can narrow it down.If it's the counterbalancer,it will be noisy around the rear of the crankcase where the 4 nuts hold on the center support part.It's common to find a spider crack coming away from one of the 4 studs.I've seen 2 that did that,and was coming off the bottom stud.

I hope you can post your results when you discover what it is.

Take care, 
Steve


----------

