Engine rattles from idle to ~80% power?

[WheelHorseSteve 56]

So I've been asked to try and diagnose what might be going on with a Kawasaki 17hp vertical shaft running my father in law's tractor. It purrs at full throttle but rattles / sounds sickly at lower RPMs. I'm guessing that something connected to the engine is vibrating, but am a little concerned that it may be internal.

Has anyone experienced anything like this? I have a 21hp Kawasaki on my Scag and have never experienced this. The 17hp has low hours (less than 300) ... I'm hoping it is something superficial.

:thumbs:

[mavfreak 11]

I have a very old 8hp briggs (early 70s) But I have had a vibration even a rattle at low rpm to mid rpm. A friend of mine who is a little better with engines than I said it sounded like a valve. Because of the age I just let it go. Still running many years later. The rattle is louder when the engine is cold and almost unnoticeable when at temp. This is on an old Montgomery wards rototiller.

[Sparky-(Admin) 23,209]

I would start by looking at the motor mounts first.

Mike..........

[WheelHorseSteve 56]

Thanks guys! I'm going to exhaust all the exterior options before seeking further help. Could valves or the crankshaft be noisy at low RPMs and not high? (is this typical?)