Plastic belt cover on pto 520H

[Phatboy 565]

Can anyone tell me if by taking off the black plactic belt cover help with rear cylinder cooling on the 20 hp onan ? Or not i wanna know , cause if it helps im gonna take off if not im gonna leave it on,, i cant bring myself to drill holes in the red metal belt guard so i wanna do what i can to help cool rear cylinder if removing that definatly helps cooling rear cylinder off it comes !!

 

Edited March 22, 2016 by Phatboy

[N3PUY 1,031]

It's the belt guard that stops the air flow. 

Drill some nice holes.

[Ed Kennell 35,724]

Pick up another belt guard at the show and drill it.

 

 

 

 

Edited March 23, 2016 by Ed Kennell

[ericj 1,576]

i took the belt guard off my 99 315-8 a long time ago, partially becuase one year while plowing snow the handle messed up the threads on the stud on the belt guard. i believe it's down in the basement somewhere. As far as the drilling hole in your belt guard or buying another one and drilling it. how much yard do you mow is it over an hour of run time ? It takes me just under an hour so i'm not to concerned as much about the air flow over the back cylinder. if i had a couple of hours of run time to mow i would definitely do something to help cool the back cylinder. what i'm saying is the longer you run it the more you need to worry about keeping it cool. the shorter the run time not as much

 

 

 

 

 

eric j 

[Phatboy 565]

It only takes me about 40 minutes to cut my grass ,, but like i wanna do a plow day here and there and dont wanna worry about over heating the rear cylinder.. And having valve seat problems,, ugg the struggle is real !! Lol

[Ed Kennell 35,724]

I only use my 520 for snow blowing so grass clippings clogging cooling fins and rear cylinder  overheating is not a problem for me.

I am not aware of any  engine temperature / running time data, but with the drilled belt guard and the heat collection shroud that I have on my 520, the cab heats up and stays 35F above outside temperature very quickly.     This is with only the heat from the rear cylinder.

[cleat 4,947]

I would think an air cooled engine could overheat in way under an hour if worked hard in hot weather with inadequate cooling.

 

That said, I got all of my Onans well used with all the factory covers in place (mine did not ever have the plastic cover) and all run well so they lived for years that way with no ill effects. I have drilled the belt covers on all of them just for my peace of mind but may not really be required.

 

 

Likely more important to keep the inlet screen over the flywheel clean. That seems to be more of a problem with smaller decks. My 42" deck is terrible and I need to clear that screen very often, the 48" deck seldom clogs it and the 60" deck on a 520 does not seem to put any grass whatsoever on the screen.

 

 

Edited March 23, 2016 by cleat

[JAinVA 4,619]

Drilling holes in the belts guard definitely improves airflow, but if you want to maximize airflow remove the front portion of the belt guard brace & attachment ear. As you can see from the photographs, once these parts are removed how easily it is to see any stoppages in the cooling fins. Luck, JAinVA

 

JimAnderson

Gloucester, VA

[Phatboy 565]

17 minutes ago, JAinVA said:

Drilling holes in the belts guard definitely improves airflow, but if you want to maximize airflow remove the front portion of the belt guard brace & attachment ear. As you can see from the photographs, once these parts are removed how easily it is to see any stoppages in the cooling fins. Luck, JAinVA

 

JimAnderson

Gloucester, VA

I like the way you cut yours janiva now all i have to do is find someone to do that for me haha... I dont know what you mean by ears and front part of attachment tho ,, ya mean the black brace behind belt guard ? Im going oit to the garage now to see if i cam figure out what ya mean..

[wrightorchid 261]

Great mods.  Looks like they came that way from the factory!

[Bert 760]

1 hour ago, JAinVA said:

Drilling holes in the belts guard definitely improves airflow, but if you want to maximize airflow remove the front portion of the belt guard brace & attachment ear. As you can see from the photographs, once these parts are removed how easily it is to see any stoppages in the cooling fins. Luck, JAinVA

 

JimAnderson

Gloucester, VA

The guard brace is something worth removing in my opinion. It blocks a lot of air flow. I did a little more cutting on mine and have run a 60 inch deck for over four hours in the blistering southern heat without the engine showing any signs of being overly hot

Edited March 23, 2016 by Bert

[JAinVA 4,619]

Phatboy,

    In the second  photo the guard brace and guard ear are visible.The guard is held in place by the shiny nut and washer.In the first picture these parts are missing.The guard brace still has an elongated  slot where an angle clip can be installed to secure the upper part of the belt guard if needed.JAinVA

JimAnderson

Gloucester,Va

[Phatboy 565]

4 hours ago, JAinVA said:

Phatboy,

    In the second  photo the guard brace and guard ear are visible.The guard is held in place by the shiny nut and washer.In the first picture these parts are missing.The guard brace still has an elongated  slot where an angle clip can be installed to secure the upper part of the belt guard if needed.JAinVA

JimAnderson

Gloucester,Va

Aahhh i see what ya mean JAinVA,,, yea that black brace alone would create a bunch more air flow if removed ,,, heck if i at least do that that would definatly cut down on alot of heat all by itself ,, thanks for the pics buddy and explanation ,, it really helped alot !!!

[JAinVA 4,619]

Phatboy,

        Glad to help out.If you look closely at the picture Bert posted you will notice that the lower shroud actually routes the cooling air up wards.I believe that removing the brace front and belt guard ear do more to increase airflow than all the holes in the belt guard.I didn't realize this until I had milled the slots in the guard.Berts mod definitely gives max airflow.JAinVA

JimAnderson

Gloucester,Va

Edited March 24, 2016 by JAinVA

[ericj 1,576]

proper maintenance and keeping the air inlet screen clean will allow your motor to survive if running for under an hour, that's why so many have survived all of these years with out the belt guard modifications. but if you feel the need to give you onan more air by all means do so. i have some extra belt guard so i may try some different modification to some of mine, can't do much more then drill some hole, don't have access to a mill to cut slots or anything fancy, and i will use a belt guard off a non onan motor tractor to cut the to mount off and remove the brace and try it. thanks for all the info.

 

 

 

 

 

eric j    

[cleat 4,947]

9 hours ago, Bert said:

The guard brace is something worth removing in my opinion. It blocks a lot of air flow. I did a little more cutting on mine and have run a 60 inch deck for over four hours in the blistering southern heat without the engine showing any signs of being overly hot

 

Wow, nothing blocking the air here. Does the guard seem solid still at the top front ?

 

 

[JAinVA 4,619]

Bert,

   I don't mean to hi-jack the thread but does your 518 have the gear reduction steering? I see it has the swept forward axle but I thought 518s had straight front axles so I'm curious.JAinVA

[Bert 760]

18 hours ago, JAinVA said:

8 hours ago, cleat said:

 

Wow, nothing blocking the air here. Does the guard seem solid still at the top front ?

Yes very solid. I was wondering the same thing about JAinVA's mod? I'm thinking of using his idea on my 520

 

8 hours ago, JAinVA said:

Bert,

   I don't mean to hi-jack the thread but does your 518 have the gear reduction steering? I see it has the swept forward axle but I thought 518s had straight front axles so I'm curious.JAinVA

This is not a stock 518, it's got a 520 HC rear, lift, and front axle. I added gear reduction steering as well. It was while putting it all together that  I realized that brace had to go 

[Save Old Iron 1,563]

On 3/22/2016 at 6:52 PM, Phatboy said:

, i cant bring myself to drill holes in the red metal belt guard so i wanna do what i can to help cool rear cylinder if removing that [defiantly] helps cooling rear cylinder off it comes !!

 

at this point, no data has ever been presented to confirm any reduction in rear cylinder temperature by ventilating the belt cover. Evidence shows more effort has been made to perform the mod than investigate the benefit (if any) realized from the mod.

 

My sense is this mod falls squarely under the 500 series "tribal knowledge" category and best that can be said is (like chicken soup) "it couldn't hurt".

 

 

 

 

 

Edited March 27, 2016 by Save Old Iron

[Tankman 3,515]

I have never had the plastic PTO belt covers on my '90 520-8. 

 

The Onan performs well, summer or winter. Never over heated, I think.

 

I might note, the air intake screen is always kept clean. 

No holes or slots in the steel guard.

Edited March 28, 2016 by Tankman

[WVHillbilly520H 10,369]

755 hrs and still going strong on my bought new anniversary model no drill or cut outs, and I mow approximately 3 acres then run a sweeper afterwards sometimes turns into a 6 hr day...and keeping a watch on the flywheel screen while mowing,but the biggest thing to remember is after mowing use compressed air to blow out clippings/chaffe from the engine tin, air fins, and flywheel/blower housing and rear transaxle that helps cool things off afterwards,and maybe even garden hose wash/rinse off too...that's probably how mine has lasted as long here mowing 80+ degree days,Jeff.

[JAinVA 4,619]

On ‎3‎/‎27‎/‎2016 at 10:05 AM, Save Old Iron said:

 

at this point, no data has ever been presented to confirm any reduction in rear cylinder temperature by ventilating the belt cover. Evidence shows more effort has been made to perform the mod than investigate the benefit (if any) realized from the mod.

 

My sense is this mod falls squarely under the 500 series "tribal knowledge" category and best that can be said is (like chicken soup) "it couldn't hurt".

 

Some time ago I asked the question of the Onan owners here that have had intake valve issues if anyone had a problem with the front intake valve.I ask this question again.Memory says that most of the problems are with the rear seat in this service.If that is true then I think that is more than tribal knowledge.I am a firm believer that an air cooled engine needs air to stay alive.I also believe that drilling the belt guard has little effect  on air flow.The parts I have identified do more to block air flow than the belt guard.That is a fact and the pictures show it.I would rather spend a few hours to prevent a potential problem than spend time and money to fix a valve seat issue.I don' t need to put a pyrometer on the cylinders as I can tell more air is flowing than before the mod.   JAinVA

JimAnderson

Gloucester,Va

 

 

 

 

 

Edited April 5, 2016 by JAinVA

[WVHillbilly520H 10,369]

Haven't had valve issues yet with mine I bought in '98, can't  elaborate on any of that, but the 520H I bought Friday with 236 hrs on the clock looks like it has 20 + yrs of gunk packed everywhere on it but sounded very tight while driving it up on the truck,Jeff.

[JAinVA 4,619]

WVHillbilly,

       236 on the clock,nice!Sounds like a great score.Keep the cooling fins clean and the oil changed and you should have this machine for many years.Luck,JAinVA

[WVHillbilly520H 10,369]

JAinVA, I have had my anniversary 520H since new 18 yrs now & 755 hrs and hopefully this one many years too...also bought a 523Dxi 282 hrs (not running as of now) same day, place and original owner, from my original dealer in WV (check out N.O.S.522 xi found) more pics and info forth coming,Jeff.