Jump to content
TC10284

520H shuts off and 60" deck issues

Recommended Posts

TC10284

I have a Toro Wheel Horse 520H with model # 73502 with a 60" deck. When I got the tractor Fall last year, I changed the oil, replaced the plugs with plugs that are supposed to go in it according to the manual, changed the oil filter, cleaned the air filter, and other general maintenance. Although I don't think the carb has been cleaned. 

My issues are these: 

  • Sometimes when I throttle up (mower deck not engaged), the tractor shuts off as if it just lost fuel. It's a quick shut off, no sputtering. Just dies.
  • Sometimes when I throttle down, the tractor shuts off as if it just lost fuel. It's a quick shut off, no sputtering. Just dies.
    • In both of the above cases, I can still see fuel in the fuel filter. 
    • I have not yet tested the fuel pump.
    • I am running fresh gas
  • At lower RPM (I'd estimate with the throttle at 20-40%), the engine shakes the whole tractor, until you open the throttle all the way, or throttle down all the way and the engine "settles" 
  • When the throttle is all the way in the lowest position, I often see the oil pressure light flashing until I throttle up.
    • It definitely has plenty of oil according to the stick.
  • My other issue is that when I engage the 60" deck, it drops the engine RPM from what I estimate from 100% to maybe 50 or 60%? Really seems like it almost is too much for the engine. 
    • The spindle bearings don't seem to be bad and rotate smooth. 
    • They have been greased with a new belt.  
Edited by TC10284

Share this post


Link to post
Share on other sites
 
Ed Kennell

It sounds like you may have several problems.  The sudden shut downs and oil light flashing could be an electrical issue.  The 520s are notorious for wiring problems.  Clean and tighten all connections including grounds and the 9 pin Molex  and fuse holders.   The stuttering and loss of power causes me to wonder if it is running on one cylinder.  Check the plug wires, and a new plug is not always a good one.   When it is stuttering, pull off a plug wire to see if it affects the performance. If it is running on one cyl, you may be able to determine which one is not firing.

Not saying the carb is OK, but typically a dirty carb causes the engine to surge and search for RPM.    Other Onan experts should be here soon to offer ideas.  Good luck.

  • Like 1
  • Excellent 1

Share this post


Link to post
Share on other sites
 
WVHillbilly520H

What oil type and filter did you use, NAPA or OE Cummins/Onan filter for best results as well as a good 10w30 or straight 30w motor oil for your oil pressure issues, but with the "miss" and die out you may have one cylinder dead (broken rod valve seat issues ect) from pulling that 60" deck which is hard on them how many hours showing on the clock, Jeff.

Share this post


Link to post
Share on other sites
 
953 nut
7 hours ago, TC10284 said:

I am running fresh gas

Have you been running gas with ethanol in it? Over time the ethanol will attack rubber parts and leave deposits in the fuel system that cause poor performance. Adding some Seafoam gas treatment to the fuel can be helpful.

http://www.buyrealgas.com/

https://www.pure-gas.org/

Share this post


Link to post
Share on other sites
 
TC10284
10 hours ago, Ed Kennell said:

It sounds like you may have several problems.  The sudden shut downs and oil light flashing could be an electrical issue.  The 520s are notorious for wiring problems.  Clean and tighten all connections including grounds and the 9 pin Molex  and fuse holders.   The stuttering and loss of power causes me to wonder if it is running on one cylinder.  Check the plug wires, and a new plug is not always a good one.   When it is stuttering, pull off a plug wire to see if it affects the performance. If it is running on one cyl, you may be able to determine which one is not firing.

Not saying the carb is OK, but typically a dirty carb causes the engine to surge and search for RPM.    Other Onan experts should be here soon to offer ideas.  Good luck.

Yeah, that's part of my concern as well. I can tell the wiring has been messed with. There are wiring nuts on some of the wires under the hood and under the rear fender/seat. 

I also have had the same concern about it running on one cylinder, so when I get off work, I'll check on that using your steps and let you know. It's not so much a stutter, but shuddering the whole tractor. I do know I tightened down the motor bolts when I serviced it. 

 

This tractor doesn't surge. I have an older model 520H that was surging when I tried to mow with it a couple weeks ago. That issue seemed to disappear on that one (so far). 

Edited by TC10284

Share this post


Link to post
Share on other sites
 
TC10284
5 hours ago, WVHillbilly520H said:

What oil type and filter did you use, NAPA or OE Cummins/Onan filter for best results as well as a good 10w30 or straight 30w motor oil for your oil pressure issues, but with the "miss" and die out you may have one cylinder dead (broken rod valve seat issues ect) from pulling that 60" deck which is hard on them how many hours showing on the clock, Jeff.

I used some new 30W motor oil from Advanced Auto. The oil filter, I can't remember the part number, but it is one recommended by the manual and comparing the filter number to one in a Stens parts book. 

 

765Hr on it, and I haven't put 1hr on it due to the issues. I've considered taking the 60" deck off it and putting the original 48" back on it, but I bought it to put the 60" deck on it (the newer model with the swept forward axles). I really thought it would've been able to handle it better than that, but I do suspect some engine issue(s). 

Share this post


Link to post
Share on other sites
 
TC10284
3 hours ago, 953 nut said:

Have you been running gas with ethanol in it? Over time the ethanol will attack rubber parts and leave deposits in the fuel system that cause poor performance. Adding some Seafoam gas treatment to the fuel can be helpful.

http://www.buyrealgas.com/

https://www.pure-gas.org/

I run 93 in everything I own. I try to get 93 pure gas as often as possible, but honestly that's a longer drive to the gas stations at the lake near where I live. So sometimes I do use 93 with "up to 10% ethanol". But I'm definitely aware of the junk that is caused by ethanol gas. I'll start using more gas treatment as I have some Stabil and Briggs on hand. 

 

Also, thank you for your service sir. 

Edited by TC10284
  • Like 1

Share this post


Link to post
Share on other sites
 
Ed Kennell

The 60" deck is not the problem.  A proper running P220 Onan will turn the 60" deck easily, or burn up a belt trying if the center spindle is locked up.

Again, I suspect it is running on one cylinder.  Hopefully it is an electrical problem and not the notorious  rear cylinder valve seat failure. 

  • Like 2

Share this post


Link to post
Share on other sites
 
lynnmor
32 minutes ago, Ed Kennell said:

The 60" deck is not the problem.  A proper running P220 Onan will turn the 60" deck easily, or burn up a belt trying if the center spindle is locked up.

Again, I suspect it is running on one cylinder.  Hopefully it is an electrical problem and not the notorious  rear cylinder valve seat failure. 

I agree with this.  Always, always check the compression first thing.  If you have a valve seat issue, that should show it.  Attempting to run a bad engine will only make it worse.  You can't tune out internal engine problems.

 

Now, knowing that the engine is sound, I would suspect that the carb needs cleaned.  If it were mine, I would pull the exhaust, intake and carb.  Inspect the intake for leaks at the seam, and rebuild the carb.  While apart, the valves should be adjusted and the exhaust painted because that is normal maintenance anyway.

  • Like 1

Share this post


Link to post
Share on other sites
 
TC10284
6 minutes ago, lynnmor said:

I agree with this.  Always, always check the compression first thing.  If you have a valve seat issue, that should show it.  Attempting to run a bad engine will only make it worse.  You can't tune out internal engine problems.

 

Now, knowing that the engine is sound, I would suspect that the carb needs cleaned.  If it were mine, I would pull the exhaust, intake and carb.  Inspect the intake for leaks at the seam, and rebuild the carb.  While apart, the valves should be adjusted and the exhaust painted because that is normal maintenance anyway.

OK, thanks for the info. Do you guys have some standard steps to test for the rear cylinder valve seat issue? 

Share this post


Link to post
Share on other sites
 
WVHillbilly520H
6 hours ago, TC10284 said:

I used some new 30W motor oil from Advanced Auto. The oil filter, I can't remember the part number, but it is one recommended by the manual and comparing the filter number to one in a Stens parts book. 

 

765Hr on it, and I haven't put 1hr on it due to the issues. I've considered taking the 60" deck off it and putting the original 48" back on it, but I bought it to put the 60" deck on it (the newer model with the swept forward axles). I really thought it would've been able to handle it better than that, but I do suspect some engine issue(s). 

I didn't say it wouldn't turn or handle a 60" deck, but if it had been using that deck since new and had a lots (1000+ of unknown maintaince) hours it does take its toll on the engine and frame, I've owned my anniversary 520H since new 760 hrs now but only used a 48" deck and tall wet grass will pull the engine down, I'm a firm believer in the Onan, like others have said check electrics first then check the carb, one way to check for vacuum leaks around the carb/intake is while the engine is running spray carb cleaner at the carb base and along the length of the intake if the rpms speed up you have a vacuum leak, other tips have been posted above.

Share this post


Link to post
Share on other sites
 
TC10284

So I did a little testing today after work. It took forever to get it started, BTW.

First, I took the fuel hose off the carb to see if the fuel pump was pumping. It was, although it wasn't a steady stream. I guess because I was only turning it over and the engine wasn't running. Then I put all that back together. 

I was finally able to get it to start. I pulled off the front plug wire. As soon as I did it died. Reconnected front plug wire. Started it back up. Disconnected rear plug wire. This time it ran for about 30sec and then died. Repeated that process. The second time it basically sounded/ran the same. I even throttled it up and it ran the same as if the plug wire was connected. 

 

Attached are some pictures I took of the wiring. Note that I did NOT do any of that. If it were me, and it were possible, I would have soldered them back together and used heatshrink tubing.

See if you notice any issues here:

https://imgur.com/a/5f7yS

Edited by TC10284

Share this post


Link to post
Share on other sites
 
cleat

Rear cyl is dead.

 

Next step would be a compression test.

 

You might get lucky and it will be a bad plug, wire, or coil but I doubt it.

 

Cleat

Share this post


Link to post
Share on other sites
 
Ed Kennell

                                                                                                :text-yeahthat:                                                                                                                                                              

 

 

The fact that it would not run on either single cylinder indicates both cylinders may have low compression or something common to both cylinders (the coil) is weak.

All my twins (Brigs, Onan ,Kohler) will run on either cylinder.

Edited by Ed Kennell
  • Excellent 1

Share this post


Link to post
Share on other sites
 
TC10284
41 minutes ago, Ed Kennell said:

                                                                                                :text-yeahthat:                                                                                                                                                              

 

 

The fact that it would not run on either single cylinder indicates both cylinders may have low compression or something common to both cylinders (the coil) is weak.

All my twins (Brigs, Onan ,Kohler) will run on either cylinder.


It did run the second time with the rear plug wire disconnected. Acted like nothing changed actually. 

 

 

Share this post


Link to post
Share on other sites
 
TC10284
1 hour ago, cleat said:

Rear cyl is dead.

 

Next step would be a compression test.

 

You might get lucky and it will be a bad plug, wire, or coil but I doubt it.

 

Cleat

 

I'll do a compression test as soon as possible, along with checking the plug, wire, and coil. 

 

What would you guys suggest about the wires connected with wire nuts? Mostly that one that has four wires in one wire nut - two reds, two whites. Is that not an issue? 

Share this post


Link to post
Share on other sites
 
Ed Kennell
16 minutes ago, TC10284 said:


It did run the second time with the rear plug wire disconnected. Acted like nothing changed actually. 

 

 

OK, sorry, my bad. I thought the second test was a repeat of the first.     So the rear is dead.    

Share this post


Link to post
Share on other sites
 
cleat
6 hours ago, TC10284 said:

 

I'll do a compression test as soon as possible, along with checking the plug, wire, and coil. 

 

What would you guys suggest about the wires connected with wire nuts? Mostly that one that has four wires in one wire nut - two reds, two whites. Is that not an issue? 

Here is the wiring diagram.

Later model 520 wire diagram.pdf

 

It looks like they removed the PTO safety switches and also the seat switch.

 

If you follow the wiring diagram and see which wires are supposed to connect then you can determine if yours is now wired properly.

 

You do not have many if any safety switches currently functional.

 

Cleat

Share this post


Link to post
Share on other sites
 
Steve_O
6 hours ago, TC10284 said:

 Mostly that one that has four wires in one wire nut - two reds, two whites. Is that not an issue? 

 this is where the fuse block used to be (part# 67-7160).  I'd replace the fuse block.

  • Excellent 1

Share this post


Link to post
Share on other sites
 
WVHillbilly520H
11 hours ago, TC10284 said:

So I did a little testing today after work. It took forever to get it started, BTW.

First, I took the fuel hose off the carb to see if the fuel pump was pumping. It was, although it wasn't a steady stream. I guess because I was only turning it over and the engine wasn't running. 

 

Attached are some pictures I took of the wiring. Note that I did NOT do any of that. If it were me, and it were possible, I would have soldered them back together and used heatshrink tubing.

See if you notice any issues here:

https://imgur.com/a/5f7yS

OK first on the fuel pump it's a "pulse" style pump there for it only "squirts" fuel on a vacuum pulse faster as the rpms pick up, second the wire nutted wiring is where the fuse panel used to be (not good) also looks like the main charging wire is burnt and corroded (the 12-14 ga wire running by the battery) you need to download the demystification guide from here for your model (IE 73501/2) 520H for the wiring diagrams and trouble shooting also the Onan engine service manual will help too, I suggest going through and checking ALL  the wiring/connections for corrosion/breaks ect especially the 9 pin plastic connector between engine and the rest of the dash wiring, here's a few pics of how it could/should look after cleaning up the harness, BTW looks like it could use a good thorough cleaning front to back, take the rear fender pan off I suspect major dirt/grease build up on the hydro pump/fins, as well as good time to change out the fuel lines and maybe the fuel shut off on the tank, Jeff.

IMAG2020.jpg

IMAG2081.jpg

IMAG3089.jpg

IMAG3395.jpg

IMAG2134.jpg

  • Excellent 1

Share this post


Link to post
Share on other sites
 
TC10284

To all that replied: 

So it looks like I not only have an engine problem, but a wiring problem to resolve. The person I bought it from said "it ran fine" (it had a 48" deck) just "shook sometimes". 

 

OK, I will order a new fuse box (67-7160) and see if I can get that rebuilt. It might be a challenge for me, so I may have to come back for advice. 

 

As far as the safety switches, the only ones I'm concerned about I guess would be the PTO safety - just in case for whatever reason if I fell out of the seat while mowing, even though I don't have anywhere near rough terrain at my house. I get the point of it though. 

 

Also an oil level safety or temp safety switch, if that's even a feature in the first place. Can you tell if those have been removed or what to look for, if applicable? 

 

I'll also check all the wiring and connections for corrosion, etc. 

 

 

Edited by TC10284

Share this post


Link to post
Share on other sites
 
TC10284
5 hours ago, WVHillbilly520H said:

also looks like the main charging wire is burnt and corroded (the 12-14 ga wire running by the battery) 

 

 

 

I'm not seeing what you're seeing. Sorry. 

I'll go look closer after work. 

Share this post


Link to post
Share on other sites
 
WVHillbilly520H
9 minutes ago, TC10284 said:

I'm not seeing what you're seeing. Sorry. 

I'll go look closer after work. 

This first pic white and red wires...and as far as I can tell your engine temp sensor is still hooked up second pic of yours...there's also a hydro(trans temp sensor as well) and again your pic look at the build up (grass/oil) under the fuel tank I just used a pic of mine as reference and it just had 236 hrs on it when it got it little to no maintaince, Jeff

Screenshot_20180403-115954.png

Screenshot_20180403-115924.png

Screenshot_20180403-120329.png

  • Like 1

Share this post


Link to post
Share on other sites
 
TC10284

Just an update:

I took a quick look at the rear plug this afternoon and it had crud built-up completely in the gap. This is supposed to be a new plug (when it was installed late last year and little use of the tractor). I cleaned it off, put it back in. Didn't run any better. Forgot to check for spark after I cleaned it because I was kind of in a rush. I'll look again tomorrow. I also got a plug tester and compression checker from my dad to test those two things. 

Edited by TC10284
  • Like 1

Share this post


Link to post
Share on other sites
 
TC10284

Update:

Spark plug test - Good. Both firing. Can see spark. 

Compression test - Bad. Rear cyl has 0psi. Front cyl has ~30psi.

 

Guess I know what the problem is. 

 

So my next question is, is it better to rebuild or get another engine? 

If rebuild, what all is involved? 

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...