Onan RV QG 4000 Mechanical Issue and No Start
6 year old 4kw Onan Spec L. 920 hours (lots of dry camping). Oil, plug and air filter regularly changed, generally 2x annually, along with intermittent oil level checks.
Back late winter, it had an issue where a worn rocker spun 90 degrees on the stud, closing the exhaust valve and dropping the pushrod off the cam. Engine shut down same as being switched off. Apparently bad parts, rocker or nuts, when built. Replaced valvetrain hardware (stud, rocker, adjuster nut and lock nut). Pushrod still straight as an arrow. Bumped starter and all looked good. Valve cover back on and no start, blowing white smoke. Plug comes out wet with fuel, and there is spark to the plug. Did a compression test and only get 95 psi. I know earlier Onans had a compression release system, but I see nothing in the manual that this relatively late model version still does. Do not have a leakdown tester and don't really want to spend $100 on one if I don't have to.
The wildcard here is when I went back into the enclosure to dive into the valvetrain, there was a mouse wandering around in there that may have eaten through something not readily seen from the service door. Kind of hoping that my be the reason for my no start, but all the wiring I believe is on the front of the unit and no obvious evidence of things chewed though.
Before I drop this thing out the bottom of the compartment and tear into it, anything else obvious and easy to get to to check? And speaking of tearing into it, does anyone know if the engine on this is interference? Wondering if somehow when the rocker spun the engine went out of time and bent the exhaust valve.
Back late winter, it had an issue where a worn rocker spun 90 degrees on the stud, closing the exhaust valve and dropping the pushrod off the cam. Engine shut down same as being switched off. Apparently bad parts, rocker or nuts, when built. Replaced valvetrain hardware (stud, rocker, adjuster nut and lock nut). Pushrod still straight as an arrow. Bumped starter and all looked good. Valve cover back on and no start, blowing white smoke. Plug comes out wet with fuel, and there is spark to the plug. Did a compression test and only get 95 psi. I know earlier Onans had a compression release system, but I see nothing in the manual that this relatively late model version still does. Do not have a leakdown tester and don't really want to spend $100 on one if I don't have to.
The wildcard here is when I went back into the enclosure to dive into the valvetrain, there was a mouse wandering around in there that may have eaten through something not readily seen from the service door. Kind of hoping that my be the reason for my no start, but all the wiring I believe is on the front of the unit and no obvious evidence of things chewed though.
Before I drop this thing out the bottom of the compartment and tear into it, anything else obvious and easy to get to to check? And speaking of tearing into it, does anyone know if the engine on this is interference? Wondering if somehow when the rocker spun the engine went out of time and bent the exhaust valve.
