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Non running 520 H how bad can it be?

43 posts in this topic

ID: 1   Posted

A guy wants to sell me a 520 H that has not run since last fall.

Cranks but will not fire on ether.

No spark condition. Should be something simple.

But if not, how much could it cost me to fix an electrical problem?

The price is attractive for these parts.

Thank!

Joe

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ID: 2   Posted

first DON'T use ether on small engines, use carb or brake cleaner, I use brake clean all the time, well if the price is right buy it, but parts for the Onan can be pricey, if it cranks you probably have a ign. issue, first thing to check is if you have 12v at the + side of the coil with the key on, if no figure out why? start with the key switch, if yes, you will have to start trouble shooting the ign. parts.

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ID: 3   Posted

if it cranks with the switch but wont start and you are getting fuel it would probably be the ignition module [ trigger ] or the coil so check onan parts.com or flea bay to see what the parts are running but if the price is right buy and worry about fixing it later parts will only run around $100.00 but i would run a compression check on both cylinder to make sure it don't have a blown rod or a bad valve seat, but if cheap enough it is still worth it just for part by the way what year is it and does it have the swept front axle ?

eric j

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ID: 4   Posted

It's not the cost of the parts that kills you with 520 electrical problems, it is the time to figure everything out.

I just spent $130 on coil/condensor/plugs, but it took HOURS to fix all the crazy wiring the P.O. did to bypass broken safety switches.

Nothing makes me want to poke out my own eyes like electrical problems.

I have two 520's, and as much as I love them, I swear I will push them into the lake if they have another major electrical failure!

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ID: 5   Posted

One of the weak areas of the 520 is it's fuse block. Failing most frequently is the connection to the 30 amp fuse. Grass and moisture sits there and causes corrosion. An open is similar to operating without the battery connected in that there is no load on the engines regulator. Most people are aware not to operate the engine without a battery but don't realize that an open 30 amp fuse is similar to no battery installed. An intermittent connection there can take out an expensive regulator.

This isn't likely causing the no-start issue but it is something to pay close attention to.

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ID: 6   Posted

Thanks guys,

I haven't seen this tractor yet.

In will see it tomorrow.

Looks to be in good shape but very dirty.

The guy selling it dosn't know what engine it has in it.

I think I see a swept front axel. Mower deck seems good.

I had a bad cell phone connection. And, could tell there just wasn't any point in asking

Detailed questions. He wouldn't have any answers.

I'll give a through once over. Perform some simple tests for compression, spark and fuel.

And go from there.

Looks like the fuse block could be a problem. But no real big money electronic modules or anything like that?

Thanks,

Joe

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ID: 7   Posted

the swept forward front axle is worth it, I know I would jump on it, been looking for one at a decent price but havent found one yet

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ID: 8   Posted

Hi Joe

is this the guy in Newbury MA with the posting on Boston CL? From the pix, it liiks like a pretty good catch. No rust that I can see, seat not even ripped and it does have a swept front axle. Could be a diamond in the rough. I considered it as well but decided against it. Need to save my $ for an FEL (if I can find one).

Good luck

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ID: 9   Posted

Doc724,

It was in West Newbury.

It's in my driveway now!

Joe

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ID: 10   Posted

Here's some pictures of my latest acquisition.

Had to travel through three states to get (nearly 36 miles!).

No spark, missing a screw on the exhaust cover and some rust on the hubcaps.

But I think it will clean up nice!

It's a 1990 with a 48" deck

post-8342-0-95906900-1359824223_thumb.jp

post-8342-0-85206100-1359824241_thumb.jp

post-8342-0-31568000-1359824262_thumb.jp

post-8342-0-83133600-1359824288_thumb.jp

post-8342-0-23966900-1359824304_thumb.jp

post-8342-0-24422700-1359824321_thumb.jp

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ID: 11   Posted

looks like a decent tractor. hope you get it going without too much work.

yes, i think that would clean up real nice......

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ID: 12   Posted

Who did you buy that from? Im in contact with a gentleman for a package deal- 2 520's, a 417, and a 310, all non runners but look clean

Sent from my 416-8

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ID: 13   Posted

A great catch! It would have been 90 miles one way for me to even go and give a look. Then I would have need to arrange transportation.

Post some pix after the clean -up

Don

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ID: 14   Posted

Looks like it is in pretty good shape, and the deck looks to be in great shape!

Clean it up and hunt down that electrical gremlin, and you will be very happy.

The swept axle allows for the 60" deck, and helps if you ever add a loader.

I don't think gear reduction steering was added until the '91 model,

so you will get a little arm workout if you add a 2-stage blower or any other heavy front-end attachment.

Enjoy!

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ID: 15   Posted

Looks like you found a nice one. Let us know how you make out on the electrical issues.

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ID: 16   Posted

The original owner passed away. And I bought this off a young guy that was selling for the heirs.

It was the only one he was selling.

He had cleaned up somewhat. And put a new battery and terminal ends in it.

He told me it ran fine last fall.

I think he may have connected the battery backwards and fried the ignition module?

I jumped pos to coil, and, still got no spark. So, I took the coil out and brought it into the house to warm it up for testing.

It was very low on crankcase oil. The oil pressure light was blinking. I added a half quart of oil but the light acts the same.

Manual say it has an oil pressure cut out switch. But low oil level won't kill the ignition circuit?

Thanks for your comments!

Joe

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ID: 17   Posted

It's not the cost of the parts that kills you with 520 electrical problems, it is the time to figure everything out.

I just spent $130 on coil/condensor/plugs, but it took HOURS to fix all the crazy wiring the P.O. did to bypass broken safety switches.

Nothing makes me want to poke out my own eyes like electrical problems.

I have two 520's, and as much as I love them, I swear I will push them into the lake if they have another major electrical failure!

Let me know which lake you push them into. I'm a scuba diver and an electrician. Will be glad to salvage them!!!

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ID: 18   Posted

First, make sure the coil is wired to agree with the diagram below (note where the condenser is hooked to the positive terminal - opposite what you may have seen on Kohler coil based ignition systems.

f98f2420.gif

Check the resistance of the coil primary winding

onancoilprimarymeasohms_zps1f4e2d7f.gif

With everything assembled correctly, crank the engine and monitor the negative terminal with a voltmeter or test light,

The test light should flash as the engine cranks (the voltmeter should swing between 1 volt and 13 volts).

It is the transition from high to low voltage that triggers the ignition coil to spark.

015afc6e.gif

676fe03e.gif

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ID: 19   Posted

Soi,

Wiring looked good. I don't think it had ever been apart before.

I took the coil out and brought it into the house to warm it up.

Tested it with both analog and digital volt meters and, it tested good.

I'll test for pulse from the ignition module today.

Check the four fuse block, and the nine pin connector more.

Perhaps test the coil with plug and wire.

Thanks!

Joe

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ID: 20   Posted

This may be of some help to identify the ignition trigger as a go / no go

the current drawn from a 12 volt circuit by the tail light is about the same as the onan coil draws during normal operation.

One Caution - DO NOT TOUCH THE IGNITION BLACK MODULE LEAD TO 12 VOLT POWER AT ANY TIME. IF NO LOAD (lamp or ign coil) IS PRESENT IN THIS LEAD THE MODULE WILL BE DESTROYED.

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ID: 21   Posted

Well, I tested the coil again this morning and, although the primary coil tests good, the secondary coil did not give me a reading.

I tested it, it was bad. I tested it, it was good. I tested it, it was bad! Two out of three wins!

So, I tested it with a spark plug and wire and no go.

I will be ordering a coil and ignition module. Hopefully by the time I get parts the temps will be above freezing!

Joe

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ID: 22   Posted

May I ask how much? It looks like a nice clean machine and sounds like once the electrical issue is sorted out that it will run fine.

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ID: 23   Posted

Great info on the 520's of what to look for. I'm picking up my first one on Wednesday. Im a little nervous after reading through this post. The one I'm buying is a 93 with 900 hours on it. Should I be nervous about one with this many hours on ? It looks like it was shedded its entire life. Looks pretty clean one owner...

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ID: 24   Posted

I've heard Onans are good for 2000 hrs. if well maintained. I have owned 5 of them but none of the ones I've owned had over 1000 and a couple were not well maintained. One had a broken rod and 1 smoked pretty good. Those two I was able to find used engines for. I have also bought two Onan's with the valve seat loose and that is a relatively easy and inexpensive fix. The real problem is from owners who store them outside, that's when you have the electrical problems. But if the price is right you can't go wrong with a 520H.

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ID: 25   Posted

I have also bought two Onan's with the valve seat loose and that is a relatively easy and inexpensive fix.

I thought if the valve seats on these Onans came loose the engine was toast. How did/do you fix them? I've got two Onans in 520H's - that would be good info to know.

Thanks,

Bill

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