520H oil in air cleaner

[SadieCoonhound 8]

My 1988 or 1989 520h is running well. However, I’ve noticed oil leaking and discovered a large amount  of oil in the air cleaner compartment. Could it be coming up from the flywheel? The oil breather?
you gentleman have always helped me in the past. Can you put your capes on again and fly to my rescue?

[Tuneup 1,452]

The big wigs on Onans will be by but I do know that the flywheel does not play a role. The timing cover breathes to the intake valve compartment and then through the breather filter. I would pull the breather filter to make sure that the fill in it that blocks the liquid and passes the vapors has not broken down. The scary thing would be that the rings are worn and the blow-by is so great that oil will get to the top. You said it runs well so I'm expecting that is not the case but these machines are not spring puppies. My 16 needs a rebuild and smokes a bit but the air cleaner interior is clean.

[lynnmor 7,815]

Pull the breather to clean and inspect it, if a previous owner assembled it poorly that could be the problem.  Check the compression to see if the basic engine is healthy.  Hold the air filter element up to a light and see if it is clogged, a restrictive air filter will cause a vacuum.

Edited October 24, 2020 by lynnmor

[SadieCoonhound 8]

Thank you guys. I will update this   

[Darb1964 1,119]

The gasket behind the oil filter is probably leaking and the oil is being sucked up through the breather. I have a 518-h that is doing the same thing, hope to get to it this winter after deer season and fall clean up.

[doc724 925]

This happened in my 416H-once.  Some Dodo (who will go un-named) put a tad more oil than necessary in the crank case during an oil change.  I had to drain off a little oil, clean up the mess in the air cleaner and put in a new paper filter element.  The problem went away.  Not saying the other posters are wrong.  I always look for the simple, low cost explanations first.

[SadieCoonhound 8]

Thanks for all your replies. Air filter is filthy, ordering a new one. Btw does Napa or fram have one that would fit? My compression tester wouldn’t hold a reading. Had to buy a new one, Does any one. Know what the proper compression should be? It’s an Onan 220G. Going to change oil and filter. Have a good nite. 

[lynnmor 7,815]

Napa has the air filter and pre-filter.  Onan manual states 75 to 115 PSI compression, be sure to download the manual.

[SadieCoonhound 8]

Thanks. Napa ordered the filter for me. Compression shows 100psi for front and 120psi at rear. This was done on a cold engine. Can I assume this is acceptable?

 

 

[SadieCoonhound 8]

Oh, and thanks for the manual. 

[lynnmor 7,815]

2 hours ago, SadieCoonhound said:

Thanks. Napa ordered the filter for me. Compression shows 100psi for front and 120psi at rear. This was done on a cold engine. Can I assume this is acceptable?

 

 

Normal, but I like to see both about the same.  Probably the lower compression cylinder has a less than perfect valve, just check regularly and if it drops below 90, I would freshen up the valves and seats.  Depending on hours, you might want to adjust the valves now.

[SadieCoonhound 8]

Thanks again for all your help, gentlemen. installed new oil filter, air filter, plugs, passed a compression test. I’ve been running it a lot lately mowing and collecting leaves and leaves and leaves. I notice oil is starting to collect again in the air filter housing. Am expecting the breather to be the cause of this. I will take it apart when I can. My other “spare” Horse is hurting so I can’t be without. 
Do you guys agree?

[lynnmor 7,815]

It doesn't take a lot of time to remove, clean and reinstall the breather, look at the manual for instructions.  If someone had worked on the breather in the past it is very possible that it was reassembled wrong.

[SadieCoonhound 8]

Thanks

[tom2p 2,394]

 

11 hours ago, lynnmor said:

It doesn't take a lot of time to remove, clean and reinstall the breather, look at the manual for instructions.  If someone had worked on the breather in the past it is very possible that it was reassembled wrong.

 

question :

should the breather be part of normal scheduled maintenance  - or is service required only when issues surface (for example : excess oil accumulating inside the air cleaner assembly) ?

 

Edited November 10, 2020 by tom2p

[tom2p 2,394]

12 hours ago, SadieCoonhound said:

Thanks again for all your help, gentlemen. installed new oil filter, air filter, plugs, passed a compression test. I’ve been running it a lot lately mowing and collecting leaves and leaves and leaves. I notice oil is starting to collect again in the air filter housing. Am expecting the breather to be the cause of this. I will take it apart when I can. My other “spare” Horse is hurting so I can’t be without. 
Do you guys agree?

how much oil is accumulating ?  
 

do you saturate the foam pre-filter with oil before installation ?

 

[SadieCoonhound 8]

Seems like about an ounce every couple of hours. But not real sure about that. I’ve been using it quite heavily lately. Mowing and pulling a lawn sweeper around collecting leaves. 
No, I did not saturate the foam pre-filter before installing. Probably should have. Although it’s saturated now from the “blow by”. 

[lynnmor 7,815]

4 hours ago, tom2p said:

 

 

question :

should the breather be part of normal scheduled maintenance  - or is service required only when issues surface (for example : excess oil accumulating inside the air cleaner assembly) ?

 

It is normal maintenance but I have never seen the need, they usually stay clean.  The problems arise from incorrect reassembly.  If the tractor in question has a good breather, a clean properly serviced air filter and is running right, then the engine may have too much blow-by.   A compression test didn't reveal a problem, so now the engine needs a leak down test to see if it is healthy.

[SadieCoonhound 8]

Well, I disassembled the breather and discovered a rather large hole in the breather tube. My first move is to replace it ASAP. Can you suggest where I can find one?
Have bought parts from the infamous Boomer before, but I haven’t spoken to him in years. 
Thanks again

[lynnmor 7,815]

If you mean the rubber hose, just take the best portion to NAPA.  If you mean metal parts, call Boomer or maybe A-Z Tractor.  I didn’t check but maybe Toro still has the parts.

[SadieCoonhound 8]

No luck at Napa. I think Boomer can help me out. I also saw them on Onan

parts.com. 
I performed a leak down test according to Boomers instructions. This is the test without the actual tester where you shoot air into each cylinder at tdc. You listen for leaks. I heard nothing so I’m feeling pretty good about it. 
You were right Lynnmor. The breather had a huge hole in it and the lower gasket had slid out of position quite a bit. I duct taped the breather tube the best I could and put it back together and drove it around a little. I’ll keep my eye on the air cleaner to see if oil appears over the next few days. And install new gaskets and hose. 
Thanks. 

[lynnmor 7,815]

13 hours ago, SadieCoonhound said:

No luck at Napa. I think Boomer can help me out. I also saw them on Onan

parts.com. 
I performed a leak down test according to Boomers instructions. This is the test without the actual tester where you shoot air into each cylinder at tdc. You listen for leaks. I heard nothing so I’m feeling pretty good about it. 
You were right Lynnmor. The breather had a huge hole in it and the lower gasket had slid out of position quite a bit. I duct taped the breather tube the best I could and put it back together and drove it around a little. I’ll keep my eye on the air cleaner to see if oil appears over the next few days. And install new gaskets and hose. 
Thanks. 

It still isn't clear to me what you found, if you could post a picture it would be worth a thousand words.

[SadieCoonhound 8]

I’m sorry that I didn’t take pictures. Everything is back together although with duct tape on the rubber breather tube. Anyway, the leak down test revealed no air escaping (if I did it right. I tried Boomers instructions.)

The valve cover gaskets were a nightmare and were out of place. I thought you may be able to tell me if the “cockeyed gaskets and the rip in the breather tune could have the oil going into my air cleaner.

You mentioned that a badly assembled oil breather could cause this original problem. Do you think I’m on the right track? Sorry, I’m not that bright at this stuff. Just addicted to my dog and my horses

[lynnmor 7,815]

It sounds like you are on the right track, but I am confused about the rubber part.  I didn’t know that system was used on the 520s.  Onan made some changes about the time yours was built, thus the need for a photo.

[SadieCoonhound 8]