Bad sound below 1000 rpms

[wm frech]

...just launched my B281 and Perkins M 20 engine sounds excellent above 1000 rpms but loud and vibrating below 1000 rpms...phone call to mechanic and he says may be dirty injectors...would appreciate any comments from readers...thanks.

 

[Bill]

Same here

I also have a Perkins M20 in my 281. It starts and runs great (fires right after sitting thru winters) but at low idle it runs rougher that when over 1000 rpm. Since I only run it below 1000 rpm when leaving or entering the slip, I don't worry about it.I think most diesels tend to idle rougher than gasoline engines.