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Onan blowing oil

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  • GeorgeG
    All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I
    Message 1 of 11 , Oct 10, 2010
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      All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
      I believe I saw links to reapir info but can't find them.
      Thanks,
      GEORGE!!
    • james kendall
      well.....I am no expert, but here are my three cents (inflation): An outright bad seal usually leaks, engine running or not. I am assuming you are getting high
      Message 2 of 11 , Oct 11, 2010
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        well.....I am no expert, but here are my three cents (inflation):

        An outright bad seal usually leaks, engine running or not.

        I am assuming you are getting high crankcase pressure, which is pushing oil out
        through the seal.
        IF it only leaks with engine running:
          perhaps a stuck / broken ring
           OR stuck valve.

        any of these will show up with a compression test. Usuall only one cylinder fails at a time.
        a broken ring is *bad* .... will eventually tear  up  cylinder walls beyond repair.
        so there IS a gamble with running it.

        First, drain oil through a nice rag, you are looking for metal.
        Any metal, you're done, probably broken ring, take it out and tear it down.

        Put some oil back in....a quart or two....

                procedure:
        top off with good old Marvel Mystery oil.
        ( not cheap, but I've had good luck with it)
        Start it up and run till hot......or you get strange noises.
        If you get strange noises.....your done...take it out & apart.
        stop...let it cool
          
        drain oil thru cloth into clean bucket....again look for oil or anything weird.
        put the oil back into the generator.
               repeat procedure three or four times.

        If it's getting better (less leakage) you're probably good to go.
        Stays the same....perhaps broken ring, or cylinder corrosion.

        Might get a little worse for a while, as M.Mystery Oil is pretty thin.
        So take that into account while checking.

        Just   a little corrosion can make  a seal look bad, and if yours was sitting for a while, you just might luck out.

        Jim







        [Non-text portions of this message have been removed]
      • gmmullins4
        while some are easy to work on, if yours is encased in a box you will have to remove it to work on it. it could be a seal on the crank but could also be the
        Message 3 of 11 , Oct 11, 2010
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          while some are easy to work on, if yours is encased in a box you will have to remove it to work on it. it could be a seal on the crank but could also be the rubber plug that lets crankcase air into the carb has come off, it has a baffle in it to stop oil from coming out of it. both could cause a problem with oil, as the crankcase is a positive flow type case.

          --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@...> wrote:
          >
          > All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
          > I believe I saw links to reapir info but can't find them.
          > Thanks,
          > GEORGE!!
          >
        • Ted Kroll
          Sure seems like a lot of trouble, crankcase pressure sure could cause this. If that is indicated I believe just try loosing the oil fill cap and run. Ted ...
          Message 4 of 11 , Oct 12, 2010
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            Sure seems like a lot of trouble, crankcase pressure sure could cause this. If that is indicated I believe just try loosing the oil fill cap and run.
            Ted
            ----- Original Message -----
            From: james kendall
            To: classicrv@yahoogroups.com
            Sent: Monday, October 11, 2010 4:26 PM
            Subject: [classicrv] Onan blowing oil



            well.....I am no expert, but here are my three cents (inflation):

            An outright bad seal usually leaks, engine running or not.

            I am assuming you are getting high crankcase pressure, which is pushing oil out
            through the seal.
            IF it only leaks with engine running:
            perhaps a stuck / broken ring
            OR stuck valve.

            any of these will show up with a compression test. Usuall only one cylinder fails at a time.
            a broken ring is *bad* .... will eventually tear up cylinder walls beyond repair.
            so there IS a gamble with running it.

            First, drain oil through a nice rag, you are looking for metal.
            Any metal, you're done, probably broken ring, take it out and tear it down.

            Put some oil back in....a quart or two....

            procedure:
            top off with good old Marvel Mystery oil.
            ( not cheap, but I've had good luck with it)
            Start it up and run till hot......or you get strange noises.
            If you get strange noises.....your done...take it out & apart.
            stop...let it cool

            drain oil thru cloth into clean bucket....again look for oil or anything weird.
            put the oil back into the generator.
            repeat procedure three or four times.

            If it's getting better (less leakage) you're probably good to go.
            Stays the same....perhaps broken ring, or cylinder corrosion.

            Might get a little worse for a while, as M.Mystery Oil is pretty thin.
            So take that into account while checking.

            Just a little corrosion can make a seal look bad, and if yours was sitting for a while, you just might luck out.

            Jim

            [Non-text portions of this message have been removed]





            [Non-text portions of this message have been removed]
          • mcolie
            George, Of course it is coming out the fan. That fan pulls air over most of the engine, so a leak anywhere gets sucked up and blown out the fan. There are
            Message 5 of 11 , Oct 12, 2010
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              George,

              Of course it is coming out the fan. That fan pulls air over most of the engine, so a leak anywhere gets sucked up and blown out the fan.

              There are many versions of Onan out there. It would be helpful to know what version you have and the year build would be good too.

              There are Onan service docs all over the place, but you have to know the model you are looking for.

              If it is one of the flat twin versions, then there are two common mode failures from 20+ years ago. One is the LOP switch (a replacement from NAPA is ~12$). The other is the two gaskets under the oil filter mount (replacements cost ~12$). Both can be accessed under the engine side cover. Neither is easy, but they can be done with the APU pulled out the sides.

              Matt



              --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@...> wrote:
              >
              > All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
              > I believe I saw links to reapir info but can't find them.
              > Thanks,
              > GEORGE!!
              >
            • james kendall
              ... From: Ted Kroll Subject: Re: [classicrv] Onan blowing oil To: classicrv@yahoogroups.com Date: Tuesday, October 12, 2010, 9:21 AM
              Message 6 of 11 , Oct 12, 2010
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                --- On Tue, 10/12/10, Ted Kroll <tedkroll@...> wrote:

                From: Ted Kroll <tedkroll@...>
                Subject: Re: [classicrv] Onan blowing oil
                To: classicrv@yahoogroups.com
                Date: Tuesday, October 12, 2010, 9:21 AM







                 









                Sure seems like a lot of trouble, crankcase pressure sure could cause this. If that is indicated I believe just try loosing the oil fill cap and run.

                Ted

                Yeah, you ould, s a test, bt, if it gets too loose, you will gush oil out through the fill screw.Just a hair loose should do it, but it  might dance itself loose over the course of an hour or so.Jim
                .





















                [Non-text portions of this message have been removed]
              • GeorgeG
                ... It is a CCK from the late 70 s No oil filter so that is out. Were is the LOP swith? I am a mechanic so I know all the basic stuff just not very familar
                Message 7 of 11 , Oct 13, 2010
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                  --- In classicrv@yahoogroups.com, "mcolie" <mattcolie@...> wrote:
                  >
                  > Matt,
                  It is a CCK from the late 70's No oil filter so that is out.
                  Were is the LOP swith?
                  I am a mechanic so I know all the basic stuff just not very familar with the Onan. I don't feel a lot of pressure at the vent up top going to the carb so I doubt too much crank pressure and the crank seal in not submerged in oil when it is not running.
                  I will go with the switch idea just have to find it.
                  Thanks,
                  GEORGE!!
                  >
                  >
                  > George,
                  >
                  > Of course it is coming out the fan. That fan pulls air over most of the engine, so a leak anywhere gets sucked up and blown out the fan.
                  >
                  > There are many versions of Onan out there. It would be helpful to know what version you have and the year build would be good too.
                  >
                  > There are Onan service docs all over the place, but you have to know the model you are looking for.
                  >
                  > If it is one of the flat twin versions, then there are two common mode failures from 20+ years ago. One is the LOP switch (a replacement from NAPA is ~12$). The other is the two gaskets under the oil filter mount (replacements cost ~12$). Both can be accessed under the engine side cover. Neither is easy, but they can be done with the APU pulled out the sides.
                  >
                  > Matt
                  >
                  >
                  >
                  > --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@> wrote:
                  > >
                  > > All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
                  > > I believe I saw links to reapir info but can't find them.
                  > > Thanks,
                  > > GEORGE!!
                  > >
                  >
                • GeorgeG
                  Thanks Matt, the switch got it. I thought they had a low oil level switch not pressure. I pulled the side cover off and there was my oiley switch. Next I
                  Message 8 of 11 , Oct 13, 2010
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                    Thanks Matt, the switch got it. I thought they had a low oil level switch not pressure. I pulled the side cover off and there was my oiley switch.
                    Next I called my parts store which is a NAPA and also has a small engine dept. After about 1/2 hr he tells me Onan shows it as an option and is $80. Maybe he found a double switch that also does a gauge. Well not me. I went back in the shop and pulled a box of new switches. They were a sorta universal units with a bolt on spade adopter. Changed it ran the engine, not a drop in 15 min.
                    Thanks again.
                    GEORGE!!

                    --- In classicrv@yahoogroups.com, "mcolie" <mattcolie@...> wrote:
                    >
                    >
                    >
                    >
                    > George,
                    >
                    > Of course it is coming out the fan. That fan pulls air over most of the engine, so a leak anywhere gets sucked up and blown out the fan.
                    >
                    > There are many versions of Onan out there. It would be helpful to know what version you have and the year build would be good too.
                    >
                    > There are Onan service docs all over the place, but you have to know the model you are looking for.
                    >
                    > If it is one of the flat twin versions, then there are two common mode failures from 20+ years ago. One is the LOP switch (a replacement from NAPA is ~12$). The other is the two gaskets under the oil filter mount (replacements cost ~12$). Both can be accessed under the engine side cover. Neither is easy, but they can be done with the APU pulled out the sides.
                    >
                    > Matt
                    >
                    >
                    >
                    > --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@> wrote:
                    > >
                    > > All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
                    > > I believe I saw links to reapir info but can't find them.
                    > > Thanks,
                    > > GEORGE!!
                    > >
                    >
                  • gmmullins4
                    onan or i should say cummins/onan would have that part for you, it was an option for a gauge switch on some units, majority do not have them when installed in
                    Message 9 of 11 , Oct 30, 2010
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                      onan or i should say cummins/onan would have that part for you, it was an option for a gauge switch on some units, majority do not have them when installed in a rv. but newer units do have the pressure switch, spendy little devils



                      --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@...> wrote:
                      >
                      > Thanks Matt, the switch got it. I thought they had a low oil level switch not pressure. I pulled the side cover off and there was my oiley switch.
                      > Next I called my parts store which is a NAPA and also has a small engine dept. After about 1/2 hr he tells me Onan shows it as an option and is $80. Maybe he found a double switch that also does a gauge. Well not me. I went back in the shop and pulled a box of new switches. They were a sorta universal units with a bolt on spade adopter. Changed it ran the engine, not a drop in 15 min.
                      > Thanks again.
                      > GEORGE!!
                      >
                      > --- In classicrv@yahoogroups.com, "mcolie" <mattcolie@> wrote:
                      > >
                      > >
                      > >
                      > >
                      > > George,
                      > >
                      > > Of course it is coming out the fan. That fan pulls air over most of the engine, so a leak anywhere gets sucked up and blown out the fan.
                      > >
                      > > There are many versions of Onan out there. It would be helpful to know what version you have and the year build would be good too.
                      > >
                      > > There are Onan service docs all over the place, but you have to know the model you are looking for.
                      > >
                      > > If it is one of the flat twin versions, then there are two common mode failures from 20+ years ago. One is the LOP switch (a replacement from NAPA is ~12$). The other is the two gaskets under the oil filter mount (replacements cost ~12$). Both can be accessed under the engine side cover. Neither is easy, but they can be done with the APU pulled out the sides.
                      > >
                      > > Matt
                      > >
                      > >
                      > >
                      > > --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@> wrote:
                      > > >
                      > > > All of a sudden my Onan started dumping oil out the fan. It blows about a qt in an hour or so. I would think seal. Is this somthing I can do in the box or do I have to pull it.?
                      > > > I believe I saw links to reapir info but can't find them.
                      > > > Thanks,
                      > > > GEORGE!!
                      > > >
                      > >
                      >
                    • GeorgeG
                      Everything from them is pricey. They thing they are selling stuff to a guy with a Kenworth. I used a swithc from a car for a few bucks instead of there $60 +
                      Message 10 of 11 , Oct 31, 2010
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                        Everything from them is pricey. They thing they are selling stuff to a guy with a Kenworth. I used a swithc from a car for a few bucks instead of there $60 + part.
                        GEORGE!!

                        --- In classicrv@yahoogroups.com, "gmmullins4" <gmmullins4@...> wrote:
                        >
                        > onan or i should say cummins/onan would have that part for you, it was an option for a gauge switch on some units, majority do not have them when installed in a rv. but newer units do have the pressure switch, spendy little devils
                        >
                        >
                        >
                        >
                      • TJ
                        You might try looking for Onan parts at Sears as they used Onans in a lot of machinery they sold over the years. Sears still stocks a bunch of parts at lower
                        Message 11 of 11 , Nov 2, 2010
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                          You might try looking for Onan parts at Sears as they used Onans in a lot of machinery they sold over the years. Sears still stocks a bunch of parts at lower prices than you can find elsewhere. You might try this link... http://www.searspartsdirect.com/partsdirect/index.action?intcmp=xsite_Sears ... As I recall, the original Onan part numbers have to be played with a bit sometimes in order to come up in the Sears Parts Direct search. Last resort, give Sears a call and they will help you find the right number. Jeff 74 Travco Mahal, 6.0 Onan Genset


                          --- In classicrv@yahoogroups.com, "GeorgeG" <ustow@...> wrote:
                          >
                          > Everything from them is pricey. They thing they are selling stuff to a guy with a Kenworth. I used a swithc from a car for a few bucks instead of there $60 + part.
                          > GEORGE!!
                          >
                          > --- In classicrv@yahoogroups.com, "gmmullins4" <gmmullins4@> wrote:
                          > >
                          > > onan or i should say cummins/onan would have that part for you, it was an option for a gauge switch on some units, majority do not have them when installed in a rv. but newer units do have the pressure switch, spendy little devils
                          > >
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