Onan Engines


LawnSite Member
Newtown ct
How many people have had Onan Engines that have had good luck with them? I looked at a Bunton ZTR that had a Onan Engine on it (replacement) and the owner said that he had nothing but trouble with any other manufacturers and swore by his Onans. Thanks Turfguy.

John DiMartino

LawnSite Silver Member
I have a pair of Onans,one is an 20hp and the other is a 24hp.I have had the 24 for 5 yrs,and the 20 for 11 yrs.I use to think they were not that good,I had to replace a couple ignition coils,and the 20HP gets bad carbon build up,so bad i removed the heads and valves to clean them.Ill tell you this they are way better than my Kohler command 25-but that isnt saying much i guess.If I had a choice i wouldnt buy Onan again,even though mine have been basicaly good to me.I will give Onan this,the 24hp,has more power at 3000 than the kohler 25 does at 3770-like comparing a big block to a 6 cylinder.


LawnSite Bronze Member
Spring Hill, FL
A few years ago everyone around here (central FL) had a TORO 616 or 620 with an Onan engine. Just about everyone I knew that had one sooner or later had a valve seat pop out. Usually around 1000 - 1200 hrs. Very expensive to repair and usually didn't last long after the repair. I no I'll NEVER buy another.


LawnSite Fanatic
I had a 1986 JD 318 w/ 50" deck. It had an 18 hp Onan horizontal opposed twin flathead. It has over 1700 hrs on it and never had a head off. Granted it doesn't have 18 hp now, but it had oil changed every 25 hrs. My Dad still uses it every week that I can't get to his lawn and he is just now contemplating replacing it with a new 20 hp Onan or whatever will fit. I offered to pay 1/2 of the cost of it. Can't see any sense in replacing it with a Kohler 20 something hp engine. The Onan has an odd size front shaft that will make any substitutions difficult. The flathead design is old, but it had gobs of power for the first 1000 hrs. It was never in the shop for anything other than a starter. I don't think Onan is in the engine only business anymore. Just generators, I think.



LawnSite Senior Member
SW Missouri
I had a Toro 616 with a 16 hp Onan. 1053 hours broke a rod.
Local dealers wanted over $1,000 to short block it. i found new 20 hp Onan online for $575 complete. Slapped it on. I sold the mower last year. He runs it daily without a problem.