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GATJcampers's avatar
GATJcampers
Explorer
Feb 18, 2015

oil in air filter for generator

I was camping in the desert with my generator (onan microquiet 4000 with 224 hours)when it suddenly died. I have a toyhauler and it was about 90 degrees and it wasn't under a large load. So i opened the compartment everything appeared to be fine. I figured I would check the air filter, so I cracked the filter housing wing nut and bam out pours some oil.? all told about 1/4 to 1/2 cup came out. the filter had oil on it, not a lot but some. cleaned it all up and it ran fine. Why was there so much oil in the filter housing? any ideas? There is a breather tube from the valve cover to the air filter housing but is it supposed to put that much oil out? any ideas? Thanks in advance

17 Replies

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  • nevadanick's avatar
    nevadanick
    Explorer
    Feb 19, 2015
    Check the exhaust to make sure its not plugged. Could be as simple as the spark arrestor screen needing cleaned if it has one.
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Feb 18, 2015
    I was waiting for one of the generator guys to chime in, but I'll swear there is a reed valve in there somewhere in the crankcase breather that can get stuck.
    I could well be wrong though- that's not my forte...
  • GATJcampers's avatar
    GATJcampers
    Explorer
    Feb 18, 2015
    the oil level is right in the middle of full and add. i don't oil the filter it's supposed to be dry(my understanding). I have done regular maintenance on it. I'm baffeled
  • mabynack's avatar
    mabynack
    Explorer II
    Feb 18, 2015
    Devocamper wrote:
    Not sure about your onan but some air filters are treated with oil even the honda 2000I's soak the air filter in oil then squeeze out thethe excess oil. Did you have it serviced and maybe they got a little carried away with the oil? I know the K&N air filters also get treated with oil. Check your owners manual for the onan.


    I use to work as a mechanic back in the 70s and many of the engines used oil bath air cleaners. I know that K&N use to use an oil bath system on their air cleaners. It's very efficient at filtering fine dust.
  • Devocamper's avatar
    Devocamper
    Explorer
    Feb 18, 2015
    Not sure about your onan but some air filters are treated with oil even the honda 2000I's soak the air filter in oil then squeeze out thethe excess oil. Did you have it serviced and maybe they got a little carried away with the oil? I know the K&N air filters also get treated with oil. Check your owners manual for the onan.
  • Sandia_Man's avatar
    Sandia_Man
    Explorer II
    Feb 18, 2015
    Sounds odd to me as well. Our Onan 4K unit has 800 hours and has run flawlessly for the 8 years we have owned our TH. I do all the maintenance and have never seen that much oil in the air filter. Since this Onan does not have an oil filter and utilizes splash lubrication maybe there was too much oil and some just happen to get into air filter.

    Glad you got it working and it's back to running fine. We've used our Onan during hotter weather than you stated powering entire rig including AC and she purrs along happily for many hours without issue. Great feeling knowing we can power our entire rig when boondocking with a simple press of a button.
  • azrving's avatar
    azrving
    Explorer
    Feb 18, 2015
    Was it overfilled by chance? Has it been serviced lately? No, it should not be putting oil in there.

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