Easiest way to keep rear cylinder and shroud clean

[Phatboy 565]

Ok guys what is they easiest way to keep rear cylinder on onan 20 clean and free from debree such as grass clippings ,, use air compressor from PTO side or from shroud side? Or water and sqirt in shroud while running ? Again sorry for all the noob questions ,, but again first  Onan and want to take care of it the right way..thanks for all your help fellas ,, hopefully i can return the favor someday...

Edited March 13, 2016 by Phatboy

[Retired Wrencher 5,438]

 

This is not my area but thinking about it is maintenance. Buy removing the shrouds at a couple time a year and blow it out. If you heavy mowing  like an acre or more. Simple  P.M. to make live and run longer.  Gary    B...

[AMC RULES 37,125]

[Theroundhousernr 589]

   Never ever squirt water on a hot engine. Specially an aluminum block! An air nozzle like craig has shown works good. I recommend pulling the engine and shields for the first time under your ownership and clean with oven cleaner or cans of carb cleaner and some brushes. Once you get it clean , you can keep it clean after each mowing with the nozzle. I run the tractor at full throttle while blowing in every nook and cranny so the flywheel air movement helps flush the stuff out of the engine. 

 

   One of the biggest issues is the mixture of oil and grass becoming a nice tar like mess over the cooling fins. Which is why I recommend to pull the tins and do it right the first time because you can not simply blow that stuff off. Pulling the engine is just a few more bolts and makes life much easier.  However, with yours being a low hour machine you might not have to do that. You can pull the charging regulator and/or oil filter on the engine and shine in with a flash light and check on the condition of the cooling fins that way.

 

  On the other hand , even though its a low hour machine. Most of the mess and oil comes from a loose oil filter and/or a sloppy done oil change. I like to jack up the front of the tractor as high as i can. Put some aluminum foil under the sheet metal thats under the oil filter to direct the oil out from the tins and cooling fins before even loosening the oil filter.

 

  I am on my fourth onan and I am getting a little tired of cleaning the fins and pulling the engine but I think its time well spent. I didnt have to clean much on my 416H so I never pulled the engine. Also think that valve adjustments on these onans is just as important.

 

 

    Hope that helps some.

 

 

[AMC RULES 37,125]

 

 

[Theroundhousernr 589]

Oh man, craig that is some kind of scary lol. Even more scary that some people would just blow some air in there or no air at all and keep running it wondering what that funny burning smell is.

Edited March 13, 2016 by Theroundhousernr

[AMC RULES 37,125]

...and wonder why thier Series1 C-175 blew up.  

[Theroundhousernr 589]

Onan P220 off my 520HC. Before and after shots. I should think yours wont look this bad but very possible and worth checking into.

[Black64galaxie 65]

Looks like a mouse taj mahal !!!!

[ericj 1,578]

people give the onan's a bad rap for valve seats and blown rods on the back cylinders, but when they change the oil they don't wipe all of the excess and spilled oil off around the the filter area and or do not tighten the filters up causing leaks, which when this happens however it happens, the flywheel throws it all over the block and all around and then pull grass and dirt in and puts a real good insulation all over the block which causes the over heating of the engine. or they don't clean up off the flywheel screen where the grass and leaves builds up and blocks the air flow causing engine to over heat. I've found most of the blown onans that I've picked up for parts have been coated pretty bad with oil and dirt. Here are some pictures of an 18 hp onan off a 518 that i picked up, amazingly it still ran but did smoke a little

 

 

 

eric j    

[Black64galaxie 65]

I just bought my first 520 h.a few months ago and the charging system wasn't working. I took off the flywheel to fix it and put a stator in it and ya your right lots a crud 

[cleat 5,771]

The 416H I bought last year had a large mouse nest blocking airflow to the front cylinder.

 

I have never had a mouse nest form in a tractor in my yard yet but I always check to be sure.

 

No air cooled engine will last long with it's cooling fins blocked off.

[MalMac 1,331]

Onan is a good motor for what it was designed for. This particular motor was not designed to work in dirty environment such as lawn mowing. Dirt and dust is one thing, dirt dust and grass clippings is another. Usually you find this motor in generator service. Not saying some gen service is not dirty. Usually gen service does not battle grass.

[Ed Kennell 37,988]

All good advice above.  I'll just add my .   

   I believe the two things that really contribute to the crud build up on the rear cylinder cooling fins are ;

1. The air flow is restricted by the belt guard.     Vent the belt guard.

2. Like others have pointed out, oil leaks keep the fins wet and sticky causing the grass to collect. In addition to  the improperly installed filter, the base plate  that the filter screws into also has a history of leaking. It is bolted to the block with only two bolts.  While you have the tins off, remove the  oil filter base plate and replace the gasket and torque the bolts properly.

Edited March 13, 2016 by ekennell

[Phatboy 565]

Well lets start by saying thos shroud is a giant pain in the behind ,, it made me so mad coming off !!! I hope i can put it back together ,, ok here is first problem,, guy put a extension out of the block to drain motor oil , and of course it is very lose and is leaking oil, and of course fan is just blowing all over the place so there was dirt and oil girme all over the engine,, used 3 cans of brake clean and have to get some more tomorro,, 1st pic os that of the home made oil drain extension,,,can some one give me an idea how to extend it correctly so it doesnt leak or come lose,, or im gonna have to put the original plug in again and deal with oil all over the place...so i have draon the brand new oil i just put in yesterday thank god i bought a gallon.so can some one show me pics of the proper way to do that please..i would be forever greatful...the top pic is that of the extended drain plug unfortunatly it posted upside down,,

[Ed Kennell 37,988]

My 520 had the same 90 degree ell that was loose and leaked. Since I didn't have room to swing the elbow to tighten or remove it, I cut the pipe nipple off between the ell and the block and installed a new nipple and a cap. now I can keep the nipple and cap tight.  To drain the oil, I make a Vee trough from aluminum foil to channel the oil into the drain pan.  I can't get a pic with the cab in place.

[cleat 5,771]

Extension with the 90 degree elbow and pipe cap is actually a factory setup.

 

If it comes loose, all you can do is disassemble it then reassemble using teflon tape or teflon pipe joint compound snugging every joint as you go.

 

[Theroundhousernr 589]

That actually is the original drain for the oil. It is suppose to make a 90 degree turn and dump out right next to the foot rest on the flywheel side. Trying to remove the tins is a giant pain in the rear when installed on the tractor and also you end up with brake clean on your nice paint. Also, it may be possible to tighten that oil drain on the tractor but I would tell you to remove the engine to tighten it and reinstall it with some sealer on the threads. Good luck and ask away with any questions

[cheesegrader 433]

Ekennell is right.

Vent the belt guard so air can flow across the rear cylinder and fix the oil leaks, or you will be forever cleaning matted grass out of your tin.

A soft plastic funnel will twist into place under the drain plug.  It helps keep the oil in the drain pan where it belongs, and off the frame and mount plate.

 

[AMC RULES 37,125]

[Theroundhousernr 589]

36 minutes ago, AMC RULES said:

 

 

  Well I'll be dipped in dog sh*t..... Never saw that one.

Edited March 13, 2016 by Theroundhousernr