edgcooper 12 #1 Posted September 10 Recently aquired a 1994 520 H. How often do you owners of the Onan 16, 18 and 20 hp engines pull the heads to remove carbon? Adjust valves ? Share this post Link to post Share on other sites
lynnmor 7,951 #2 Posted September 10 I have pulled heads at roughly 1000 hours and there wasn't enough carbon to matter, but I work mine at full throttle. If you bought used there is no way to know how it was treated and if it uses much oil, then for sure pop a head and take a look. While Onan says to adjust valves at 1000 hours, I suggest that you do it at 750 because of the varied use that a garden tractors has. These engines were initially designed for generator use and were run at 1800 or 3600 RPM. 2 Share this post Link to post Share on other sites
ri702bill 9,698 #3 Posted September 10 I know it's not much use on a Kohler single cylinder engine, but would a borescope be helpful on an Onan?? Share this post Link to post Share on other sites
lynnmor 7,951 #4 Posted September 11 5 hours ago, ri702bill said: I know it's not much use on a Kohler single cylinder engine, but would a borescope be helpful on an Onan?? It would be helpful on any engine but quite often it is difficult to see all surfaces. Share this post Link to post Share on other sites
