520H air cleaner

[formariz 11,987]

It seems to be that all the air available to the carburetor on the 520H cones through the short 2" hose that is inside of engine tin. That however brings in all kinds of dirt sucked through the air intake, clogging the pre filter foam real quickly.

Has anyone tried introducing a foam pre filter into the tube or something similar?That would probably also clog even faster due to the small surface area? Perhaps moving that intake or extending it elsewhere?

Has anyone been bothered with this? Curious as to everyone's opinions.

[1995 520H+96+97 937]

@formariz Easy fix.

[WVHillbilly520H 10,373]

Cass, like I've said before I've owned my anniversary model since new if the prefilter is "clogging" too fast then 1) it's doing its job during dusting conditions (and that ONAN pulls some air) and 2) maybe you have a bit too much oil it I usually only add a teaspoon or so oil and "wring" it through thoroughly but when I first changed my out years ago I got too much oil on it and it seemed like it was attracting every ounce of dirt dust and chaffe in the area. Hope this helps.

[formariz 11,987]

I pretty much do the same as you with the oil. Although I don't have dusty conditions when I mow this year without as much rain there was much more dry grass debris stuck to it. I am just trying to see if there is a way to improve it (I know always trying to reinvent the wheel).

 

I guess also my main question is if the two inch inlet is enough without having the additional help of the flywheel forcing air into it. Will it on its own provide enough air for that engine? I see that @1995 520H+96+97 uses it that way. Any difference in power?

Edited October 11, 2019 by formariz

[Blue Delta 35]

1 minute ago, formariz said:

I guess also my main question is if the two inch inlet is enough without having the additional help of the flywheel forcing air into it. Will it on its own provide enough air for that engine?

 

The intent is to move air that has less dust/dirt particles into the air box by the use of centrifugal force, the forced air should be cleaner then if it was just breathing not under forced conditions. Also the forced air will clean the air box (to some degree).

[formariz 11,987]

4 hours ago, Blue Delta said:

 

The intent is to move air that has less dust/dirt particles into the air box by the use of centrifugal force, the forced air should be cleaner then if it was just breathing not under forced conditions. Also the forced air will clean the air box (to some degree).

I understand its intent, however it looks like it is not working as intended since that flywheel sucks in all kinds of debris to the point that I am occasionally clearing the screen of grass and leaves which is a typical problem with the Onans. Also if there is not an  outlet in the air box for any excess air not sucked by carburetor,  box can not be cleaned by the forced air, therefor the constant clogging of pre filter. I am just thinking that a passive air feeding system would not clog filter as much.

Edited October 11, 2019 by formariz

[tom2p 2,394]

14 hours ago, formariz said:

It seems to be that all the air available to the carburetor on the 520H cones through the short 2" hose that is inside of engine tin. That however brings in all kinds of dirt sucked through the air intake, clogging the pre filter foam real quickly.

Has anyone tried introducing a foam pre filter into the tube or something similar?That would probably also clog even faster due to the small surface area? Perhaps moving that intake or extending it elsewhere?

Has anyone been bothered with this? Curious as to everyone's opinions.

 

yes - agree it can be annoying ; cutting grass with an Onan powered Wheel Horse can be annoying as stuff will fly everywhere 

 

I keep extra supply of the foam pre-filters on hand and change more often 

 

don't be tempted to not pre-treat or use less oil (or whatever) on the pre-filter just to prevent more dirt and foreign substances from being attracted to the pre-filter - that would be counter productive ; the job of the pre-filter is to trap that stuff and keep it out of the filter (and engine)

[tom2p 2,394]

I typically use a foam filter oil on the Wheel Horse foam pre-filters 

 

stuff is sticky and works very well 

 

(like below) 

 

 

[Blue Delta 35]

There is no doubt an issue in severe conditions, I think the difference in size between the upper and lower air box tins is the outlet, although I see some rubbing on my 16 in one place.

 

If I had to correct it personally I would remove the current air box completely and use a Donaldson style setup inner and outer (see walkers for example) with an adaptor flange from the carb, but without mangling a bonnet there isn’t much space on top of the engine to fit it (other issue is that it may make the engine run rich and require rejetting, I know Toro engines with the canister filters need a different carb fitted)

[formariz 11,987]

1 hour ago, Blue Delta said:

If I had to correct it personally I would remove the current air box completely and use a Donaldson style setup inner and outer (see walkers for example) with an adaptor flange from the carb, but without mangling a bonnet there isn’t much space on top of the engine to fit it (other issue is that it may make the engine run rich and require rejetting, I know Toro engines with the canister filters need a different carb fitted)

I been actually thinking of going with that kind of idea.

Would it run rich due to the fact that it would not have air literally forced into carburetor therefor having less air in mixture?

[Blue Delta 35]

1 minute ago, formariz said:

Would it run rich due to the fact that it would not have air literally forced into carburetor therefor having less air in mixture?

 

I am thinking of extra length might give more of a restriction, the Kohler’s seem to run alright regardless of filter box/intake type. If you where going to do it definitely have a build post and document it - and a spare bonnet. It will be obvious by the plugs if the mixture has changed, if it becomes rich I wouldn’t mind it as much as long it wasn’t bogging down/fouling but lean would be bad, especially for the rear cylinder.

[JoeM 7,871]

Is there enough room under the hood to double stack the filters? I have one machine that has a "shaker hood" and I stack an old dodge filter on the top of the factory filter. This push's the chrome plated cover up through the hood, that is thicker than a standard Onan filter.

I just added a piece of all thread and a nut coupler I picked up at Lowes.

I will look at my 520 tomorrow. (the hood says 516 because I needed to have a hood without lovers) tractor is 520.

I think this is a pic with the two factory filters stacked,

Pic with old Dodge filter on top of the factory filter.

 

[lynnmor 7,302]

The 520HC had a taller filter element, I don’t know what it might take to make that work.

[WVHillbilly520H 10,373]

@formariz, that chrome top should not completely "seal" against the black base as the flywheel fan is "forcing" air into the "air box" what isn't being used should be expelled through the "venting" of top and bottom sections of the air box... Basically what @Blue Delta was describing in post #5 ... Also the engine will only use as much air as "atmosphere" will allow with "boosting" it mechanically (turbo or other means of forced induction)... The only other advice I can give is think of the old style oil bath air filters of course the bigger particles are suspended in the oil and you can see them better vs the paper media of modern filters again IMHO and from personal experiences the foam pre filter is doing its job the way it was designed.

[formariz 11,987]

1 hour ago, WVHillbilly520H said:

@formariz, that chrome top should not completely "seal" against the black base as the flywheel fan is "forcing" air into the "air box" what isn't being used should be expelled through the "venting" of top and bottom sections of the air box... Basically what @Blue Delta was describing in post #5 ... Also the engine will only use as much air as "atmosphere" will allow with "boosting" it mechanically (turbo or other means of forced induction)... The only other advice I can give is think of the old style oil bath air filters of course the bigger particles are suspended in the oil and you can see them better vs the paper media of modern filters again IMHO and from personal experiences the foam pre filter is doing its job the way it was designed.

Makes sense that some air will probably escape through the joint between lids. I also agree that the pre filter is definitely doing its job. No doubt about that. I just think that it is unnecessary and counter productive to have all of that debris being forced into it. Gets to the point that it needs to be cleaned and re oiled every four or five mowing s.

[JoeM 7,871]

I figure that tube is on there for the engine to draw warmer air in cooler weather and prevent carburetor icing. I have seen on some Kohler twins were you can rotate the air cleaner from summer,  (open to atmosphere), to winter setting that draws air from the tins. Same as those old Chevy V8's with those heat risers on the air cleaner. Unnecessary in warmer weather.

Highly unlikely it would ever work for boost or cleaner centrifugal air. I think that clean air thing was a pipe dream. With as much dirt those fly wheels suck up.....not a shot. 1995 got the right idea sealing that hole. Looking at the most modern engines, that design has all but gone away.

Edited October 12, 2019 by OILUJ52

[troutbum70 857]

According to wheel horse/kohler rep of many years ago that was only beneficial if tractor sat out in cold weather, helped bring engine up to operating temperature much quicker. Mine always sits inside and warm so have always left air cleaner in summer position.

[tom2p 2,394]

possibly just a poor design 

 

maybe a good way to sell a lot of air filters 

 

and the warm air thing makes little sense - because most grass cutting is done in warmer weather 

 

 

the shroud filling up with debris is also annoying 

 

I considered a fender or shroud of some type for the left front - after watching the fan pull in debris and leaves from the left front tire as the tractor moves forward 

 

at one point I mounted a small flat snow brush with Velcro on the left cover - so I could brush off the debris from the shroud without dismounting 

 

 

Edited October 12, 2019 by tom2p

[tom2p 2,394]

On 10/11/2019 at 12:46 AM, 1995 520H+96+97 said:

@formariz Easy fix.

 

simple - and might be the best solution !

[WVHillbilly520H 10,373]

I know it's not a WH but the Mahindra eMax I have with the water cooled diesel the cooling fan sucks the cut grass and chaffe up on the radiator screen (from the left front tire kicking it up) till it goes into "limp" mode then I have to let it idle down go to the garage and blow the screen off and start all over is it a poor design or just nature of the beast... we don't live in a perfect world the engineers can't possibly foresee every little problem that arises could it be better possibly or do we collectively over analyze certain things... From my perspective (only) I bought my equipment to use if it gets dirty from use so be it and if I'm noticing dirt getting into hidden places then I'm doing preventative maintenance and no further problems should arise ,most if anything these are small annoyances ... for 20+ years I have used my 520s in dirty dusty conditions mowing grass gardening and dirt/gravel driveway repair... and knock on wood no mechanical engine problems like valve seat issues ect and neither the Anniversary 520H or my eMax will ever been shiny untainted new again and I'm ok with it.

[Darb1964 1,042]

I just keep extra pre cleaners on hand, chang as needed. My 1989 520-h has 2000 hours on it with out engine trouble, I think you fellas might be over thinking things. Keep it clean, when conditions are dusty change the oil more and the pre filter more often. 

[formariz 11,987]

27 minutes ago, Darb1964 said:

I just keep extra pre cleaners on hand, chang as needed. My 1989 520-h has 2000 hours on it with out engine trouble, I think you fellas might be over thinking things. Keep it clean, when conditions are dusty change the oil more and the pre filter more often. 

I am certainly trying to somewhat reinvent the wheel here. However that is all part of the fun and of the learning experience in trying to improve something so it performs better or requires less maintenance. It’s all part of the hobby and of the sharing of ideas and experiences. It is always interesting to see what others think and what  other approaches they have on it. 

[lynnmor 7,302]

The Onan engines were designed primarily for generators and later sold to lawn and garden equipment manufacturers.  A generator is usually operated in a better environment without the grass clippings and extreme dust that tractors must endure.  If you keep this in mind, then you know the importance of keeping the air filter and cooling fins clean and why they are less tolerant of dirt. 

[JoeM 7,871]

There was just about a 1/16" clearance under the hood with two air cleaners stacked. FYI

Not sure if the are all that close.

[Greentored 3,201]

Resurrecting the dead here, sorry. Brand new member here and my very first technical post yesterday was on this same exact subject, then stumbled on this thread this morning. Glad to know it can be blocked off- I want to push every bit of air across the fins as possible, maybe this will help a bit.

Joe M, killer job on that shaker, it looks factory, love it!!