GMCforum: GMCnet » Noisy Onan

Home » Public Forums » GMCnet » Noisy Onan

Show: Today's Messages :: Polls :: Message Navigator

Noisy Onan [message #333173]

Thu, 07 June 2018 12:34

Deb

Messages: 349
Registered: October 2016
Location: Logan Lake, BC

Karma: 2

Senior Member

Got the Onan running, but not well I think. Sat for 4 days after getting it back, took about 15 seconds to start (sounded like wasn't getting fuel; fine on re-start). Since I have never had it running, and haven't heard another, I can't be certain, but I don't think it should sound like this....https://www.screencast.com/t/3dRknmXzB

Oil, filter, etc all good, new fuel filter.

Of course louder than is coming up here, like a metal fan striking the housing, but more intense. Any ideas about what I'm looking at here before I take the next step? Or you tell me what that should be Wink

Thanks for your insight... I have none naturally. Deb

Deb McWade Logan Lake, BC, CAN GMC Alumnus It's Bigger on the Inside!

Report message to a moderator

Re: [GMCnet] Noisy Onan [message #333174 is a reply to message #333173]

Thu, 07 June 2018 12:41

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

The choke is kinda touchy when starting from cold. Usually, if you have a
problem on cold start, and you adjust for that, then when the unit is
warmed up, the choke is too rich. Touchy adjustment. Sometimes the ground
wire on the choke is rusty and corroded. A cleanup helps. Worth a try.
Jim Hupy

On Thu, Jun 7, 2018, 10:34 AM Deb McWade wrote:

> Got the Onan running, but not well I think. Sat for 4 days after getting
> it back, took about 15 seconds to start (sounded like wasn't getting fuel;
> fine on re-start). Since I have never had it running, and haven't heard
> another, I can't be certain, but I don't think it should sound like
> this....https://www.screencast.com/t/3dRknmXzB
>
> Oil, filter, etc all good, new fuel filter.
>
> Of course louder than is coming up here, like a metal fan striking the
> housing, but more intense. Any ideas about what I'm looking at here before
> I
> take the next step? Or you tell me what that should be ;)
>
> Thanks for your insight... I have none naturally. Deb
> --
> Deb McWade
> Logan Lake, BC, CAN
> "Li'l Sister"
> '77 Kingsley, 403, EBL EFI;
> TZE167V101404
> It's Bigger on the Inside!
>
>
> _______________________________________________
> 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

Report message to a moderator

Re: [GMCnet] Noisy Onan [message #333176 is a reply to message #333174]

Thu, 07 June 2018 12:51

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Rattle when running could be the engine mount cushions. When they fail, the
starter bracket rattles against the frame. Not too difficult to change.
Applied has them in stock.

On Thu, Jun 7, 2018, 10:41 AM James Hupy wrote:

> The choke is kinda touchy when starting from cold. Usually, if you have a
> problem on cold start, and you adjust for that, then when the unit is
> warmed up, the choke is too rich. Touchy adjustment. Sometimes the ground
> wire on the choke is rusty and corroded. A cleanup helps. Worth a try.
> Jim Hupy
>
> On Thu, Jun 7, 2018, 10:34 AM Deb McWade wrote:
>
>> Got the Onan running, but not well I think. Sat for 4 days after getting
>> it back, took about 15 seconds to start (sounded like wasn't getting fuel;
>> fine on re-start). Since I have never had it running, and haven't heard
>> another, I can't be certain, but I don't think it should sound like
>> this....https://www.screencast.com/t/3dRknmXzB
>>
>> Oil, filter, etc all good, new fuel filter.
>>
>> Of course louder than is coming up here, like a metal fan striking the
>> housing, but more intense. Any ideas about what I'm looking at here before
>> I
>> take the next step? Or you tell me what that should be ;)
>>
>> Thanks for your insight... I have none naturally. Deb
>> --
>> Deb McWade
>> Logan Lake, BC, CAN
>> "Li'l Sister"
>> '77 Kingsley, 403, EBL EFI;
>> TZE167V101404
>> It's Bigger on the Inside!
>>
>>
>> _______________________________________________
>> 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

Report message to a moderator

Re: [GMCnet] Noisy Onan [message #333177 is a reply to message #333176]

Thu, 07 June 2018 14:02

Deb

Messages: 349
Registered: October 2016
Location: Logan Lake, BC

Karma: 2

Senior Member

James Hupy wrote on Thu, 07 June 2018 10:51

Rattle when running could be the engine mount cushions. When they fail, the
starter bracket rattles against the frame. Not too difficult to change.
Applied has them in stock.

Thanks James. Sounds more like a rubbing sound than a rattle, but I will take a look at the mounts and also check the starter bracket. Hopefully something simple like that. But I don't hold my breath on anything anymore Wink

Deb McWade Logan Lake, BC, CAN GMC Alumnus It's Bigger on the Inside!

Report message to a moderator

Re: Noisy Onan [message #333178 is a reply to message #333173]

Thu, 07 June 2018 14:02

SteveW

Messages: 538
Registered: June 2005
Location: Southern California - Ora...

Karma: 1

Senior Member

On mine - the oil fill tube cap got a little loose and rattled...

I don't remember how I tightened it back up - might have been a rivet - but I know it was the source of rattling because when I pressed it into place - the rattling stopped.

Good Luck !

Steve W
1973 23' Yellow
Southern California

Steve W 1973 : 23' Southern California

Report message to a moderator

Re: Noisy Onan [message #333188 is a reply to message #333173]

Thu, 07 June 2018 17:07

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

Deb wrote on Thu, 07 June 2018 13:34

Got the Onan running, but not well I think. Sat for 4 days after getting it back, took about 15 seconds to start (sounded like wasn't getting fuel; fine on re-start). Since I have never had it running, and haven't heard another, I can't be certain, but I don't think it should sound like this....https://www.screencast.com/t/3dRknmXzB

Oil, filter, etc all good, new fuel filter.

Of course louder than is coming up here, like a metal fan striking the housing, but more intense. Any ideas about what I'm looking at here before I take the next step? Or you tell me what that should be

Thanks for your insight... I have none naturally. Deb

My Onan developed a sound just like that on my last trip. Turned out the flywheel was loose and rubbing against the front of the Onan. Made a sound just like your audio file. All I had to do was tightened the bolt back to spec and the rattle went away.

Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.

Report message to a moderator

Re: [GMCnet] Noisy Onan [message #333198 is a reply to message #333177]

Thu, 07 June 2018 17:27

Will Albers

Messages: 183
Registered: November 2017
Location: Detroit MI (Belleville)

Karma: 2

Senior Member

Running on half the engine? Pull one plug wire, see if it dies vs no change
at all.

On Thu, Jun 7, 2018, 3:12 PM Deb McWade wrote:

> James Hupy wrote on Thu, 07 June 2018 10:51
>> Rattle when running could be the engine mount cushions. When they fail,
> the
>> starter bracket rattles against the frame. Not too difficult to change.
>> Applied has them in stock.
>
>
> Thanks James. Sounds more like a rubbing sound than a rattle, but I will
> take a look at the mounts and also check the starter bracket. Hopefully
> something simple like that. But I don't hold my breath on anything
> anymore ;)
> --
> Deb McWade
> Logan Lake, BC, CAN
> "Li'l Sister"
> '77 Kingsley, 403, EBL EFI;
> TZE167V101404
> It's Bigger on the Inside!
>
>
> _______________________________________________
> 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

1978 Palm Beach.
Detroit Michigan

Report message to a moderator

Re: [GMCnet] Noisy Onan [message #333202 is a reply to message #333198]

Thu, 07 June 2018 18:33

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Will,

Pulling either plug wire will ALWAYS kill an Onan because it uses a "lost
spark" ignition system. Maybe you've noticed that there is no distributor
on its engine -- merely two high voltage wires coming out of the ignition
coil. Those wires connect to each end of the coil's secondary winding.
Since the cylinders are opposed, one is on the exhaust stroke when the
other is on the compression stroke. The impedance (call it resistance if
you like) of the mixture in the exhaust cylinder is very low, so the
ignition voltage "interprets" that as a ground connection and generates
only a low voltage drop there. Conversely, the other cylinder's highly
compressed mixture presents a high impedance, across which the ignition
coil generates a high enough voltage to cause an ignition arc.
Disconnecting either plug wire disrupts that careful balance and the engine
cannot run. Now, if you connect the disconnected wire to ground, the other
cylinder CAN still fire and the engine run POORLY. But when you pull that
wire off, the engine will die immediately; it may or may not restart on
that single cylinder.

To check for spark at a removed spark plug, or a pulled plug wire, it's
always necessary to securely ground the other plug wire. Even then, the
Onan's spark will be very faint. One more good reason to install the
Pertronix upgrade pioneered by Lawrence Gaskins.

Ken H.

On Thu, Jun 7, 2018 at 7:16 PM Will wrote:

> Running on half the engine? Pull one plug wire, see if it dies vs no change
> at all.
>
> On Thu, Jun 7, 2018, 3:12 PM Deb McWade wrote:
>
>> James Hupy wrote on Thu, 07 June 2018 10:51
>>> Rattle when running could be the engine mount cushions. When they fail,
>> the
>>> starter bracket rattles against the frame. Not too difficult to change.
>>> Applied has them in stock.
>>
>>
>> Thanks James. Sounds more like a rubbing sound than a rattle, but I will
>> take a look at the mounts and also check the starter bracket. Hopefully
>> something simple like that. But I don't hold my breath on anything
>> anymore ;)
>> --
>> Deb McWade
>> Logan Lake, BC, CAN
>> "Li'l Sister"
>> '77 Kingsley, 403, EBL EFI;
>> TZE167V101404
>> It's Bigger on the Inside!
>>
>>
>> _______________________________________________
>> 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
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

Report message to a moderator

Re: Noisy Onan [message #333209 is a reply to message #333188]

Thu, 07 June 2018 19:25

Deb

Messages: 349
Registered: October 2016
Location: Logan Lake, BC

Karma: 2

Senior Member

rjw wrote on Thu, 07 June 2018 15:07

Deb wrote on Thu, 07 June 2018 13:34
Got the Onan running, but not well I think. Sat for 4 days after getting it back, took about 15 seconds to start (sounded like wasn't getting fuel; fine on re-start). Since I have never had it running, and haven't heard another, I can't be certain, but I don't think it should sound like this....https://www.screencast.com/t/3dRknmXzB

Oil, filter, etc all good, new fuel filter.

Of course louder than is coming up here, like a metal fan striking the housing, but more intense. Any ideas about what I'm looking at here before I take the next step? Or you tell me what that should be

Thanks for your insight... I have none naturally. Deb

My Onan developed a sound just like that on my last trip. Turned out the flywheel was loose and rubbing against the front of the Onan. Made a sound just like your audio file. All I had to do was tightened the bolt back to spec and the rattle went away.

Sounds like a definite possibility! Wouldn't it be nice if it turns out to be that simple?! What is the spec torque on the nut BTW? She's parked tomorrow (have to head to work for the last day before I dedicate myself to getting everything set to go). But the weekend, Tues & Wed are GMC days! Will be pulling the drawer and going over it - if we have time, maybe even put Gary's pertronix ignition in!!

Deb McWade Logan Lake, BC, CAN GMC Alumnus It's Bigger on the Inside!

Report message to a moderator

Re: Noisy Onan [message #333213 is a reply to message #333173]

Thu, 07 June 2018 19:56

captjack

Messages: 271
Registered: February 2010
Location: Sebastopol, California

Karma: 1

Senior Member

In addition to Gary's Pertronix ignition mod you might want to consider Jerry Work's propane conversion. My Onan starts and runs so much better with it. You buy it as a kit from US Carburetion.

Jack Christensen - K6ROW, '76 Glenbrook/Clasco - "The Silver Bullet", Sebastopol, CA

Report message to a moderator

Re: Noisy Onan [message #333218 is a reply to message #333213]

Thu, 07 June 2018 21:49

Deb

Messages: 349
Registered: October 2016
Location: Logan Lake, BC

Karma: 2

Senior Member

captjack wrote on Thu, 07 June 2018 17:56

In addition to Gary's Pertronix ignition mod you might want to consider Jerry Work's propane conversion. My Onan starts and runs so much better with it. You buy it as a kit from US Carburetion.

Jerry mentioned that - also on my list. Hoping the noise is just the flywheel and an adjustment will help solve that. I'll know better Saturday... Thanks for the link to the kit!

Deb McWade Logan Lake, BC, CAN GMC Alumnus It's Bigger on the Inside!

Report message to a moderator

Re: Noisy Onan [message #333221 is a reply to message #333209]

Thu, 07 June 2018 22:25

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

Deb wrote on Thu, 07 June 2018 20:25

rjw wrote on Thu, 07 June 2018 15:07
Deb wrote on Thu, 07 June 2018 13:34
Got the Onan running, but not well I think. Sat for 4 days after getting it back, took about 15 seconds to start (sounded like wasn't getting fuel; fine on re-start). Since I have never had it running, and haven't heard another, I can't be certain, but I don't think it should sound like this....https://www.screencast.com/t/3dRknmXzB

Oil, filter, etc all good, new fuel filter.

Of course louder than is coming up here, like a metal fan striking the housing, but more intense. Any ideas about what I'm looking at here before I take the next step? Or you tell me what that should be

Thanks for your insight... I have none naturally. Deb

My Onan developed a sound just like that on my last trip. Turned out the flywheel was loose and rubbing against the front of the Onan. Made a sound just like your audio file. All I had to do was tightened the bolt back to spec and the rattle went away.

Sounds like a definite possibility! Wouldn't it be nice if it turns out to be that simple?! What is the spec torque on the nut BTW? She's parked tomorrow (have to head to work for the last day before I dedicate myself to getting everything set to go). But the weekend, Tues & Wed are GMC days! Will be pulling the drawer and going over it - if we have time, maybe even put Gary's pertronix ignition in!!

According to my Onan "Major Service Manual for NH Power Drawer, 6KW Electric Power Plant for Recreational Vehicles" booklet, the flywheel mounting screw torque is Min of 35 and Max of 40 foot pounds. Too much torque and you run the risk of cracking it.

Report message to a moderator

Previous Topic:	[GMCnet] Noisy Onan
Next Topic:	[GMCnet] CV boot replacement

Goto Forum:

-=] Back to Top [=-

Current Time: Tue Nov 05 23:53:41 CST 2024

Total time taken to generate the page: 0.01320 seconds