Home » Public Forums » GMCnet » Re: [GMCnet] So, about removing the Onan heads and looking for carbon...
| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192719] |
Mon, 10 December 2012 10:16  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Clean the carbon with a wire brush, or a scraper. Alls you need to do is look out for the sealing surface where the head gasket goes and don't dig into the metal there. If there's carbon on the heads and piston tops it will be obvious. wire brush it off. If you have a steady hand, use a wire brush in a drill, it's easier. Use a hand brush to clear the crud outa the fins. There are solvents, but they're nasty stuff to mess with and the brush works well. A carb rebuild kit is a Good Idea after all these years, it will have gaskets and seals which haven't hardened and thus still seal.
--johnny
'76 23' transmode norris
'76 palm beach
From: Robin Hood <loxley@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, December 10, 2012 8:11 AM
Subject: [GMCnet] So, about removing the Onan heads and looking for carbon...
What am I looking for, exactly, and what do I do with it when I find it?
I need to remove the Onan cover from over the heads and clean the cooling fins.
I need to take off the cylinder heads and "look for carbon" but I've
never done this before so I don't really know what I'm looking for.
Surely somebody has documented the process on the GMC photo site?
If there's any carbon, I have to clean it away. Whether this requires
chemicals or just a damp rag I don't know. Neither do i know what it's
even necessary in the first place... but I do know I don't want to get
back into my Onan once I've got it in the coach.
Need a carb kit from JimK just to be on the safe side. My chemdip
prolly ate the gaskets in the needle/seat (I didn't know that stuff
was removable),
--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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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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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192728 is a reply to message #192719] |
Mon, 10 December 2012 15:59  |
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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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Robin,
You can clean the carbon (black / brown stuff) off the heads and the top of the piston with Easy Off Oven Cleaner.
The heads are easy:
1) Put several layers of news paper down on your garage floor
2) Lay the heads on the newspaper with the carbon facing up
3) Spray the heads with Easy Off
4) Let it soak in and loosen the carbon
5) Scrap / wire brush the carbon stuff off
6) Spray them again if it all didn't come off
The pistons are a bit tricky
1) Turn over the Onan until one of the pistons is all the way up in the cylinder
2) Spray it with Easy Off
3) Let it soak in and loosen the carbon
4) Scrap / wire brush the carbon off
5) Spray them again if it all didn't come off
6) When all the carbon is off the piston take a can of WD-40 and spray it in the space between the piston and cylinder start at
12:00 and go counter clockwise down to 6:00. Repeat going from 12:00 to 6:00 clockwise. Do this several time to get all the Easy Off
out between the piston and cylinder.
7) Rotate the Onan enough to lower the piston about 1/2 inch in the cylinder and wipe the bore out
8) Return the piston to its original position and repeat the WD-40 spray.
I used this procedure on Harleys a lot and never had any problems.
Regards,
Rob M.
From: Robin Hood
What am I looking for, exactly, and what do I do with it when I find it?
I need to remove the Onan cover from over the heads and clean the cooling fins.
I need to take off the cylinder heads and "look for carbon" but I've
never done this before so I don't really know what I'm looking for.
Surely somebody has documented the process on the GMC photo site?
If there's any carbon, I have to clean it away. Whether this requires
chemicals or just a damp rag I don't know. Neither do i know what it's
even necessary in the first place... but I do know I don't want to get
back into my Onan once I've got it in the coach.
Need a carb kit from JimK just to be on the safe side. My chemdip
prolly ate the gaskets in the needle/seat (I didn't know that stuff
was removable),
--
Robin
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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] So, about removing the Onan heads and looking for carbon... [message #192738 is a reply to message #192728] |
Mon, 10 December 2012 19:49 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Senior Member |
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Is there a trick to getting the cylinder head off once the 10 bolts
and washers and nuts is accomplished? I can't seem to get it to budge.
Also, the left side cylinder head cooling fins are COVERED in oil.
http://youtu.be/CeExXjNEPUQ
On Mon, Dec 10, 2012 at 3:59 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Robin,
>
> You can clean the carbon (black / brown stuff) off the heads and the top of the piston with Easy Off Oven Cleaner.
>
> The heads are easy:
>
> 1) Put several layers of news paper down on your garage floor
> 2) Lay the heads on the newspaper with the carbon facing up
> 3) Spray the heads with Easy Off
> 4) Let it soak in and loosen the carbon
> 5) Scrap / wire brush the carbon stuff off
> 6) Spray them again if it all didn't come off
>
> The pistons are a bit tricky
>
> 1) Turn over the Onan until one of the pistons is all the way up in the cylinder
> 2) Spray it with Easy Off
> 3) Let it soak in and loosen the carbon
> 4) Scrap / wire brush the carbon off
> 5) Spray them again if it all didn't come off
> 6) When all the carbon is off the piston take a can of WD-40 and spray it in the space between the piston and cylinder start at
> 12:00 and go counter clockwise down to 6:00. Repeat going from 12:00 to 6:00 clockwise. Do this several time to get all the Easy Off
> out between the piston and cylinder.
> 7) Rotate the Onan enough to lower the piston about 1/2 inch in the cylinder and wipe the bore out
> 8) Return the piston to its original position and repeat the WD-40 spray.
>
> I used this procedure on Harleys a lot and never had any problems.
>
> Regards,
> Rob M.
>
> From: Robin Hood
>
> What am I looking for, exactly, and what do I do with it when I find it?
>
> I need to remove the Onan cover from over the heads and clean the cooling fins.
> I need to take off the cylinder heads and "look for carbon" but I've
> never done this before so I don't really know what I'm looking for.
> Surely somebody has documented the process on the GMC photo site?
> If there's any carbon, I have to clean it away. Whether this requires
> chemicals or just a damp rag I don't know. Neither do i know what it's
> even necessary in the first place... but I do know I don't want to get
> back into my Onan once I've got it in the coach.
> Need a carb kit from JimK just to be on the safe side. My chemdip
> prolly ate the gaskets in the needle/seat (I didn't know that stuff
> was removable),
>
> --
> Robin
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
_______________________________________________
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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192740 is a reply to message #192738] |
Mon, 10 December 2012 20:28 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Robin,
I'm going to suggest the following, HOWEVER, before you do it see what the general consensus is about the idea.
1) Screw four bolts back into the head at each "corner" leaving them about 1/8" away from the head.
2) Put the spark plug back into the head on that side,
3) Disconnect the leads from both spark plugs.
4) Hit the start button.
5) The compression should separate the head from the block.
Regards,
Rob M.
-----Original Message-----
From: Robin Hood
Is there a trick to getting the cylinder head off once the 10 bolts
and washers and nuts is accomplished? I can't seem to get it to budge.
Also, the left side cylinder head cooling fins are COVERED in oil.
http://youtu.be/CeExXjNEPUQ
On Mon, Dec 10, 2012 at 3:59 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Robin,
>
> You can clean the carbon (black / brown stuff) off the heads and the top of the piston with Easy Off Oven Cleaner.
>
> The heads are easy:
>
> 1) Put several layers of news paper down on your garage floor
> 2) Lay the heads on the newspaper with the carbon facing up
> 3) Spray the heads with Easy Off
> 4) Let it soak in and loosen the carbon
> 5) Scrap / wire brush the carbon stuff off
> 6) Spray them again if it all didn't come off
>
> The pistons are a bit tricky
>
> 1) Turn over the Onan until one of the pistons is all the way up in the cylinder
> 2) Spray it with Easy Off
> 3) Let it soak in and loosen the carbon
> 4) Scrap / wire brush the carbon off
> 5) Spray them again if it all didn't come off
> 6) When all the carbon is off the piston take a can of WD-40 and spray it in the space between the piston and cylinder start at
> 12:00 and go counter clockwise down to 6:00. Repeat going from 12:00 to 6:00 clockwise. Do this several time to get all the Easy
Off
> out between the piston and cylinder.
> 7) Rotate the Onan enough to lower the piston about 1/2 inch in the cylinder and wipe the bore out
> 8) Return the piston to its original position and repeat the WD-40 spray.
>
> I used this procedure on Harleys a lot and never had any problems.
>
> Regards,
> Rob M.
>
> From: Robin Hood
>
> What am I looking for, exactly, and what do I do with it when I find it?
>
> I need to remove the Onan cover from over the heads and clean the cooling fins.
> I need to take off the cylinder heads and "look for carbon" but I've
> never done this before so I don't really know what I'm looking for.
> Surely somebody has documented the process on the GMC photo site?
> If there's any carbon, I have to clean it away. Whether this requires
> chemicals or just a damp rag I don't know. Neither do i know what it's
> even necessary in the first place... but I do know I don't want to get
> back into my Onan once I've got it in the coach.
> Need a carb kit from JimK just to be on the safe side. My chemdip
> prolly ate the gaskets in the needle/seat (I didn't know that stuff
> was removable),
>
> --
> Robin
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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] So, about removing the Onan heads and looking for carbon... [message #192783 is a reply to message #192738] |
Wed, 12 December 2012 07:09 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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A gentle tap with a soft hammer also works. Just make sure all the bolts
are removed. Once the bolts are out, it's usually varnish that's making
the seal. As for the oil, once you remove the oil filter, you will see an
adapter between it and the engine. The gasket between the engine and
adaptor is usually the culprit. I tried a replacement, it leaked. I made
my own and as far as I know, it has never leaked.
Is there a trick to getting the cylinder head off once the 10 bolts
> and washers and nuts is accomplished? I can't seem to get it to budge.
> Also, the left side cylinder head cooling fins are COVERED in oil.
>
>
--
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