Looking at a toro 520H

[WHX?? 51,865]

The nine pin has always been problematic on Onans. Mostly in the  one or two pins pins that see a large amount of current. Add some resistance  to these pins from the crud and you get heat which can actually melt the plug together. Yes start by a good inspection and cleaning. Fortunately  the plug and pins are available for replacement. I have some tractors come through where the plug is eliminated completely.

 

Another weak spot iS the fuse block on the upper right side of the hood stand. The 30 amp fuse circuit can do the same thing as the nine pin and can melt so check that. The 30 amp fuse circuit powers alot so that maybe where your power loss is. That fuse block can be replaced as well but is a real job. There are covers made to keep dirt and water out of it. 

https://wheelhorsepartsandmore.com/product/fuse-block-cap-wheel-horse-logo/ 

https://wheelhorsepartsandmore.com/product/fuse-block-replacement-67-7160/

 

There are some really good wiring diagrams here for 520's so use your shout out if needed. 

 

On the motion lever I may not be able to help you out as all my 520's have been converted to pedal kits. Does sound like an adjustment issue. Check the linkages from the motion lever all the way through the tunnel to the cam plate. The tunnel can look quite busy due to all what's going on in there. I re-bushed with oil lite bushings on a few of the levers and linkages in there as Toro used the cheap plastic ones when built. This too is quite a job but as long I was in there installing the pedal kits. 

Edited February 8, 2022 by WHX??
speeling

[Handy Don 14,124]

 These are all good points for working through 520 glitches.

 

As for the motion lever, if you step back and mentally go through all the linkages and movements needed to translate the column lever rotation to the few degrees of rotation at the hydro cam you begin to appreciate the level of detail needed to assure correct operation. A little slop here and there and then it's not doing what you want. As you get the hang of how the linkages play together and how to adjust them, you'll home in on the good balance. 

The good news is that once it's dialed in, it tends to stay dialed in!

[squonk 43,918]

On an Onan do your self a favor, Check the tightness of the bolts holding the PTO side bearing plate on the engine itself. I had a 520 running in my driveway as I swept out my garage. Went to back the tractor back in and there was over a quart of oil on the ground. Oil everywhere. All of those bolts had loosened up. Some a full turn. If that happened whilst I was out snow blowing I would have had a small boat anchor.

[WHX?? 51,865]

4 minutes ago, squonk said:

All of those bolts had loosened up.

Really??? That would be a new one on me Sqoonky. 

 

22 minutes ago, Handy Don said:

needed to translate the column lever rotation

Agreed Don then throw in the return to neutral & parking brake mechanisms very busy. Once you get the gist of what's going on in there Stegs not too terrible to service. 

[lynnmor 7,848]

My , yes, that 9 pin used on many tractors, and not just Onans, is often the cause of the problem you mentioned.  I'll add some more and that is the ignition switch and its connector and the relays with their connectors.  You can test the relays by swapping connectors between them, and the ignition switch by jumping the wire to the ignition.

 

 

See that large hex plug at the top of this photo?  The main jet is in there, removing the plug will drain the carburetor.

 

The newest of the Onans have the accelerator pump behind the cover held on with the three screws, you may or may not have that but it is a place to look if you have performance problems.

 

While on that photo, you will see two welch plugs just above the accelerator pump.  The larger one can fall out causing extreme surging, the smaller one covers the idle mixture adjustment to keep the EPA happy.  The official repair was to throw the carburetor away.  The older carburetors did not have the pump and did have an idle mixture screw that could be easily removed for cleaning.  I doubt that you have issues there but if you still have problems and need to pull the carburetor, use this for future reference.

 

 

[RED-Z06 2,582]

6 minutes ago, lynnmor said:

My , yes, that 9 pin used on many tractors, and not just Onans, is often the cause of the problem you mentioned.  I'll add some more and that is the ignition switch and its connector and the relays with their connectors.  You can test the relays by swapping connectors between them, and the ignition switch by jumping the wire to the ignition.

 

 

See that large hex plug at the top of this photo?  The main jet is in there, removing the plug will drain the carburetor.

 

The newest of the Onans have the accelerator pump behind the cover held on with the three screws, you may or may not have that but it is a place to look if you have performance problems.

 

While on that photo, you will see two welch plugs just above the accelerator pump.  The larger one can fall out causing extreme surging, the smaller one covers the idle mixture adjustment to keep the EPA happy.  The official repair was to throw the carburetor away.  The older carburetors did not have the pump and did have an idle mixture screw that could be easily removed for cleaning.  I doubt that you have issues there but if you still have problems and need to pull the carburetor, use this for future reference.

 

 

Whats behind the smaller one?  A screw/needle?

 

Nevermind i see its where the screw is on mine.. thought it was some adjustment id never seen before

Edited February 8, 2022 by RED-Z06

[stegs 327]

1 hour ago, lynnmor said:

My , yes, that 9 pin used on many tractors, and not just Onans, is often the cause of the problem you mentioned.  I'll add some more and that is the ignition switch and its connector and the relays with their connectors.  You can test the relays by swapping connectors between them, and the ignition switch by jumping the wire to the ignition.

 

 

See that large hex plug at the top of this photo?  The main jet is in there, removing the plug will drain the carburetor.

 

The newest of the Onans have the accelerator pump behind the cover held on with the three screws, you may or may not have that but it is a place to look if you have performance problems.

 

While on that photo, you will see two welch plugs just above the accelerator pump.  The larger one can fall out causing extreme surging, the smaller one covers the idle mixture adjustment to keep the EPA happy.  The official repair was to throw the carburetor away.  The older carburetors did not have the pump and did have an idle mixture screw that could be easily removed for cleaning.  I doubt that you have issues there but if you still have problems and need to pull the carburetor, use this for future reference.

 

 

 

 

Ill take a better look tonight. My issue isnt all that bad, just some surging at upper rpms. Idle to mid throttle its super smooth.

 

Last time i just took the top off, hit it with some carb cleaner (top/bottom half) and all those little needles/jets

 

I never even looked for this plug. and if that has the main jet behind it, im going to bet that is where my issue is with higher rpms. 

 

Will look into tonight and report back. Thank you gentlemen!

[Handy Don 14,124]

2 hours ago, stegs said:

I never even looked for this plug. and if that has the main jet behind it, im going to bet that is where my issue is with higher rpms. 

 

Just to be clear, the main jet is fixed so don't look for an adjustment behind that screw-in plug--only some dirt. And as noted, opening it will empty the bowl so be ready to capture that gas.

[stegs 327]

21 minutes ago, Handy Don said:

Just to be clear, the main jet is fixed so don't look for an adjustment behind that screw-in plug--only some dirt. And as noted, opening it will empty the bowl so be ready to capture that gas.

 

 

yes. But it could be clogged or obstructed.

 

Im going to drain it, clean it with carb cleaner and maybe some compressed air 

 

 

[squonk 43,918]

The 9 pin connector is also near the heat of the muffler. On my 520 I tore that all out, lengthened the wires from the dash  and moved that connection to the OTHER SIDE of the tractor. Used 2 HD 4 wire connectors to do it. (9 pin has 8 wires in it)

[pfrederi 18,708]

1 hour ago, squonk said:

The 9 pin connector is also near the heat of the muffler. On my 520 I tore that all out, lengthened the wires from the dash  and moved that connection to the OTHER SIDE of the tractor. Used 2 HD 4 wire connectors to do it. (9 pin has 8 wires in it)

  I note a 520 user comments that relays and their connections are also problem areas .  Why I do not use relays on fuel pumps..

 

My , yes, that 9 pin used on many tractors, and not just Onans, is often the cause of the problem you mentioned.  I'll add some more and that is the ignition switch and its connector and the relays with their connectors. 

[WHX?? 51,865]

2 hours ago, squonk said:

The 9 pin connector is also near the heat of the muffler. 

Good point Squonky... one of mine was ther but another was tucked down behind the rear jug.  Guess it depended on what was goin on on the assembly line that day. Odd thing here is Stegy is that with the four that I have all seem to have their own differences and quirks. 

[stegs 327]

Update for all

2/9/22

 

Last night after work and getting a quick workout in, i got the 520 in the garage, had the heat on and radio blasting. Finally, some time to work on it

 

First thing i wanted to tackle was the carb issue. Took it apart again, this time, I removed the float. 

 

Once I got the float out, I could see my issue. Lots of crap in the bottom of the carb. Some varnish, but lots of stuff that does not belong in the carb. Was worse on the main jet side of the carb too

 

So, floats out, took off the choke linkage and removed the drain plug (what a fantastic idea) Took a little brush and carb cleaner and went to work. I got it as clean as i could. I got the air compressor out and gave each little hole a shot of air.

 

I even made extra sure the main jet was clear. Multiple shots of carb cleaner and compressed air!

 

once that was done, reinstalled the linkage and focused on the top of the carb. The top looked fine, everything was clear and working great

 

Reinstalled everything, it fired after a few cranks and ran good. I did not try any full throttle runs as i was in the garage, but i feel fairly confident the junk in the bottom of the carb was my issue

 

 

next job, 9 pin connector. Took it apart, hit it with compressed air, then inspected it. No burning, some corrosion. About what I expected. Hit it with some crc electrical contact cleaner, and then compressed air.

 

Did that about 3 times to make sure i had it clean. Applied just a touch of dielectric grease to each pin and reconnect. Fired up the tractor and everything works.

 

 

I did not have a chance to really test either fix....however atleast i got time to work on it last night

 

 

Yesterday, on my lunch break i picked up a like new ohio steel 50" wide commercial lawn sweeper. My oldest son (who is almost 5) is obsessed with tractors/machinery so he was all excited about the sweeper

 

So, once I got the tractor pretty much done, he told me to get the sweeper in the garage before it snow, and we MUST CLEAN IT SO ITS READY TO GO WHEN THE SNOW MELTS 

 

 

So i spent the next hour helping him clean a lawn sweeper, washing it, checking the solid rubber tires and explaining to him multiple times how it works

 

 

 

Didnt get as far as i wanted, but if your kids show interest in working on stuff, its is time well spent.

 

 

 

Tonights agenda. New fluids and filters. 

 

Side note, found out why my trans is a little slow going forward. Checked the hydro oil level and it was low, like barely on the dipstick.

 

So tonights hydro oil drain and refill should be beneficial 

 

 

Will update after tomorrow after it gets new fluids

 

 

Side note again, thinking about converting the front lights to par36 LED headlights. easier on the electrical system and brighter. May stop and pick up those lights tonight on my way home, or oder them on amazon

 

Edited February 9, 2022 by stegs

[Horse Newbie 7,395]

Thanks for the update ! 
Good stuff…

[WHX?? 51,865]

4 hours ago, stegs said:

My oldest son (who is almost 5) is obsessed with tractors/machinery

Not a durn thing wrong with that far as we're all concerned! 

 

Don't forget to check that fuse block... same treatment as the 9 pin. 

Edited February 9, 2022 by WHX??

[stegs 327]

53 minutes ago, WHX?? said:

Not a durn thing wrong with that! 

 

Don't forget to check that fuse block... same treatment as the 9 pin. 

 

 

Will do. Ill take a peek at that tonight, but I want to focus on new fluids/filters tonight. 

[ohiofarmer 3,379]

On 2/7/2022 at 2:24 PM, SylvanLakeWH said:

 

Ohio…? Ohio…?

 

Oh yea… that’s down south of Heaven somewhere isn’t it??? 

 

We gotta increase our southern border guardin’… (not that southern border) 

 

 

[ohiofarmer 3,379]

i was wondering how thick the ice is and the guys are catching some fish in Sylvan Lake?

  on the  filter stuff and for  just about any other topic like that, the project farm guy  develops tests to the best of his ability .from vice grips to windshield wipers to maybe even filters. I seem to remember derric from VGG splain' about different quality levels available,even within brand product lnes.  My wheel horse filters are not a problem with the K series unless it has an auto trans

Edited February 9, 2022 by ohiofarmer

[stegs 327]

Update 2-10-22

 

last nights focus was on all new fluids and filters. After work, I started up the 520 and let it run for about 10-15 min to get the fluids warm

 

Backed it into my barn and went to work. First on the list was the engine oil. Pretty simple task with the drain the way it is on these tractors

 

as that is draining, went to the back of the tractor to start draining the hydro

 

Little more involved, the drain plug was partially covered with the plow on. No big deal, just drop the plow from the rear brackets enough to get a allen wrench in there.

 

 

within minutes, both oils are draining out. Went inside to have some dinner.

 

 

Came back about 45 min later, both are drained completely. Removed old filters, filled the engine (note to self, next time get the longer filter) Little tight, but it worked fine. About 1.5 quarts in the engine

 

hydro system took a little more time. Left the filter off a few turns to help vent. It didnt go bad, just a little slower.

 

 

After it was reading full on the dipstick, i started it up and let it idle for about 5 min to start moving fluid thru the system. After the warmup, I took it for a drive up and down my driveway** 

 

Forwards/backwards multiple times, all at half throttle.

 

No leaks, everything is working great. Plow lift up and down. No issues at all

 

 

** now is when it gets interesting. I backed up my concrete driveway towards the house. I hit that slight bump in the concrete where my tractor always dies when trying to plow

 

Guess what!!! IN that same spot, it dies again. Dead. No power. No electrical

 

 

I dont know if i have some geo magnetic field in that exact spot, or just terrible luck, but there i sat dead in the water

 

 

Checked all my connections at the 9 pin. Everything looked great. checked the battery cables, they look fine. 

 

Checked all 3 fuses in the fuse block, all of them are fine. Sat back down on the tractor, hit the key and it fired right up

 

 

So, I have determined that I have a bad connection in the fuse block, or i have a faulty ignition switch.

 

Im leaning heavy on the fuse block as the switch seems to be fine whenever i start the tractor

 

 

So, tomorrow I have a half day at work. I plan on spending the afternoon in the barn where its warm and looking at the fuse block

 

That has to be my issue. I dont know what else would make me loose all electrical when i hit a small bump. It has to be a loose connection, because it will fire back up no problems.

 

 

Any tips on removing those wires from the fuse block to clean them? Do i need special tool? I think ill remove them 1 at a time, clean them up and reinstall with dielectric grease.

 

 

There is my update. Still working out the last bugs in this thing. 1 step at a time. 

 

 

 

 

 

 

Side note, never got above half throttle when I took it out, but it seems to be running smooth, so I think my carb issue has been resolved!! (fingers crossed)

Edited February 10, 2022 by stegs

[lynnmor 7,848]

Your engine should take 2 quarts.

 

Raise the front of the tractor to drain the transmission more completely.

 

With the short oil filter perhaps the rubber grommet is missing, I use only Onan 122-0800 or Fleetguard LF3339 filters.

 

If a bump kills the ignition, maybe the seat switch is at fault.

[stegs 327]

24 minutes ago, lynnmor said:

Your engine should take 2 quarts.

 

Raise the front of the tractor to drain the transmission more completely.

 

With the short oil filter perhaps the rubber grommet is missing, I use only Onan 122-0800 or Fleetguard LF3339 filters.

 

If a bump kills the ignition, maybe the seat switch is at fault.

 

 

I ordered the short filter on accident so that may be why it took 1.5 -1.75 quarts

 

The hydro fluid is all set. 

 

The seat switch has been bypassed with new connectors and wrapped in heat shrink to seal the connections.

 

Im leaning more and more towards this fuse block. Im reading alot of this, seem to me ordering a fuse block upgrade is im my future. Im going to look at it tomorrow and try to clean the conections. However, i think to eliminate this issue is to do the upgrade with the heavy cables and better connections. 

[WHX?? 51,865]

2 hours ago, stegs said:

Any tips on removing those wires from the fuse block to clean them? Do i need special tool?

They can be a son of a gun to get out and yes a special tool is helpful. If they appear to be melted in you will not get them out. Do not try. 

Down at the starter there is a smaller wire on the same post as the heavy starter wire. That smaller wire feeds power to the whole tractor back up thru the nine pin and back up to the fuse block so check that connection point. 

Don't forget to check all grounds. 

Here's a nice color diagram that may aid you in chasing down that gremlin. 

Tractor 1991-97 520-H Wiring DM Color (1).pdf

Edited February 10, 2022 by WHX??

[lynnmor 7,848]

1 hour ago, stegs said:

Im leaning more and more towards this fuse block. Im reading alot of this, seem to me ordering a fuse block upgrade is im my future. Im going to look at it tomorrow and try to clean the conections. However, i think to eliminate this issue is to do the upgrade with the heavy cables and better connections. 

You can get a fuse block at AutoZone and they are even cheaper at other places like RockAuto.

[stegs 327]

2 hours ago, WHX?? said:

They can be a son of a gun to get out and yes a special tool is helpful. If they appear to be melted in you will not get them out. Do not try. 

Down at the starter there is a smaller wire on the same post as the heavy starter wire. That smaller wire feeds power to the whole tractor back up thru the nine pin and back up to the fuse block so check that connection point. 

Don't forget to check all grounds. 

Here's a nice color diagram that may aid you in chasing down that gremlin. 

Tractor 1991-97 520-H Wiring DM Color (1).pdf 2.45 MB · 1 download

 

 

Will check this wire for sure. I think its going to be good as i check the wires down there already. maybe ill clean it and dielectric grease it.

 

Im going to guess, because it dies when i hit a bump, its a loose connection somewhere that provides power to the entire tractor. 

 

Leaning heavy towards the fuse block. Nothing is melted from what i can see on top. When i remove it ill know more.

 

If i did get a new fuse block, i will do the upgrade one i found. Has 3 seperate fuses and 12g wire already.

 

If im going to do it, im going to do it really good 1 time, and hopefully never mess with it again. 

[WHX?? 51,865]

21 minutes ago, stegs said:

will do the upgrade one i found.

You might have to share that. I have used just regular blade style fuse holders as pictured below. Changing out the original to original would be a real chore. Lots of wires stretched piano wire tight  under it. Below the fuse block is a cluster of plug in relays check that area as well. 

Edited February 10, 2022 by WHX??