520H Onan Dilemma

[wh5208speed 645]

So a few years back (Summer of 2015), I stumbled onto a pair of old 520H at an auction. They were used to push snow at a local bank. I am assuming the bank transition to paying to have someone else push snow because these Wheel Horses had been sitting in storage for a very long time. One had about 94 hours and the  other had about 115 hours, both had snow blades and no mowers. I got the 94 hour wheel horse cleaned up and running and ended up selling it to cover the cost of what both tractors cost me. I finally got 115 hour 520H running and it sounded great. About 15 minutes into running it developed a knock, which sounded to me like a rod. I shut it down. So the tractor has been sitting for the past 5 years waiting for me to decide what to do with it. If it was a higher hour machine I would have sold it a long time ago, I just hate parting with something that is in such great shape otherwise.

 

I have been considering a couple of options:

1. Find a Onan mechanic that knows what they are doing and fix it right

2. Buy a new 23hp Vanguard and keep the tractor

3. Keep an eye out for a donor 520H with Low hours (not many of these around anymore)

4. Sell the tractor as is and let someone else have the project

 

I really prefer option 1...but I know these Onan's can be money pits. Anyone know of a good Onan mechanic in the Ohio area?

 

Thanks!

Thad

 

 

[Sparky-(Admin) 21,300]

If indeed the engine is shot I would go with a Vanguard or a Honda conversion. 

[WVHillbilly520H 10,373]

115 hours , I highly doubt anything major is wrong with it... But anything is possible... Could be something as simple as dislodged carbon , valve tappet clearance to big , low oil pressure (did you change oil and filter before start up?)  To more involved like a loose valve seat or rod bearing... IMHO the Onan gets a bad rap they are hard to beat when running right a little finicky yes but opposed twins have more torque than the Vs and nothing sounds quite like an Onan up on the governor singing its song.

[tom2p 2,394]

sheesh 

 

Onan P220 with 115 hours ?  
 

it's barely broken in (or should be)

 

 

 

 

[lynnmor 7,302]

Have someone open it up and investigate, until you you know the damage there is no way to choose the best course of action.  Nothing special about an Onan, it's just another small engine and there are manuals right here to guide you or a mechanic.

[bc.gold 3,403]

Before using the laid up tractor did you check to see if the mice had built nests under the tin shrouds.

[Pullstart 62,785]

Would you feel comfortable changing the oil again and adding some sea foam and running it a bit then draining again?  There should be metal flake in the oil if it’s internal damage.  If it is damaged, what’s done is done...

[peter lena 8,580]

agree with pullstart on the possible oil issue, if it were me i would have slowly heated up the engine with heat lamps to get the oil moving. rislone oil treatments do a terrific job of cleaning and restoring ring gap crud and would help in its basic run in . with the low hours , i would think the engine was ok , mabey a fuel issue or other problem caused its lack of use. somewhere in time, motorcycle shop , regularly recovers and starts 100 year old cycle engines , using the slow heat up way of starting . hope you manage to save that engine , pete

[peter lena 8,580]

sorry gave you the wrong ,shop , it was wheels thru time , https://wheelsthroughtime.com/museum/, i have been there , talk about bringing back the dead , pete 

[Andy N. 2,136]

Option 3 worked for me last fall and I couldn't be happier. I swapped an Onan from a '90 520H into my '89. Not a big deal at all. Kept the original harness and intake manifold/carb. Donor tractors with good engines are out there. I swapped over the forward swept front axle as well so I could use the 60" deck that came with the donor.

 

 

[WildmanC120 613]

Boat anchor that Onan and throw a Honda or vanguard in it and be done! 

[WVHillbilly520H 10,373]

55 minutes ago, WildmanC120 said:

Boat anchor that Onan and throw a Honda or vanguard in it and be done! 

I would agree with you if it had 2115 or more hours but just at 115 it's worth the effort to see if it's just something simple vs a rebuild/replacement.

[Greentored 3,201]

Go with option 2 or 3 and let me take that 'junk' 115 hour Onan off your hands and dispose of it properly.

...right into my 1300 hour 520 after a freshen up

[Skipper 1,788]

If you chose to swap engines, I would go for a diesel....................

[tom2p 2,394]

1 hour ago, Skipper said:

If you chose to swap engines, I would go for a diesel....................

first time I heard an Onan and then used an Onan (416-H) I thought this gotta be the next best thing to a diesel !

 

 

[Greentored 3,201]

14 hours ago, tom2p said:

first time I heard an Onan and then used an Onan (416-H) I thought this gotta be the next best thing to a diesel !

 

 

Ever hear one with a stack on it? You'll find excuses to use it

[Greentored 3,201]

In all seriousness, if youre not anti-Onan and want to get out on the cheap, I just had a thread going awhile back about Onan powered RV gensets. Most would be super low hours, they ran at 1800rpms instead of 3600, and they can be had for a song- like 100-200 all day long, running. They do have a tapered crank, but as a fellow member here posted, theres adapters available. For 3600rpms, just pop half the balls out of the governor assembly.

oh, and paint it black or swap tins, Gawd those puke green gensets were hideous

[bellevillerod 834]

I'm running 4 onan engines over here. That one you have is brand new in comparison to mine. 3 of mine are from the mid 70's. I'd check to see if you have a stuck valve. They do collect a bit of stuff when running but yours are snow machines not cutting grass. Like someone else said check for mice nests. Pop the covers off check valve clearances an run some fresh oil with some k1 an mineral sprites in it. Run an hour and change oil. Love to hear an Onan sing.

[bellevillerod 834]

20 hours ago, WildmanC120 said:

Boat anchor that Onan and throw a Honda or vanguard in it and be done! 

Ya I second that.....right into my lake...I'll do it for you. They get a bad rap because they require some maintenance. Guy's are not used to that anymore. Keep them clean, check an change oil, adjust valves every 18 months. Those engines will run circles around a V. The torque they produce is excellent. Just think of the flat plane engines, they are in super-cars. I grab every one that I come across. Ya parts are getting hard to find, but they are still out there. Take the time to get to know one, you will be better off from the experience.  

[tom2p 2,394]

lol I'm a just little behind on the valve clearance adjustment  ... my 416-H is now at around 1000 hours 

 

without a doubt the best thing / vehicle I've owned - ever 

even if it completely dies tomorrow 

( got another 416-H last summer for when it bids farewell )

 

[tom2p 2,394]

416-H - compared to 312-8 - saves me close to an hour when I cut grass ; minimum 30 minutes 

 

416 cuts high grass with ease - almost imperceptible ... damp and high ? - no problem - motors through at top speed with no bog / no slowing ... 

 

can only imagine what a 520-H would be like 

 

[Andy N. 2,136]

22 hours ago, tom2p said:

first time I heard an Onan and then used an Onan (416-H) I thought this gotta be the next best thing to a diesel !

 

 

 

8 hours ago, Greentored said:

Ever hear one with a stack on it? You'll find excuses to use it

 

How 'bout no stack or muffler. TURN UP THE VOLUME! Love that sound!

[bellevillerod 834]

6 hours ago, tom2p said:

lol I'm a just little behind on the valve clearance adjustment  ... my 416-H is now at around 1000 hours 

I guess I mean just as a check, you can learn about an issue before it becomes a major problem. I do mine, the ones that are being put up for the winter as a quick check about every two years. But I like to tinker on my tractor's too..only had to break out the wrenches and adjust a couple of times. Knock on wood but I really don't have many problems with my Onan's. Biggest issue is they are frigging vacuum machine's, they really suck up the leaves and grass clippings...lol 

[tom2p 2,394]

2 hours ago, bellevillerod said:

I guess I mean just as a check, you can learn about an issue before it becomes a major problem. I do mine, the ones that are being put up for the winter as a quick check about every two years. But I like to tinker on my tractor's too..only had to break out the wrenches and adjust a couple of times. Knock on wood but I really don't have many problems with my Onan's. Biggest issue is they are frigging vacuum machine's, they really suck up the leaves and grass clippings...lol 

 

 

only recently (past few years)  learned the valves should have been adjusted a long long time ago (and now I have a time bomb lol)

 

unfortunately proper maintenance was not performed when I was focused on other areas 

 

but I do clean grass and leaves from the fan intake !

 

at one time mounted a small snow brush on the tractor with Velcro  (right side / belt guard) to enable me to brush away debris with little or no slowing or dismounting 

 

Edited April 15, 2020 by tom2p

[chex313 123]

On 4/14/2020 at 10:31 AM, tom2p said:

416-H - compared to 312-8 - saves me close to an hour when I cut grass ; minimum 30 minutes 

 

416 cuts high grass with ease - almost imperceptible ... damp and high ? - no problem - motors through at top speed with no bog / no slowing ... 

 

can only imagine what a 520-H would be like 

 

The only thing that slows the 520H down is having to fill the tank every 2 hours