20 hp onan life

[slammer302 2,155]

How many hours should i get out of a motor and is thier any difference in life between a kohler and onan? The WH I'm looking at has 608 hours

[MarkPalmer 81]

An Onan Perfomer twin should last at least 2000 hours if maintenance is done by the book.  The Onan engines differ from the Kohler KT series twins in that they are aluminum crankcase/cylinder construction with a cast iron sleeve insert where the Kohler KT's have solid cast iron cylinders.  This has demonstrated to be a reliability advantage for the Kohlers, as many Onans over time have had problems with their valve seats working loose from the soft aluminum deck surface, a problem that is difficult to repair.  As Onan stopped making gas engines quite a while ago, parts for all Onan built engines are getting harder to find and much more expensive, prompting many with worn out Onans to re-power with other engines rather then rebiuld their old engine.  This hasn't been much of an issue with Kohler as they have had much better company and aftermarket parts support.  The Onans are/were smooth runners and very powerful when working right, but can be an expensive proposition once autumn years set in. 

 

-Mark-

[JackC 617]

It depends on the maintenance the ONAN gets or has had and if it ever overheated during its 608 hours.  An aluminium ONAN performer series engine can fail no matter how many hours are on the clock if it over heats and the block warps or the valve seats come loose.  Mowing with a 42 or 48 inch side discharge deck can cause the flywheel screen to plug up with grass clippings and prevent sufficient cooling air to the engine.  Some grass clippings are blown out of the front of those decks and those clippings get sucked into the flywheel screen.  Grease. grime and glass clippings can also build up on the cooling fins to cause cooling problems.

 

They are great running engines when they run right but they need special attention to avoid overheating and to maintain the valves in adjustment.

Their carburetors also need to be kept clean.

[Farmall A 1]

All good points. My Onan on the 520H has 1470 hours. No major issues in 24 years thank goodness.

[546cowboy 301]

Wait a minute here. Those KT-17's were the worst engines Kohler ever offered until this new Kohler Courage came out ( you have to be courageous to buy one ). I have only seen one out of the four I've owned that didn't have a broken rod and it ran like $%^&. So there was nothing reliable about a KT-17. Let's get that straight while you are comparing.

 

I have owned 6 Onans and yes three of them were bought with valve seats out. It's not that expensive to repair them if you have a good machine shop locally. 608 hours is pretty good for a tractor that could be up to 25 years old.

Edited June 20, 2013 by 546cowboy

[MarkPalmer 81]

Wait a minute here. Those KT-17's were the worst engines Kohler ever offered until this new Kohler Courage came out ( you have to be courageous to buy one ). I have only seen one out of the four I've owned that didn't have a broken rod and it ran like $%^&. So there was nothing reliable about a KT-17. Let's get that straight while you are comparing.

 

I have owned 6 Onans and yes three of them were bought with valve seats out. It's not that expensive to repair them if you have a good machine shop locally. 608 hours is pretty good for a tractor that could be up to 25 years old.

 

Yes, the original KT series I engines were extremely troublesome with rod failures when used on slopes, fortunately most of them hit the scrap piles decades ago and I would avoid a KT series I twin at any cost if one happens to surface.  I replaced one of these in my Cub with a Honda GX, luckily before the KT had a chance to blow up.  These were the failure on Kohler's part that put the Onan Performer twin on the map.   With the pressure lubed Series II KT twins though, the Series I oiling problems were solved and these engines stand up very well, plus they are easy to rebuild with good parts support, and there are gobs of them out there running still.  I should have pointed this difference out in my first post, I just assume there aren't any Series I KT's left to bother anyone, but there are still a few kicking around that weren't used on slopes.   I have priced recently what would be needed to fully refurbish an Onan Performer with machine work, and it would be around $1300-1500 to put one back in shape the right way.  I can put together a Kohler Series II KT for about half of that. 

 

-Mark-