Home » Public Forums » GMCnet » removing onan flywheel (fixing oil leaks)
| removing onan flywheel [message #176637] |
Fri, 13 July 2012 15:19  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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When I ran my onan for the trip home the other day. about an hour into the trip, I had stopped to check things to find oil spray on the muffler. this was the longest the onan had run since I have had the motorhome.
I read plenty of posts, and I hope I have it figured out. I am replacing the front seal, the oil filter bracket gasket and the LOP switch.
I just wanted to share my experience, in case anybody out there is trying to do the same.
The job seemed really easy. and I think it is. Tin came off easy to access everything. I did run into a problem removing the flywheel.
a couple posts showed harmonic balance pully puller being used. I destroyed two of them. with zero luck getting the pully to budge.
see picture:
http://3.bp.blogspot.com/-CUiOdnEuJ9c/UAB30XXWEcI/AAAAAAAAQSs/4QHcjuakwzI/s320/broketools.jpg
as you can see, I worked the heck out of them. and this was a process over a couple evenings. I cranked up the tension. and let them sit overnight.
anyway to make this short, I bought a $14.00 timing gear puller from O'reilies autoparts. and it popped it right off. It fit nice, and worked well. I had it off in about 2 minutes using the "timing gear puller" I just had to use 2ea 3/8 in bolts, because the bolts that came with the puller were one size too small.
http://1.bp.blogspot.com/-V-nwZkUm1cY/UAB31tsdTeI/AAAAAAAAQS0/6STstxpy2zU/s320/newpuller.jpg
it is actually has a lifetime warantee, and you can "rent" it. so I could bring it back and get my $14.00 back.
now to figure out how to get the front seal out.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] removing onan flywheel [message #176643 is a reply to message #176640] |
Fri, 13 July 2012 15:54  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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Amen.
and ouch!
Larry Davick
Fremont, California
A Mystery Machine
'76 (ish) Palm Beach
----- Original Message -----
From: "Bruce Hislop" <bruce@perthcomm.com>
To: gmclist@temp.gmcnet.org
Sent: Friday, July 13, 2012 1:42:06 PM
Subject: Re: [GMCnet] removing onan flywheel
Jon,
I'm not sure if you saw a recent posting where someone did not use a torque wrench when he re-installed the flywheel.
He over-torqued the nut and cracked the flywheel!
The correct torque is import to prevent this from happening.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: removing onan flywheel [message #176645 is a reply to message #176637] |
Fri, 13 July 2012 16:07 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Jon,
I recently made a valiant (but seemingly unsuccessful) attempt to stop my Onan from leaking. A few tips:
First; you will need two gaskets for the oil filter adapter. The plate that mounts the engine to the slide is fastened to the engine by the two 5/16" studs that mount the adapter. It requires a gasket on each side, like a sandwich. You can use a 1/2" distributor wrench to get to the nuts.
Second; to get the crank shaft seal out, you will need a slide hammer. Drill a hole in the seal. and thread an appropriate sized screw into the thread, adapt it to the slide hammer (or if the slide hammer has a threaded stud on the end of it, just use that) and apply the slide hammer to it. You will probably pull the screw out of the hole. Drill another one on the opposite side and repeat until the seal comes out. I had to do this 10 or 11 times before the seal came out.
I also removed the oil pan, cleaned up the gasket and reinstalled it using RTV on both sides. Matt says to use RTV on only one side, and if I had read his advice on time, I would have done it that way. Get a proper size copper sealing washer for the plug while you are at it.
All of this did NOT fix my leak completely. I'm not sure, but I think there is a gasket-ed joint between the part (girdle?) that the oil pan bolts to and the cylinder casting. I think that is where my remaining leak is coming from. If you remove the oil pan, check to see if there are bolts above it that you can tighten up to stop that potential leak.
Hopefully someone can clear up that last point for us.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] removing onan flywheel [message #176648 is a reply to message #176645] |
Fri, 13 July 2012 16:58 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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The onan pan has bolts that go through the bottom of the pan, if it is a
cast pan. The engines with the sheet steel oil pans bolt on the same way
that the pan on your 455 does. The only drawback to the cast pan is that
you have to have access to the bottom of the engine. The engines that have
a power drawer are no problem, but the engines that do not pull in and out
on slides have to be removed from the cave to tignten the bolts. A real
pita.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Fri, Jul 13, 2012 at 2:07 PM, Carl Stouffer <carljr3b@yahoo.com> wrote:
>
>
> Jon,
>
> I recently made a valiant (but seemingly unsuccessful) attempt to stop my
> Onan from leaking. A few tips:
>
> First; you will need two gaskets for the oil filter adapter. The plate
> that mounts the engine to the slide is fastened to the engine by the two
> 5/16" studs that mount the adapter. It requires a gasket on each side,
> like a sandwich. You can use a 1/2" distributor wrench to get to the nuts.
>
> Second; to get the crank shaft seal out, you will need a slide hammer.
> Drill a hole in the seal. and thread an appropriate sized screw into the
> thread, adapt it to the slide hammer (or if the slide hammer has a threaded
> stud on the end of it, just use that) and apply the slide hammer to it.
> You will probably pull the screw out of the hole. Drill another one on
> the opposite side and repeat until the seal comes out. I had to do this 10
> or 11 times before the seal came out.
>
> I also removed the oil pan, cleaned up the gasket and reinstalled it using
> RTV on both sides. Matt says to use RTV on only one side, and if I had
> read his advice on time, I would have done it that way. Get a proper size
> copper sealing washer for the plug while you are at it.
>
> All of this did NOT fix my leak completely. I'm not sure, but I think
> there is a gasket-ed joint between the part (girdle?) that the oil pan
> bolts to and the cylinder casting. I think that is where my remaining leak
> is coming from. If you remove the oil pan, check to see if there are bolts
> above it that you can tighten up to stop that potential leak.
>
> Hopefully someone can clear up that last point for us.
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: removing onan flywheel [message #176661 is a reply to message #176659] |
Fri, 13 July 2012 18:52 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Matt,
I DID check the timing cover bolts and they were tight. I put a socket on them and checked them, expecting them to turn a little, but they wouldn't turn, even with a moderate amount of force. I was afraid to use too much. I will pull it out again and see if I can find the other bolts you speak of. I had it running the other day for 20 - 30 minutes, and now have a small oil spot under it on my driveway. I've kind of had it with the thing for now, and will tackle it another day.
Carl
Leaving in the morning for a week long GMC trip to Silver City NM.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] removing Onan flywheel [message #176663 is a reply to message #176661] |
Fri, 13 July 2012 18:58 |
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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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Carl,
Hmmmmm; sounds like Onans are like Harleys; they don't leak, they just mark their spot! ;-)
Regards,
Rob M.
-----Original Message-----
From: Carl Stouffer
Matt,
I DID check the timing cover bolts and they were tight. I put a socket on them and checked them, expecting them to turn a little,
but they wouldn't turn, even with a moderate amount of force. I was afraid to use too much. I will pull it out again and see if I
can find the other bolts you speak of. I had it running the other day for 20 - 30 minutes, and now have a small oil spot under it
on my driveway. I've kind of had it with the thing for now, and will tackle it another day.
Carl
Leaving in the morning for a week long GMC trip to Silver City NM.
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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: removing onan flywheel [message #176673 is a reply to message #176637] |
Fri, 13 July 2012 21:03 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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I can deal with a little oil leak. I have my VW. but what I had was a fire waiting to happen. fan spraying it all over the muffler.
I am not touching the oil pan on this time around. the leak I do not think is coming from there. it is coming from the fan area for sure. fan is scattering oil everywhere. I do have the two gaskets. I drilled out the front seal, and I have some hooks that i was able to pull the thing out with. did not use a slide hammer. I got my shop vac in there really good to make sure i had all the metal pieces out. and ran a magnet around before installing the new seal.
I am glad I checked the net before I finished. actually it rained for a bit, so I came in... I have not checked the timing cover. I will do that before I put the flywheel back on(with torque wrench).
I am taking the time to clean the daylights out of everything in that area. so if it does still leak, maybe I can pin point it down. the oil filter gaskets were pretty poor looking. so I am hoping that is where the leak was. it was a mess in there, so no telling what might have been leaking.
thanks.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] removing Onan flywheel [message #176674 is a reply to message #176663] |
Fri, 13 July 2012 21:23 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| Robert Mueller wrote on Fri, 13 July 2012 16:58 |
Carl,
Hmmmmm; sounds like Onans are like Harleys; they don't leak, they just mark their spot! 
Regards,
Rob M.
-----Original Message-----
From: Carl Stouffer
Matt,
I DID check the timing cover bolts and they were tight. I put a socket on them and checked them, expecting them to turn a little,
but they wouldn't turn, even with a moderate amount of force. I was afraid to use too much. I will pull it out again and see if I
can find the other bolts you speak of. I had it running the other day for 20 - 30 minutes, and now have a small oil spot under it
on my driveway. I've kind of had it with the thing for now, and will tackle it another day.
Carl
Leaving in the morning for a week long GMC trip to Silver City NM.
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I guess so, Rob. I should be used to it by now. I've had a 1953 Willys Jeep for over 40 years and they leak like... well... a Harley  It's parked over a big drip pan.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: removing onan flywheel [message #176689 is a reply to message #176661] |
Sat, 14 July 2012 08:51 |
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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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| Carl S. wrote on Fri, 13 July 2012 19:52 |
Matt,
I DID check the timing cover bolts and they were tight. I put a socket on them and checked them, expecting them to turn a little, but they wouldn't turn, even with a moderate amount of force. I was afraid to use too much. I will pull it out again and see if I can find the other bolts you speak of. I had it running the other day for 20 - 30 minutes, and now have a small oil spot under it on my driveway. I've kind of had it with the thing for now, and will tackle it another day.
Carl
Leaving in the morning for a week long GMC trip to Silver City NM.
|
Carl,
I guess you got that real right.
You have stopped all the leaks you had. When I found the oil filter adapter loose and leaking, I redid it and it took a few more running hours for oil to stop dripping of the Onan even though I did my best to clean all off all the oil I could see.
Mine did have several loose screws in the timing cover and some other places, but the oil filter adapter was the only gasket I had to replace. I replace the LOP switch (that was also leaking) at the same time.
Safe Travel
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: removing onan flywheel [message #176855 is a reply to message #176637] |
Sun, 15 July 2012 20:42 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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Well. Onan is back together. running. and so far, after about a 15 minute run. the major leak seems to be gone.
I did break off two bolts on the tin, going into the head. so I have to drill those out/retap and get that piece back on. will do that tomorrow or tuesday.
real test will be back on the road running with A/C on.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] removing onan flywheel [message #176882 is a reply to message #176637] |
Mon, 16 July 2012 04:44 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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wow very impressive, both the destruction, and the solution.
that tool has been very useful over the years.
http://gmcmotorhome.info/figs/pulltire.jpg
might want to consider putting your pictures on the gmc photo site
thanks for the info
gene
On Fri, Jul 13, 2012 at 1:19 PM, Jon Roche <lqqkatjon@gmail.com> wrote:
>
>
> When I ran my onan for the trip home the other day. about an hour into
> the trip, I had stopped to check things to find oil spray on the muffler.
> this was the longest the onan had run since I have had the motorhome.
>
> I read plenty of posts, and I hope I have it figured out. I am replacing
> the front seal, the oil filter bracket gasket and the LOP switch.
>
> I just wanted to share my experience, in case anybody out there is trying
> to do the same.
>
> The job seemed really easy. and I think it is. Tin came off easy to
> access everything. I did run into a problem removing the flywheel.
>
> a couple posts showed harmonic balance pully puller being used. I
> destroyed two of them. with zero luck getting the pully to budge.
>
> see picture:
>
> http://3.bp.blogspot.com/-CUiOdnEuJ9c/UAB30XXWEcI/AAAAAAAAQSs/4QHcjuakwzI/s320/broketools.jpg
>
> as you can see, I worked the heck out of them. and this was a process
> over a couple evenings. I cranked up the tension. and let them sit
> overnight.
>
> anyway to make this short, I bought a $14.00 timing gear puller from
> O'reilies autoparts. and it popped it right off. It fit nice, and worked
> well. I had it off in about 2 minutes using the "timing gear puller" I
> just had to use 2ea 3/8 in bolts, because the bolts that came with the
> puller were one size too small.
>
>
> http://1.bp.blogspot.com/-V-nwZkUm1cY/UAB31tsdTeI/AAAAAAAAQS0/6STstxpy2zU/s320/newpuller.jpg
>
> it is actually has a lifetime warantee, and you can "rent" it. so I
> could bring it back and get my $14.00 back.
>
> now to figure out how to get the front seal out.
>
>
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
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] removing Onan flywheel [message #177218 is a reply to message #176663] |
Wed, 18 July 2012 17:27 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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My alltime fave scooter was an old BSA Victor Special 441 thumper. If there wasn't a puddle or two under the thing, it was out of oil. All three grades. It wanted 90 weight in the transmission, 30 weight in the primary chain/clutch case, and 40 or 50 depending outside temp in the oil tank - dry sump system. All of them leaked. My GMC is bone dry by com[arison. And has almost as much low end torque.
--johnny
'76 23' transmode norris
'76 palm beach
From: Rob Mueller <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Sent: Friday, July 13, 2012 7:58 PM
Subject: Re: [GMCnet] removing Onan flywheel
Carl,
Hmmmmm; sounds like Onans are like Harleys; they don't leak, they just mark their spot! ;-)
Regards,
Rob M.
-----Original Message-----
From: Carl Stouffer
Matt,
I DID check the timing cover bolts and they were tight. I put a socket on them and checked them, expecting them to turn a little,
but they wouldn't turn, even with a moderate amount of force. I was afraid to use too much. I will pull it out again and see if I
can find the other bolts you speak of. I had it running the other day for 20 - 30 minutes, and now have a small oil spot under it
on my driveway. I've kind of had it with the thing for now, and will tackle it another day.
Carl
Leaving in the morning for a week long GMC trip to Silver City NM.
_______________________________________________
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Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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