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| [GMCnet] Onan Front Seal [message #290210] |
Wed, 11 November 2015 11:08  |
emerystora
Messages: 4442
Registered: January 2004
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In August 2014 I had reported on a front seal for the Onan 6000. I had ordered an Onan seal on ebay and installed it. National 470162R or SKF11806.
The problem is that I installed it and it started to leak badly on the first trip. The Onan package was very yellowed and it was probably very old stock.
I recently checked with a local branch of a national bearing company and they told me that seal was a single lip viton seal and a much better one for the application was a double lip nitrile seal.
This would be CR SKF 11801. I have ordered a couple of them and they will be here within a week. $8.00 each.
If any of you wrote the old number down you should substitute the new number in your records.
I have advised Kim Weeks to put this new number in the GMCMI Parts Interchange.
Emery Stora
77 Kingsley
Frederick, CO
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| Re: [GMCnet] Onan Front Seal [message #290211 is a reply to message #290210] |
Wed, 11 November 2015 11:23  |
James Hupy
Messages: 6806
Registered: May 2010
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Emery and all, the Onan is an opposed twin, the crank throws are 180
degrees apart. As one piston descends downward towards the crankcase, the
other moves upwards. If the engine is in good shape, AND, the breather on
the valve cover is working properly, the engines SHOULD be almost oil
tight. If there is blowby from the rings, then the best seals and gaskets
in the world will not keep them from throwing oil out. Leaky seals on an
onan is an early warning sign that a ring job is needed. Long periods of
inactivity, like most Gen Sets see, will cause rapid ring wear on startup.
Nature of the beast, I guess. Cure? Run it long enough to warm up the oil
frequently. Every 30 days or so. Keep clean Oil in the crankcase. Insure
that the valve cover breather check valve is functional. They are
engineered for 2500 hours of service life on the Iron block engines. But
infrequent use will easily cut that in half. Just my experience from 30+
years of working on them.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Wed, Nov 11, 2015 at 9:08 AM, Emery Stora wrote:
> In August 2014 I had reported on a front seal for the Onan 6000. I had
> ordered an Onan seal on ebay and installed it. National 470162R or
> SKF11806.
> The problem is that I installed it and it started to leak badly on the
> first trip. The Onan package was very yellowed and it was probably very
> old stock.
>
> I recently checked with a local branch of a national bearing company and
> they told me that seal was a single lip viton seal and a much better one
> for the application was a double lip nitrile seal.
> This would be CR SKF 11801. I have ordered a couple of them and they will
> be here within a week. $8.00 each.
>
> If any of you wrote the old number down you should substitute the new
> number in your records.
>
> I have advised Kim Weeks to put this new number in the GMCMI Parts
> Interchange.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Onan Front Seal [message #290229 is a reply to message #290211] |
Wed, 11 November 2015 18:04 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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James Hupy wrote on Wed, 11 November 2015 12:23Emery and all, the Onan is an opposed twin, the crank throws are 180 degrees apart. As one piston descends downward towards the crankcase, the other moves upwards. If the engine is in good shape, AND, the breather on the valve cover is working properly, the engines SHOULD be almost oil tight. <snip>
Jim Hupy
Jim,
As much as respect what you write, you got part of this one wrong.
You are correct that the throws are 180° out, but so are the cylinder bores.
In engine terms, the cylinders are 360° out.
So, both pistons are going up and down at the same time. That is why they can get by with one set of points.
That is also why the flat Onans all have a complex breather system with reed valves and such.
Matt - Still a fan
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Onan Front Seal [message #290232 is a reply to message #290229] |
Wed, 11 November 2015 18:14 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Matt,
Boy this REALLY confused me! I had to think about it real hard then I added the words below and it made sense.
Did I get it right?
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Matt Colie
Jim,
As much as respect what you write, you got part of this one wrong.
You are correct that the throws are 180° out, but so are the cylinder bores.
In engine terms, the cylinder TIMING IS 360° out.
So, both pistons are going up and down at the same time. That is why they can get by with one set of points.
That is also why the flat Onans all have a complex breather system with reed valves and such.
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Onan Front Seal [message #290260 is a reply to message #290232] |
Thu, 12 November 2015 08:50 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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O.K. Chalk that one up to a temporary brain fart. I didn't make that come
out right on my cell phone. There is a huge pressure/vacuum exchange in
opposed engines. The seals, gaskets, breathers, rings, valves, all have to
be in very good condition, or they leak. I did a very poor job of
describing what goes on. Old stock dried up seals are not worth your time
to install. The double lipped viton or neoprene seals will stop that source
of leakage. But, my original statement stands. If the rings are shot, they
leak oil.
Jim Hupy (in Canada visiting Dwayne Jacobson)
On Nov 11, 2015 4:14 PM, "Robert Mueller" wrote:
> Matt,
>
> Boy this REALLY confused me! I had to think about it real hard then I
> added the words below and it made sense.
>
> Did I get it right?
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Matt Colie
>
> Jim,
>
> As much as respect what you write, you got part of this one wrong.
> You are correct that the throws are 180° out, but so are the cylinder
> bores.
> In engine terms, the cylinder TIMING IS 360° out.
> So, both pistons are going up and down at the same time. That is why they
> can get by with one set of points.
> That is also why the flat Onans all have a complex breather system with
> reed valves and such.
>
> Matt
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Onan Front Seal [message #290261 is a reply to message #290210] |
Thu, 12 November 2015 08:58 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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On Thursday, November 12, 2015, James Hupy wrote:
> O.K. Chalk that one up to a temporary brain fart. I didn't make that come
> out right on my cell phone. There is a huge pressure/vacuum exchange in
> opposed engines. The seals, gaskets, breathers, rings, valves, all have to
> be in very good condition, or they leak. I did a very poor job of
> describing what goes on. Old stock dried up seals are not worth your time
> to install. The double lipped viton or neoprene seals will stop that source
> of leakage. But, my original statement stands. If the rings are shot, they
> leak oil.
Say hi to duwane
I think of them every day
> Jim Hupy (in Canada visiting Dwayne Jacobson)
> On Nov 11, 2015 4:14 PM, "Robert Mueller" > wrote:
>
>> Matt,
>>
>> Boy this REALLY confused me! I had to think about it real hard then I
>> added the words below and it made sense.
>>
>> Did I get it right?
>>
>> Regards,
>> Rob M.
>> The Pedantic Mechanic
>>
>> -----Original Message-----
>> From: Matt Colie
>>
>> Jim,
>>
>> As much as respect what you write, you got part of this one wrong.
>> You are correct that the throws are 180° out, but so are the cylinder
>> bores.
>> In engine terms, the cylinder TIMING IS 360° out.
>> So, both pistons are going up and down at the same time. That is why
> they
>> can get by with one set of points.
>> That is also why the flat Onans all have a complex breather system with
>> reed valves and such.
>>
>> Matt
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Onan Front Seal [message #290262 is a reply to message #290261] |
Thu, 12 November 2015 09:35 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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I'll have more to say about Dwayne when I get Stateside. He is hanging in
there. If the stars and planets align correctly, he and Sharon will be at
the Christmas Rally in Bonny Lake, Wa. on the weekend of the 5th of
December.
Jim Hupy
On Thu, Nov 12, 2015 at 6:58 AM, gene Fisher wrote:
> On Thursday, November 12, 2015, James Hupy wrote:
>
>> O.K. Chalk that one up to a temporary brain fart. I didn't make that come
>> out right on my cell phone. There is a huge pressure/vacuum exchange in
>> opposed engines. The seals, gaskets, breathers, rings, valves, all have
> to
>> be in very good condition, or they leak. I did a very poor job of
>> describing what goes on. Old stock dried up seals are not worth your time
>> to install. The double lipped viton or neoprene seals will stop that
> source
>> of leakage. But, my original statement stands. If the rings are shot,
> they
>> leak oil.
>
>
>
> Say hi to duwane
> I think of them every day
>
>
>> Jim Hupy (in Canada visiting Dwayne Jacobson)
>> On Nov 11, 2015 4:14 PM, "Robert Mueller" > > wrote:
>>
>>> Matt,
>>>
>>> Boy this REALLY confused me! I had to think about it real hard then I
>>> added the words below and it made sense.
>>>
>>> Did I get it right?
>>>
>>> Regards,
>>> Rob M.
>>> The Pedantic Mechanic
>>>
>>> -----Original Message-----
>>> From: Matt Colie
>>>
>>> Jim,
>>>
>>> As much as respect what you write, you got part of this one wrong.
>>> You are correct that the throws are 180° out, but so are the cylinder
>>> bores.
>>> In engine terms, the cylinder TIMING IS 360° out.
>>> So, both pistons are going up and down at the same time. That is why
>> they
>>> can get by with one set of points.
>>> That is also why the flat Onans all have a complex breather system with
>>> reed valves and such.
>>>
>>> Matt
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Onan Front Seal [message #290264 is a reply to message #290210] |
Thu, 12 November 2015 10:23 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Yes as any boxer, VW, Porsche,Subaru, the opposing motion creates a balanced inertial cancellation. But with only 2 cyl creates some interesting pumping action in the crankcsse
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Onan Front Seal [message #290281 is a reply to message #290232] |
Thu, 12 November 2015 19:18 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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USAussie wrote on Wed, 11 November 2015 19:14Matt,
Boy this REALLY confused me! I had to think about it real hard then I added the words below and it made sense.
Did I get it right?
Regards,
Rob M.
The Pedantic Mechanic
Rob,
That is not in-correct, but it might lead one to think that only the ignition timing is 360° out.
Maybe what I should have written was that the cylinder CYCLES were out 360 of a 720° cycle.
Glad you got it in any case.
Matt
Quote: From: Matt Colie
Jim,
As much as respect what you write, you got part of this one wrong.
You are correct that the throws are 180° out, but so are the cylinder bores.
In engine terms, the cylinder TIMING IS 360° out.
So, both pistons are going up and down at the same time. That is why they can get by with one set of points.
That is also why the flat Onans all have a complex breather system with reed valves and such.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Onan Front Seal [message #290304 is a reply to message #290281] |
Fri, 13 November 2015 16:55 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Matt,
I'll try again:
Cycles are Intake, Compression, Power, and Exhaust, therefore when cylinder #1 (left side as you face the Onan) is at Top Dead
Center on the Compression stroke cylinder #2 is at top dead center on the Intake stroke.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Matt Colie
Sent: Friday, November 13, 2015 12:18 PM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Onan Front Seal
USAussie wrote on Wed, 11 November 2015 19:14
> Matt,
>
> Boy this REALLY confused me! I had to think about it real hard then I added the words below and it made sense.
>
> Did I get it right?
>
> Regards,
> Rob M.
> The Pedantic Mechanic
Rob,
That is not in-correct, but it might lead one to think that only the ignition timing is 360° out.
Maybe what I should have written was that the cylinder CYCLES were out 360 of a 720° cycle.
Glad you got it in any case.
Matt
Quote:
> From: Matt Colie
>
> Jim,
>
> As much as respect what you write, you got part of this one wrong.
> You are correct that the throws are 180° out, but so are the cylinder bores.
> In engine terms, the cylinder TIMING IS 360° out.
> So, both pistons are going up and down at the same time. That is why they can get by with one set of points.
> That is also why the flat Onans all have a complex breather system with reed valves and such.
>
> Matt
--
Matt & Mary Colie - Members GMCMI, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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