Navig8r 132 #1 Posted January 26, 2014 My 416 has about 500 hrs on it. It was my Grandfathers machine, and most of the hrs were with him running it... he always kept a small whisk-broom with him to brush grass off the intake, and would brush it off after mowing.... I helped with seasonal maintenance, and things were pretty much always put away clean. My uncle also used the machine a bit (10 hrs?) more recently, and I'm sure there was no maintenance with that usage. I have had it in storage for about 2+yrs,(It was running fine when I put it away) and plan to put it to work in the spring... mainly hauling firewood and dirt around my place, but possibly some mowing. I plan to clean everything thouroughly, change fluids, plugs, filters.... Any other suggestions? I have read here and on other sites of modding the belt cover to improve airflow to the rear cylinder... anyone have any pics? Thanks in advance for any help! ~T.J. Share this post Link to post Share on other sites
motox25 36 #2 Posted January 26, 2014 I'd recommend pulling the shroud and cylinder covers and cleaning them out, it is a pain but usually there's debris that gets trapped there. Also check to see if yours has the rubber air seal around the oil filter, the 2 onans in the 520s I've owned were missing them and this also helps improve airflow to the rear cylinder. Share this post Link to post Share on other sites
AMC RULES 36,954 #3 Posted January 26, 2014 Louvered belt guards are claimed to help airflow around the Onan rear cylinder. Member JayinNC has been making them in the past. Share this post Link to post Share on other sites
wheeledhorseman 573 #4 Posted January 26, 2014 I have a 316 with the same engine but the cheaper version with no oil filter - it's still going strong after well over 1000 hours. There's a lot about the Onan 16 hp on this site and Onans in general but from what I've read the 16 hp is less prone to the typical heat failures like valve seats coming loose which certainly seems true in respect to mine. After 500 hours you should really check and adjust the valve clearances but I found that mine were only a tiny bit out after 1050 hours. It's well worth cleaning out the grooves and recesses in the engine and head castings (as has already been mentioned). I didn't find it clogged up but there was an accumulation of fine grass clipping dust that had got quite thick in places. On the matter of heat issues I always let mine idle and cool down a bit for a minute or so before switching off. I also read about increasing the air flow by modifying the belt guard but haven't got round to this yet as it's probably not as important with the 16 hp Onan. Hope this helps a little in putting things in perspective in terms of my experience. I did post an overhaul I did with pics to solve a hunting issue may provide a bit of background reading for you just for interest sake. Andy 1 Share this post Link to post Share on other sites
boovuc 1,090 #5 Posted January 27, 2014 After you take the engine tins off and make sure they are clean, buy an air tank and a cheap compressor. After doing anything with the machine and in particular, after mowing, blast air through the air shroud and around those tins to keep the grass from accumulating. This and a vented belt guard and keeping your oil changed are the best defense against overheating an Onan. Share this post Link to post Share on other sites
cheesegrader 433 #6 Posted February 3, 2014 Like this? These are 3/4 " holes. Most of the heat comes through the upper part of the vent. If you have a foot control pedal on that side, you might want to adjust the pattern to avoid a "hotfoot". Share this post Link to post Share on other sites
