520H bogging down and stalling engine

[Ed Kennell 37,961]

11 minutes ago, Blasterdad said:

Me too....

X3

 

[nylyon-(Admin) 7,229]

Just fixed it, try now guys

[nylyon-(Admin) 7,229]

Wow Rob, that was certainly some carnage, wonder what would cause the rod to shatter like that?  Sounds great now though and you have one of the awesome 520’s!

[kpinnc 11,842]

4 hours ago, Rob R said:

As promised here she is running PROUD!

 

Sounds great!

 

There are plenty of mods to keep that rear cylinder cool. I would say with a P220, looking into them is a good idea before mowing season. 

 

Some folks put a vent in the belt guard. I cut mine out altogether. I also put a "peep hole" over the rear cylinder that let me ensure no grass clippings clogged the cooling fins. Probably a bit of overkill, but that is normal for me.

 

Regardless, I'm glad it all worked out. You saved another Wheel Horse! 

 

 

[Lee1977 6,632]

I just cut the belt guard off on my 520 -H isn't need on a hydro. I'm old enough to keep my fingers out of it.

[Rob R 966]

HI Fellow wheelers thought I would do an update on the 520H. I have conquered all the common electric issues mostly by ripping out the light plastic fuse box and replacing it with protected heavy duty in line fuse holders so now all the gages work, and it charges like a champ. The engine starts beautifully and runs great, the deck is refurbished and also cuts well. I vented the belt guard, so it is cooling the back cylinder. 

 

So the only remaining issue is that when it gets really hot and I am putting the "onions" to it i.e. going up a steep hill it will puff some smoke (not white). I did a compression check on both cylinders yesterday and was surprised with the results 120 on the front and 122 on the back (cylinder I replaced the connecting rod on) so compression and rings should not be a problem same with head gasket(s).  So I am wondering if the valve seals are shot and causing the issue???  Are these relatively easy to replace, what disassembly and special tools are required. Do you have any other ideas..... Thanks men  p.s. i cut slots in the belt guard to help with back cylinder ventilation and it works well. 

Edited May 31 by Rob R

[lynnmor 7,294]

Only the intake valves have seals.  You likely are due for a valve adjustment anyway so getting to the seals is just some more work.  You will need to remove the exhaust, intake and valve covers for adjustment.  To get to the seals the valve springs need to be compressed and removed.  Depending on the type of valve spring compressor used the heads may need to come off.

[Bill D 1,891]

Any chance it's running rich?  White smoke would be oil burning, black smoke sounds like it's running rich.  How do the plugs look?

[Rob R 966]

22 hours ago, Bill D said:

Any chance it's running rich   White smoke would be oil burning, black smoke sounds like it's running rich.  How do the plugs look?

It might well be running a bit rich Bill, but my understanding is the carb in NON-adjustable. I have not monkied with since it starts real easy, runs smoothly and idles nicely so.... really didn't want to mess with it unless I know what to do.

I did pull the plugs to do the compression chk they did have some carbon on the rims, again I was truly shocked with the value(s) 120 PSI and 122 PSI respectfully, so I cleaned them and screwed them back-in. 

[953 nut 54,946]

8 minutes ago, Rob R said:

. I have not monkied with since it starts real easy, runs smoothly and idles nicely 

If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up.

[Bill D 1,891]

3 hours ago, 953 nut said:

If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up.

On the Onan "P" series the condenser is connected to the positive terminal.  This controls voltage spikes that could damage the ignition module or cause misfires.

[953 nut 54,946]

7 hours ago, Bill D said:

On the Onan "P" series the condenser is connected to the positive terminal.  This controls voltage spikes that could damage the ignition module or cause misfires.

Does that mean it couldn't possibly be the problem and should be totally ruled out?

Edited June 2 by 953 nut
fat finger

[Rob R 966]

12 hours ago, 953 nut said:

If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up.

The engine runs well no missing, popping or backfires the issue is that when under heavy load (mowing with a 48" mower and going up a steep incline she blows a considerable amount of smoke all the while running just fine. 

[953 nut 54,946]

3 minutes ago, Rob R said:

The engine runs well no missing, popping or backfires the issue is that when under heavy load (mowing with a 48" mower and going up a steep incline she blows a considerable amount of smoke all the while running just fine. 

So it isn't BOGGING DOWN and STALLING as in the thread's title?

[lynnmor 7,294]

1 hour ago, Rob R said:

The engine runs well no missing, popping or backfires the issue is that when under heavy load (mowing with a 48" mower and going up a steep incline she blows a considerable amount of smoke all the while running just fine. 

Are you using exactly 2 quarts of SAE 30 oil and the correct oil filter?  I use Fleetguard PF3339 or Onan 122-0800 filters and Kohler HD30 oil.  Is the air filter new with a clean pre-filter?  It the breather clean and assembled correctly?

[Rob R 966]

8 hours ago, 953 nut said:

So it isn't BOGGING DOWN and STALLING as in the thread's title?

Correct that was the original problem which was the broken connecting Rod it ran surprisingly well stumped me completely at the beginning but I found it quickly as it had no power.  Page 1 has all that detail and a video of the engine running with the new conn rod. 

Edited June 2 by Rob R

[Rob R 966]

7 hours ago, lynnmor said:

Are you using exactly 2 quarts of SAE 30 oil and the correct oil filter?  I use Fleetguard PF3339 or Onan 122-0800 filters and Kohler HD30 oil.  Is the air filter new with a clean pre-filter?  It the breather clean and assembled correctly?

Yes excepting the engine oil I used a multi-grade oil it is due for a change so I can definitely go to the Sae 30 weight to be honest was thinking about going to a 40 weight

[lynnmor 7,294]

7 minutes ago, Rob R said:

Yes excepting the engine oil I used a multi-grade oil it is due for a change so I can definitely go to the Sae 30 weight to be honest was thinking about going to a 40 weight

I wouldn't do 40 unless the engine is spent.  !0w-30 is OK for cold temperatures or light usage.

[Rob R 966]

8 minutes ago, lynnmor said:

I wouldn't do 40 unless the engine is spent.  !0w-30 is OK for cold temperatures or light usage.

Okay the thing that has me stumped is that since the conn rod change it runs great and I have 120PSI on the cylinder one and 122PSI on the cylinder two with the new rod....so engine is definitely not spent, that's why I was thinking the oil is getting into the cylinders perhaps thru the valve seals..... but then I thought again when I start it little of no smoke so kinda crossed that one off...... 

[lynnmor 7,294]

You could have good compression with worn oil rings.  I have an Onan torn down right now that had good compression and found one oil ring with about 3/8” missing from the end, no clue where it got to.  I tore it down because of rod noise and there was excessive clearance in the crank end.  When we buy used engines it is impossible to know the extent of the abuse, many don’t take care of oil changes or air filters.  These engines get dusted easily since they work in harsh environment.