Snagged a 520H

[608KEB 794]

I bought the 94 520H that was listed on Red Square classified. Very happy with it. 350 hours. 48" SD deck. Should get years of use out of it. I have 93 520H with 980 hours. It is in fair to good condition. I can't decide if I should keep it for parts or sell it. It seems I've heard more bad than good things about Onan 20hp motors. I think the 93 520H tractor would be worth about $750-$850 with the 42" RD deck and mule drive. Feel free to post good stories and bad nightmares about Omen motors.....I mean Onan. I am curious.

[AMC RULES 36,945]

Omen...I like that...    

five two zero...the new number of the beast. 

[varosd 1,185]

Wow!  Looks brand new for a 1994!!

 

your 1993 should be kept.  always good idea for a back up!

[Sparky-(Admin) 19,538]

I think its a good motor but it needs more attention given to it than a Kohler. It should never be allowed to overheat/run hot! I also think if I owned one I would be installing the vented beltguard so that the heat from the rear cylinder could blow freely away from the motor.

I think someone on here was making a vented beltguard.

Mike..............

[KC9KAS 4,741]

Very nice looking tractor!

Thanks for the photos.

[chazm 412]

SWEET 520 TRACTOR  !!!!!   

 

Chasm  

[608KEB 794]

I saw the vented belt guard in a post about 1 1/2 years ago. I could be wrong but I thought someone posted not to change the airflow pattern. Is that why the valves go bad? do they overheat or something?

Edited January 11, 2014 by 608KEB

[JackC 616]

I would keep both and use the 93 the most to see how many hours you can get out of it.  As long as it does not overheat you should get 2,000 plus hours out of it and you will never be down with carburetor problems because you will have a back up ready to go.

 

You can use that gorgeous 94 to ride to church on Sundays.

[608KEB 794]

2000 hours!?!?? really. I look through posts and on you tube and don't here stories like that. That's encouraging!

Edited January 11, 2014 by 608KEB

[boovuc 1,090]

Very nice looking tractor!

 

Remember something about the internet and forums in general. Most people will post bad things about a person place or thing before they will go out of their way to post being just plain "satisfied" with a person place or thing.

It's just the way we humans are wired.

 

Onans have a knack for a few things that can cause some problems but overall, they are a pretty good engine. If they weren't...............we wouldn't be talking about them except in reference to their past existence. You never hear anyone say that they are "going out to feed their Tyrannosaurus Rex". They may say something like "man I wish I would have been around when a Tyrannosaurus Rex used to crap in the yard".

 

We use these Onans and many of them are between 20 and 30 years of age. If they were crappy engines, this conversation on this forum wouldn't be happening. 

Now if we were talking about the wiring on the Onan powered 400 and 500 series tractors........................      

[pj1960 11]

I have only had one Onan engine a CCKA cast iron twin in an 817 Gravely. High dollar to work on but purred like a kitten with lotsa power. Mine was a great engine but I dont know about others.

[JackC 616]

I think the issue with the ONAN Performer Series engine is that if you are not careful with them, they can overheat and lose a valve seat or rod.  Some people hate the ONANs due to the cost to rebuild them  I would not rebuild.  I would just look for another used engine.   I just bought a used 1989 520H with a 660 hour ONAN for $450.

 

Here is an example of a post from someone with a 1500 hour ONAN:

 

I have a 1988 520HC Wheelhorse purchased new with over 1500 hours and have had only a couple of minor engine problems. When new I had a couple of leaks repaired under warranty and last year the regulator/rectifier had one of the fast-on tabs burn off. It uses only 1 pint of oil in 50 hours. Onan parts are expensive. The biggest problem with Wheelhorse tractors is lawn debris collecting on the engine blower inlet screen causing overheating. If you do regular maintenance, oil & filter changes, keep air filter clean, and valve adjustments it will last a long time. I do not use my tractor in the winter so I add StaBil to the fuel. I also use Chevron Techron Fuel System Cleaner, a 12 bottle divided between 2,5 gallon cans of fuel each year. The Techron will not only help clean the carburetor but also disolves the oil carbon on the intake valve stems.

[JackC 616]

The ONANs have way more torque at lower RPM.  Here is part of a post that gives an example:

 

"The other reason I went with the Onan was I demoed a unit with one a few years prior and thought it had tons more torque than another unit with a same hp Kohler Command (able to engage pto at idle with Onan with 60" deck where anything less than half throttle would stall Kohler w/48" deck).

So far, the only parts I've used in 50 hours have been two oil filters that I purchased from NAPA at no more cost than the ones for my old Kohler. "

[BOWTIE 226]

THAT IS A GREAT LOOKING TRACTOR. TAKE CARE OF THE ONAN AND IT WILL TREAT YOU WELL.

[Wheel-N-It 2,967]

JayInNC was making the belt guards.. Send him a PM.

Good score on the 520. I may get around to repowering mine some day, but I doubt it will be with an Omen. I will probably try something more V-twinish.

[Dieselcowboy 210]

Onans are used for industrial instead of kohler. There must be a reason. Could you imagine if a refer or gen set failed how much $ would be down the tube? They must be reliable. In those apps there is not grass or bad wiring to deal with.

[shorts 182]

Onan engines are as good as any other air cooled engine when they were developed and initially manufactured. Like any other engine they have their particularities, in different applications some engines work better than others, Onan's mounted in WH long ways seems to create a cooling problem with the rear cylinder due to grass buildup on the fan screen as well as in the tins, in a D series or something painted another color with the engine turned cross ways grass build up and cooling don't seem to be as much of a problem so you have to ask yourself is it the engine design, the tractor design or a maintenance issue or a combination of things?  the opposed twins run smooth and quiet for a long time in a fixed rpm application particularly in power generation, that being said if you run your Onan at WOT 3600 rpm and let the governor control the throttle the engine and hydro trans will last a long time with proper maintenance.  Also remember that the good running engines get very little recognition , they just keep on running.

[HorseWhisperer 243]

That 520 is the ultimate sweetness.I feel bad for the guy that  parted with it.

[cheesegrader 433]

I love my 520's.  I have had some electrical gremlins, and they use a LOT of gas, but they are beasts!

Air flow across the rear cylinder is blocked by the guard over the drive belt.  Like all safety features, I am sure this was added late in the design.

The front cylinder has nothing blocking the air flow.  The front cylinders never throw valve seats.

I wouldn't modify the tins that direct air flow to the fins on the rear cylinder, and I would be very fussy about keeping leaves and grass out.

This is what I have done to my belt guards.  3/4" step cut drill bit and a drill press.

LOTS of heat comes through these holes, most of it off the upper half.

[Brownta 5]

I bought a 1992 520-H several years ago. It had just under 200 hours on it. I'm up to 535 now with no issues at all. My grandfather also had one, and he had it up to 1400 hours with no issues. When he passed away, I sold it to a guy from Australia. So I can't speak for what happened to it after that.  Our local dealer says he sold a lot of these back in the day, and as long as the oil is changed on a regular basis (HD-30 in the summer and 10W-30 in the winter) and the air intake screen is kept clean while mowing, these are solid 2000 HR engines. We have this exact same engine on a welder at work. It has 2300 HRS on it and we have never had any issues with it. The valve issue seems to come from the screen getting plugged while mowing and the engine overheating. When the engine gets to a certain temp, is my best guess on why the valves warp. The neat thing about the Onans over the Kohlers is the tube that runs from the fan to the air intake chamber. The fan forces air into the chamber, almost acting like a tiny supercharger. I have heard many people say and write on here that this Onan is more powerful the the 22hp Kohler in the newer 522xi/Lxi's. Don't get me wrong, I love the Kohlers, they seem to be almost indestructible to a certain extent. But I love the unique sound and power of these Onan motors.

 

I love the holes in the belt guard Cheesegrader. That looks like a simple after work project that I bet helps out a ton and will save a few Onans and 520's along the way. I see so many of these starting to get parted out. Makes me sad because there just isn't anything that compares IMO.