Oil sputtering (4K) Onan

[peer oliver schmidt]

Morning,

my 23' is on its maiden voyage, and after some quad carb (part)rebuilt
the 455 runs much better. However the Onan doesn't like to keep its oil.

Anyone has an idea?

Quote: Oil sputtering out of the cap which doesn't appear to screw on
like the other one and the oil rebreather going into the carb
http://possy.de/onan1.jpg

After two minutes of running, there is a sizable amount of oil on the
tarmac. http://possy.de/onan2.jpg

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, CA
'73 Sequoia, VA

 

[dennis sexton]

Peer

Not an uncommon problem on the 4KW. The rubber plug seal on the oil dipstick gets loose and blows oil out the top.
You can try turning the dipstick handle so that the curl handle wedges against the exhaust manifolsd.
Or you can put a couple of wraps of tape around the rubber seal to help it fit more snugly.

Dennis

> Morning,
>
> my 23' is on its maiden voyage, and after some quad carb (part)rebuilt
> the 455 runs much better. However the Onan doesn't like to keep its oil.
>
> Anyone has an idea?
>
> Quote: Oil sputtering out of the cap which doesn't appear to screw on
> like the other one and the oil rebreather going into the carb
> http://possy.de/onan1.jpg
>
> After two minutes of running, there is a sizable amount of oil on the
> tarmac. http://possy.de/onan2.jpg
>
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II, CA
> '73 Sequoia, VA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Dennis S
73 Painted Desert 230
Memphis TN Metro

 

[dennis sexton]

Peer

Also check this old thread for possible cures.

http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=302972&rid=904&srch=Onan+4KW+blowing+oil+out

Dennis

> Peer
>
> Not an uncommon problem on the 4KW. The rubber plug seal on the oil dipstick gets loose and blows oil out the top.
> You can try turning the dipstick handle so that the curl handle wedges against the exhaust manifolsd.
> Or you can put a couple of wraps of tape around the rubber seal to help it fit more snugly.
>
> Dennis
>

> > Morning,
> >
> > my 23' is on its maiden voyage, and after some quad carb (part)rebuilt
> > the 455 runs much better. However the Onan doesn't like to keep its oil.
> >
> > Anyone has an idea?
> >
> > Quote: Oil sputtering out of the cap which doesn't appear to screw on
> > like the other one and the oil rebreather going into the carb
> > http://possy.de/onan1.jpg
> >
> > After two minutes of running, there is a sizable amount of oil on the
> > tarmac. http://possy.de/onan2.jpg
> >
> > --
> > Best regards
> >
> > Peer Oliver Schmidt
> > PGP Key ID: 0x83E1C2EA
> >
> > '76a Eleganza II, CA
> > '73 Sequoia, VA
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Dennis S
73 Painted Desert 230
Memphis TN Metro

 

[Matt Colie]

Peer,

As you may have read in the prior post, I was to have that exact same problem.
I can report a successful cure.

If you wrap the rubber part of the dipstick with several (I do not recall what it took) layers of teflon tape, you can make the plug hold in the tube
again. The first time I tried this, I did not clean the rubber stopper off well enough and the tape slipped off. When I wrapped it up after
cleaning, the tape has been on there about an hundred hours now.
Before I did that, I got an expandable rubber plug that did work in the place, but it was then a major PITA to check the lube oil level.

There is (or at least I could not locate) a replacement part. The later version use a stick that is attached to a bayonet closed cap. That is what
my other BF has, but I have investigating swapping because I do not want to disable that unit.

The next problem you will have (another hundred hours or so) is that the swaging that stops the indicator from going through the plate on top of the
rubber stopper will wear off and the stick goes though. This is can be a big issue, but fortunately, I had just changed the oil and KNEW it was not
over full. It could have been a disaster if the lube oil level had gotten that low and I did not catch it.

I had lots of plans to repair this when I found it, but not time. So, I put a tight wrap of safety wire on the stick and will engineer a better
repair during the winter layup that is all too close now.

Matt - In Paducah with GMCES and GMCGL waiting for the sky to go dark.

> Morning,
> my 23' is on its maiden voyage, and after some quad carb (part)rebuilt
> the 455 runs much better. However the Onan doesn't like to keep its oil.
>
> Anyone has an idea?
>
> Quote: Oil sputtering out of the cap which doesn't appear to screw on
> like the other one and the oil rebreather going into the carb
> http://possy.de/onan1.jpg
>
> After two minutes of running, there is a sizable amount of oil on the
> tarmac. http://possy.de/onan2.jpg
>
> --
> Best regards
>
> Peer Oliver Schmidt
> '76a Eleganza II, CA
> '73 Sequoia, VA

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[peer oliver schmidt]

Matt,

did you ever try fixing the probable cause, ie. the not working breather
hose?

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, CA
'73 Sequoia, VA

 

[Matt Colie]

> Matt,
>
> did you ever try fixing the probable cause, ie. the not working breather
> hose?
>
> --
> Best regards
> e
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II, CA
> '73 Sequoia, VA

Peer,

Funny you should mention that. I thought that this was an indicator of an engine problem.
So, I did a cylinder leak check first.
That was good (pretty good really).
Then I set up to actually measure the crackcase pressure. (I was an engine lab rat for decades.) This was exciting because it alternated between
blowing the water out of the manometer and sucking it into the crankcase.
This was at the dipstick/lube oil fill. I gave up on that and put the manometer down stream of the crankcase reed valves.
That was almost disappointing - Nothing there.
With new orifice and a Magnahelic (expensive manometer) I finally got a reasonable blow-by measurement at power required for the A/C, the water heater
and the microware (How's that for a load bank?) to be a quarter of a CFM.

Then, the LED in my brain lit (only recently upgraded from incandescent) and I realizsd that the with the engine being an opposed twin, it has to have
immense crankcase volume and therefore pressure fluctuations and there is nothing to be done, but live with it.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[peer oliver schmidt]

Matt,

thanks for your explanation. Forwarded to my friend, he likes your text

--
Best regards

Peer Oliver Schmidt
the internet company
PGP Key ID: 0x83E1C2EA

 

[dennis sexton]

Peer/Matt

Another old thread talking about the pressure generated by the engine design with the cylinders operating on the same cycle.

http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=24185&rid=904&srch=Onan+oil+dipstick+blow

Dennis

> > Matt,
> >
> > did you ever try fixing the probable cause, ie. the not working breather
> > hose?
> >
> > --
> > Best regards
> > e
> > Peer Oliver Schmidt
> > PGP Key ID: 0x83E1C2EA
> >
> > '76a Eleganza II, CA
> > '73 Sequoia, VA
>
> Peer,
>
> Funny you should mention that. I thought that this was an indicator of an engine problem.
> So, I did a cylinder leak check first.
> That was good (pretty good really).
> Then I set up to actually measure the crackcase pressure. (I was an engine lab rat for decades.) This was exciting because it alternated between
> blowing the water out of the manometer and sucking it into the crankcase.
> This was at the dipstick/lube oil fill. I gave up on that and put the manometer down stream of the crankcase reed valves.
> That was almost disappointing - Nothing there.
> With new orifice and a Magnahelic (expensive manometer) I finally got a reasonable blow-by measurement at power required for the A/C, the water
> heater and the microware (How's that for a load bank?) to be a quarter of a CFM.
>
> Then, the LED in my brain lit (only recently upgraded from incandescent) and I realizsd that the with the engine being an opposed twin, it has to
> have immense crankcase volume and therefore pressure fluctuations and there is nothing to be done, but live with it.
>
> Matt

--
Dennis S
73 Painted Desert 230
Memphis TN Metro