Onan Engine Hours

[armstrrw 15]

I am considering the purchase of a single owner 416H. It is a one owner, stored inside, dealer-maintained tractor with mowing deck. I knew him for more than 30 years and he was very meticulous and even polished the tractor regularly. Its appearance is awesome, and it starts without noise or hesitation. Once started, the engine idles well and runs under load (mowing deck engaged) without hesitation or signs of smoke or lost power. All tires are fully inflated, have great tread, and are not dry rotted. The wheels have the chrome hub caps. With the engine running I detected no clicking/ticking/knocking. Steering is tight and hydro system responds well with both transmission and mowing deck. All gauges work along with lights. There is no apparent fuel, oil, hydraulic fluid leaks. The hour meter registers 1091 hours. My concern is should this number of hours of run time be of particular concern? I believe the tractor was purchased between 1995-97.  

[TJ5208 1,824]

I say grab it because my 520-8 has only 826 hours on it. If it runs good sounds good it is good.

[ri702bill 8,320]

Hour meters can be deceiving - if the key were left in the ON position with the tractor off, the hour meter keeps on going, counting up hours.

Bill

[Achto 27,571]

58 minutes ago, armstrrw said:

The hour meter registers 1091 hours.

 

Well maintained that engine should go 2000+hrs

Edited February 5, 2022 by Achto

[Ed Kennell 38,173]

15 minutes ago, Achto said:

 

Well maintained that engine should go 2000+hrs

 

                          Buy it quick.   I would remove the tins and clean the cooling fins and check for oil seepage around the oil filter base plate.

[lynnmor 7,306]

44 minutes ago, ri702bill said:

Hour meters can be deceiving - if the key were left in the ON position with the tractor off, the hour meter keeps on going, counting up hours.

Bill

 

An Onan doesn't work like that, the oil pressure switch turns on the hour meter so hours only accumulate while the engine is running.

 

Onans can run thousands of hours if well maintained.  One such maintenance item is a valve adjustment every 1000 hours, I think that is pushing it when used on a garden tractor due to the varied conditions they are operated, I say 750 is plenty.  Most just ignore valve adjustments and wait till the valve seat burns and destroys the engine.  The Onan engine was developed to power generators where conditions don't vary so much.

[Sparky-(Admin) 21,317]

  I might be wrong but I thought at the 1000 hour mark the Onans were due for a head de-carbon job? 
  Did the seller do that? If not and it is in fact due you might want to see what that will cost you (whether you do it yourself or have a dealer do it) 

[lynnmor 7,306]

9 minutes ago, Sparky said:

  I might be wrong but I thought at the 1000 hour mark the Onans were due for a head de-carbon job? 
  Did the seller do that? If not and it is in fact due you might want to see what that will cost you (whether you do it yourself or have a dealer do it) 

 

Yes, a de-carbon is on the list as well.  I have pulled heads to do that but it was basically a waste of time since they were clean enough.  I run my Onans at a high RPM and that may help keep carbon out, others that putt along may need more cleaning.

[cschannuth 3,816]

I’ve had two Onans and, other than my Briggs & Stratton, they were my most trouble free engines.

[peter lena 8,627]

@Ed Kennell  good call on that ed , reflective of  learned experience , regularly snoop around to keep an eye on things , those manifold gaskets and  other relate  possible  oil issues should have a status check. rather find the start of a problem, than get  stopped with a major shut down . keep  looking  ,and  enjoy your stuff , pete 

[armstrrw 15]

Thanks to all who replied concerning my questions about the 416H. With your inputs concerning the potential purchase, I've made up my mind. A few photos will follow soon.

Bob

[armstrrw 15]

2 hours ago, lynnmor said:

 

Yes, a de-carbon is on the list as well.  I have pulled heads to do that but it was basically a waste of time since they were clean enough.  I run my Onans at a high RPM and that may help keep carbon out, others that putt along may need more cleaning.

The tractor was maintained 100% by dealer since purchase. Owner did keep tractor indoors/covered when not in use and washed/waxed it but all mechanical work was performed by WH dealership. Luckily, one of the mechanics that serviced it still works at the Toro dealership and was a WH mechanic.

Bob

[armstrrw 15]

3 hours ago, Ed Kennell said:

 

                          Buy it quick.   I would remove the tins and clean the cooling fins and check for oil seepage around the oil filter base plate.

Ed, I have completed purchase and will do as you suggest while "winter" is still around. For its age, this 416H is in great mechanical/routine maintenance shape. The owner was a great person, friend, and neighbor ...... he is missed.

Bob

[richmondred01 2,237]

Every onan over 500 hours I planned on keeping, I would take it off the trailer, run it into the garage and pull the engine.

I would pull the heads and valves, decarb, face the valves, new ignition module and replace all the gaskets I removed in the process. 
cheap insurance and good for another 500 hours. 

[lynnmor 7,306]

3 hours ago, richmondred01 said:

Every onan over 500 hours I planned on keeping, I would take it off the trailer, run it into the garage and pull the engine.

I would pull the heads and valves, decarb, face the valves, new ignition module and replace all the gaskets I removed in the process. 
cheap insurance and good for another 500 hours. 

 

 

I too, would go over a used one immediately after bring it home.  I would set the limit higher at 750 hours unless there was some issue.  These things are getting old so gaskets and intake valve seals need replaced.  I bought one of those well maintained one owner 520H tractors that just had a valve adjustment, when I pulled the exhaust for glass beading and paint along with the intake for inspection and carburetor cleaning, I found the valve covers buried in solid debris that was there from day one.  TRUST, but VERIFY.

[Handy Don 12,225]

I have only limited experience with Onan's,  but I agree with @lynnmor and @richmondred01 about preemptive maintenance -- the 700-750 hour threshold works for me.

 

I especially concur about pulling the engine to do the work--that engine truly fills up the front of a WH and the on/off effort was more than repaid by ease of access for the maintenance, being able to closely examine all the bits and bobs, and a chance to do a thorough cleaning not only of the engine but the area behind and. below the hoodstand.

(Important note: these engines are heavy so I highly recommend using a hoist attached before loosening the mounting bolts--the designers put those lift rings on there for a reason!)

Edited February 6, 2022 by Handy Don

[kpinnc 12,028]

Just a note on P-series longevity when properly maintained: 

 

I have a Toro Groundsmaster. It had 2500 hrs on the meter when I got it, and the meter was frozen up. I mowed with it for another 10 years before the 'many times welded over' deck rotted out. It still cranks and purrs like a kitten. I can only guess, but it has somewhere between 3500 and 4000 hours on it. The only thing it has different from a Wheel Horse is an external oil cooler. Still speaks volumes about an Onan in my book.

 

The only negative in my book is the expense that comes with rebuilding one. You can't cobble a rebuild like you can with other engines. Onan specs are very tight. They are precision built engines and a rebuild is not the place to skimp. 

Edited February 7, 2022 by kpinnc

[richmondred01 2,237]

I agree with kpinnc they are great engines. 
Start off fresh and proper cleaning and maintenance and they will last a long time. 
Parts are high. I stopped rebuilding them because of the cost of the parts. 
Gotta love the deep rumble of a p220.