Rear discharge 40”-42”deck on 520 H

[Gary S Minnesota 51]

I know this topic has been covered but I can’t seem to find the old threads.   As I recall there are two issues when mowing with Onan hydros.

I understand grass accumulation can occur quickly in the flywheel screen and then move to the rear cylinder cooling fins causing overheat problems on the rear cylinder.  I also read that the rear discharge unit tends to throw grass clipping at the Hydro fan unit possible causing over heating issues with the pump?  Also recall that some add a piece of vinyl baseboard molding to the RD deck to deflect the clippings away from the hydro unit?

I recently picked up a 1995 520H which came with the rear discharge deck.  I also have a an extra 48” side discharge deck that I use on my 314-8 tractor.  I think I will be mowing with the 520H unit this summer and am curious which style deck you guys recommend I use and why?

Thanks, Gary in Minnesota

[Blasterdad 2,691]

Both are okay, just blow of the tractor, deck, & engine after mowing, ( I use my leaf blower )

Most problems arise from neglect, owners never doing it. I have 520 H parts tractor that the PO killed by NEVER cleaning it, it was packed full of grass, dirt & crud. 

[kpinnc 11,941]

1 hour ago, Blasterdad said:

Both are okay, just blow of the tractor, deck, & engine after mowing, ( I use my leaf blower )

Most problems arise from neglect, owners never doing it. I have 520 H parts tractor that the PO killed by NEVER cleaning it, it was packed full of grass, dirt & crud. 

 

Absolutely correct. I use a leaf blower at minimum to clear clippings from everywhere I can reach. Bath works better, but you don't want to ever spray a hot engine. Leaf blower works in a pinch.

 

I also have an Eaton from a 520-H that had packed in clippings when I got it. It's now scrap metal as far as I'm concerned. 

 

But- to answer your question: I'd use the 48SD on the 520-H. The wider wheelbase makes getting up close to obstacles very difficult with a 42. Use the rear discharge on the 314-8. Not to mention the additional horses from the Onan make the 48 a better mower.

[Gary S Minnesota 51]

Thank you for the advice guys.  Yes, it make sense that the more powerful Onan will handle that 48” SD better than the 14 HP Koehler. I’ll probably mount the smaller RD deck on the 314-8 and use it occasional.  The RD also came with a mulching attachment made of a composite material that appears to just bolt on to the back of the deck.  May give that a try on my Fall Oak leaves!

I have a couple leaf blowers at the ready and I’ll be sure to blow everything clear on a regular basis.

Thanks Again!

[Ed Kennell 38,052]

Yes, the 48SD on the 520H makes sense.   Less grass in the hydro than the RD.    The twins will still suck grass in the engine screen.   I carry a long handled brush to keep mine clean while mowing with my 520H and 417H.    Make sure there are no oil leaks around the filter or the base plate the filter screws into.  A small seep here will make a sticky mess on the cooling fins and attract the grass.   Also make sure the grommet is around the filter sealing it to the tins.

 

The 42RD will be better on the 314-8.     The grass won't bother the gear drive as bad as the hydro.

 

 

[Gary S Minnesota 51]

Thanks Ed for the response.  The more I can learn about preventative measures the better.  There is a bit over a 1000 hrs on the Hobbs.  From what I was told the tractor was picked up by the WH dealer every Fall for scheduled maintenance.   Engine cooling fins appears nice and clean from what I can see, although I haven’t removed the tins. 

 

 

[Brockport Bill 1,660]

ditto the prior suggestions to switch the mowers - - in addition to previous suggestions,  clean underneath of the decks to avoid rot - - and common sense don't mow wet grass -- i use putty knife after every mowing to clean/scrape bottom of shell, plus power pressure wash every 3-4-5 mowings as needed - besides stopping shell rot the cleaner the bottom of shell the better quality cut and better discharge of clippings ---------- also if you have pulley/belt covers use leaf blower to blow out clippings from under the covers - - that will certainly cause rot thru on top of deck over time if not cleaned  - here is photo of the R.D. vinyl strip i attached of base wall/cabinate vinyl - use hex carriage bolts with rounded heads underneath to avoid catching clippings

[lynnmor 7,302]

Much of the grass that is collected on the Onan is tossed there by the left front tire.  Some time back a member showed fenders made from a plastic bucket to contain the debris.

[kpinnc 11,941]

High lift blades may help with the debris collected on the Onan flywheel screen. 

 

I say "may" because even the WH 60SD blows a little out the front. But my modded Exmark 48sd on my 520-H blows zero clippings out under the tire, but that is a high vacuum deck. The discharge side is a blaster...

 

[Gary S Minnesota 51]

Great stuff to know about!

 

Thanks everyone for sharing.  I think I’m going to spend the time to remove the tins and check for accumulated debris.  Then I’ll know for sure where I’m at from the start.  I did this on my 516H twice.  Required ALL my patience!!

[Ed Kennell 38,052]

4 minutes ago, Gary S Minnesota said:

I think I’m going to spend the time to remove the tins and check for accumulated debris.

Excellent,   perfect time to check for any seepage under the oil filter base plate.  It is held on by two small bolts and sealed to the block with a gasket that has a history of leaking.

[Lee1977 6,652]

On 3/2/2023 at 12:23 PM, Ed Kennell said:

Excellent,   perfect time to check for any seepage under the oil filter base plate.  It is held on by two small bolts and sealed to the block with a gasket that has a history of leaking.

Also when changing oil on the  520 Onan make sure to clean any oil in that half circle cup under the filter.

[peter lena 8,590]

@kpinnc  staring right at you , hiding in plane sight , would say that paint stage is perfect for an aerosol lubrication soak / rub down . if you were to blow that off , and spray on , let it sit a day, then clean soft cloth , and rub it down till dry , do it again . if paint is warm that helps transition, paint usually starts to show it self  . I  use a 6 " palm buffer at that stage with a cleaner wax to bring it out. done that on my 3 horses , so I  know it works . just an opportunity , pete