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 #192742] |
Mon, 10 December 2012 20:30  |
Marcus McGee
Messages: 112
Registered: March 2004
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Worked for me when I did it that way.
Marcus
----- Original Message -----
From: "Rob Mueller" <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Date: Mon, 10 Dec 2012 21:27 -0500
Subject: Re: [GMCnet] So, about removing the Onan heads and looking for carbon...
> 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
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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192750 is a reply to message #192742] |
Tue, 11 December 2012 20:11  |
Robin Hood
Messages: 1078
Registered: April 2011
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Well, that didn't work. Any other ideas? I left the spark plug in, and
cranked, and it didn't come loose. All 8 nuts and two bolts, with all
washers, have been removed. WHat's holding this thing on?
On Mon, Dec 10, 2012 at 8:30 PM, crsalert@frontiernet.net
<crsalert@frontiernet.net> wrote:
> Worked for me when I did it that way.
>
> Marcus
>
> ----- Original Message -----
> From: "Rob Mueller" <robmueller@iinet.net.au>
> To: gmclist@temp.gmcnet.org
> Date: Mon, 10 Dec 2012 21:27 -0500
> Subject: Re: [GMCnet] So, about removing the Onan heads and looking for carbon...
>
>> 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.
>>
>>
--
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 #192755 is a reply to message #192742] |
Tue, 11 December 2012 22:12 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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Robin,
On mine, the two bolts were actually studs with nuts on them, and the studs stayed in the block. The bottom one was seriously corroded to the cylinder head. I was able to put two nuts on it, tighten them very tight against them and work it back and forth using two wrenches to keep the nuts tight to each other while wiggling the stud back and forth. Liberal Kroil application seemed to help Once I got it to turn semi-freely I was able to work the head off the stud.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192760 is a reply to message #192750] |
Wed, 12 December 2012 00:03 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Robin,
Well that's an AW S#!T!
How about a picture of the head; the Onan NOT yours! ;-)
Regards,
Rob M.
-----Original Message-----
From: Robin Hood
Well, that didn't work. Any other ideas? I left the spark plug in, and
cranked, and it didn't come loose. All 8 nuts and two bolts, with all
washers, have been removed. WHat's holding this thing on?
Robin
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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] So, about removing the Onan heads and looking for carbon... [message #192768 is a reply to message #192765] |
Wed, 12 December 2012 09:46 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Robin,
Some person that previously worked on the engine may have use an adhesive on the gaskets. It doesn't take much, or you could have the rusty stud as Craig suggested, but, want a simple clean and fun thing to try?
Get an length of small line. Take off the flywheel cover. Roll the engine back a quarter turn from the timing mark. Take out both spark plugs and feed in a couple of feet of small line into one side only. Leave the tail out. (Just don't bother cutting the line - it will be clean and can still be used.) Roll the engine up to compression. It should not be able to do over the top. - Good
Put a couple of the nuts back on so the head doesn't fall on the floor and get hurt.
Now, Roll the engine backwards until it hits the rope from the other side.
Ready?
Grab the flywheel and give it a good hard spin. When the piston hits the ball of line, it will should break the head loose without any prying or hammering on castings.
Fun? Now you can do the other side.
Oh, and by left side, do you mean the oil filter side? If yes, it is either the filter adapter or the LOP switch that is leaking. Do and will not be a big issue while the machine is out of the coach.
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] So, about removing the Onan heads and looking for carbon... [message #192784 is a reply to message #192760] |
Wed, 12 December 2012 07:12 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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I'm at work and cant post to GMCPhotos from here. I was able to upload
a photo to my Facebook page... If anyone just can't wait to see a
picture of a left hand Onan NH6kw cylinder head, feel free to send me
a friend request. Otherwise, I'll upload it when I get home, and maybe
shoot a short video.
Actually, i shot one last night. I was convinced that cranking the
engine to pop loose the cylinder head would make for a very
interesting video. I even enlisted the assistance of my lovely wife to
be my Igor ("Igor! Pull The Switch!")
Alas, nothing happened. The Onan just clicked, or maybe clacked, and
then did nothing. I about had a hissy fit I was so pissed. I was
convinced that somehow, I had done something and nuked the control
board or something else horrible (that is, electrical/electronic and
hard to diagnose) had happened.
Turned out to just be a low battery. An hour or twoon the charger at
10 amps and it turned over just fine. I just didn't pop loose the
cylinder head is all. :(
On Wed, Dec 12, 2012 at 12:03 AM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Robin,
>
> Well that's an AW S#!T!
>
> How about a picture of the head; the Onan NOT yours! ;-)
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Robin Hood
>
> Well, that didn't work. Any other ideas? I left the spark plug in, and
> cranked, and it didn't come loose. All 8 nuts and two bolts, with all
> washers, have been removed. WHat's holding this thing on?
>
> 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 #192785 is a reply to message #192784] |
Wed, 12 December 2012 07:24 |
Robin Hood
Messages: 1078
Registered: April 2011
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About those "studs"... At the moment, to the best of my understanding
and belief, there were two actual bolts (located in the bottommost two
holes) and eight "studs" with washers and nuts on them in the
remaining holes that collectively hold the cylinder head on. To the
best of my understanding and belief, those studs are part of the
engine block, and are not mechanically connected to the cylinder head
(that is, they're not threaded through the cylinder head) other than
the washers and nuts (currently removed). It would seem to me that the
the cylinder head should seperate from the block and come straight
off.
Something is sticking the cylinder head to the block. They only meet
at the gasket and those studs, so I guess that's where the sticking
point is? Perhaps some sort of penetrating lubricant/oil/degreaser
something... PB Blaster perhaps should be sprayed liberally all over
the place?
The hammer idea is a good one, too. :)
--
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 #192847 is a reply to message #192790] |
Wed, 12 December 2012 23:09 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Do not put too much rope in it. You want the piston to hit the top and the rope just Before Top Dead Center. Stuff a little in and try it. Add a little more only if necessary. If it hit too soon you can bend a still open valve. Also if you can identify the compression stroke then do it on the compression stroke since both valves are closed during that time.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192853 is a reply to message #192847] |
Thu, 13 December 2012 06:53 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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I'm guessing the compression stroke will be the one where the spark
plug hole leaks the most air (since the intake and exhaust valves will
both be closed).
I was bad yesterday and blew my diet by drinking two 20oz cokes and
eating the workplace cafeteria's alleged beef strogonoff. In penance,
i climbed 110 stories (one World Trade Center's worth) on one of those
stair climber dealies at the gym, and was in no shape to mess with the
Onan last night.
I did manage to hose down the various bolts and studs and whatnot with
PB Blaster. I did the intake and exhaust manifolds, as well as the
flywheel cover, just for good measure. I reckon most of that stuff is
coming off eventually anyway. I'd kind of like to get the intake and
exhaust manifolds powdercoated. Probably the cylinder heads, too. I
can do that, right?
I'll hose everything down with PB Blaster again tonight, and let it
soak in even further, and see if I can pull off the cylinder heads
this weekend before I try that rope trick.
On Wed, Dec 12, 2012 at 11:09 PM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> Do not put too much rope in it. You want the piston to hit the top and the rope just Before Top Dead Center. Stuff a little in and try it. Add a little more only if necessary. If it hit too soon you can bend a still open valve. Also if you can identify the compression stroke then do it on the compression stroke since both valves are closed during that time.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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--
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 #192856 is a reply to message #192853] |
Thu, 13 December 2012 07:35 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Robin,
Here's an animation of a Otto Cycle engine aka four stroke. Yes Otto was a Kraut! Naturlich! ;-)
http://www.animatedengines.com/otto.html
Scroll down and each of the four strokes is explained.
To put it in the vernacular prettying up the Onan is like putting perfume on a pig. In fact a pig that hides in an enclosed pen at
that!
Call your local Onan dealer:
CUMMINS MID-SOUTH, LLC (2462)
325 New Highway 49 S
Richland, MISSISSIPPI 39208
Phone: (601) 932-7016
Buy a can or two of the "Official" Onan green (?) paint.
Don't bother to paint the exhaust manifold as the paint will burn off in a heartbeat.
Regards,
Rob M.
-----Original Message-----
From: Robin Hood
I'm guessing the compression stroke will be the one where the spark
plug hole leaks the most air (since the intake and exhaust valves will
both be closed).
I was bad yesterday and blew my diet by drinking two 20oz cokes and
eating the workplace cafeteria's alleged beef strogonoff. In penance,
i climbed 110 stories (one World Trade Center's worth) on one of those
stair climber dealies at the gym, and was in no shape to mess with the
Onan last night.
I did manage to hose down the various bolts and studs and whatnot with
PB Blaster. I did the intake and exhaust manifolds, as well as the
flywheel cover, just for good measure. I reckon most of that stuff is
coming off eventually anyway. I'd kind of like to get the intake and
exhaust manifolds powdercoated. Probably the cylinder heads, too. I
can do that, right?
I'll hose everything down with PB Blaster again tonight, and let it
soak in even further, and see if I can pull off the cylinder heads
this weekend before I try that rope trick.
Robin
_______________________________________________
GMCnet mailing list
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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] So, about removing the Onan heads and looking for carbon... [message #192858 is a reply to message #192856] |
Thu, 13 December 2012 07:39 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Senior Member |
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Don't they have some sort of high tech coatings these days for high
temperature parts? I reeeeeealy dislike rust. When i changed my
Catalina's front drum brakes to discs, I had the spindles and steering
arms and control arms and related parts powdercoated a glossy black.
It wasn't terribly expensive and it looked sharp, although the parts
will likely never be seen.
And I want any future oil leaks (my clinder heads are COVERED in the
stuff) to be glaringly obvious. :)
On Thu, Dec 13, 2012 at 7:36 AM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Robin,
>
> Here's an animation of a Otto Cycle engine aka four stroke. Yes Otto was a Kraut! Naturlich! ;-)
>
> http://www.animatedengines.com/otto.html
>
> Scroll down and each of the four strokes is explained.
>
> To put it in the vernacular prettying up the Onan is like putting perfume on a pig. In fact a pig that hides in an enclosed pen at
> that!
>
> Call your local Onan dealer:
>
> CUMMINS MID-SOUTH, LLC (2462)
> 325 New Highway 49 S
> Richland, MISSISSIPPI 39208
> Phone: (601) 932-7016
>
> Buy a can or two of the "Official" Onan green (?) paint.
>
> Don't bother to paint the exhaust manifold as the paint will burn off in a heartbeat.
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Robin Hood
>
> I'm guessing the compression stroke will be the one where the spark
> plug hole leaks the most air (since the intake and exhaust valves will
> both be closed).
>
> I was bad yesterday and blew my diet by drinking two 20oz cokes and
> eating the workplace cafeteria's alleged beef strogonoff. In penance,
> i climbed 110 stories (one World Trade Center's worth) on one of those
> stair climber dealies at the gym, and was in no shape to mess with the
> Onan last night.
>
> I did manage to hose down the various bolts and studs and whatnot with
> PB Blaster. I did the intake and exhaust manifolds, as well as the
> flywheel cover, just for good measure. I reckon most of that stuff is
> coming off eventually anyway. I'd kind of like to get the intake and
> exhaust manifolds powdercoated. Probably the cylinder heads, too. I
> can do that, right?
>
> I'll hose everything down with PB Blaster again tonight, and let it
> soak in even further, and see if I can pull off the cylinder heads
> this weekend before I try that rope trick.
>
> 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 #192860 is a reply to message #192858] |
Thu, 13 December 2012 08:00 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Robin,
Sure they do; Google Hi-temp exhaust coatings, let us know how much they want to coat the exhaust manifold.
The reason I suggested calling Onan is I would be surprised if powder coaters would be able to match the color of the Onan and I
reckon a multi green toned Onan will look weird.
Regards,
Rob M.
-----Original Message-----
From: Robin Hood
Don't they have some sort of high tech coatings these days for high
temperature parts? I reeeeeealy dislike rust. When i changed my
Catalina's front drum brakes to discs, I had the spindles and steering
arms and control arms and related parts powdercoated a glossy black.
It wasn't terribly expensive and it looked sharp, although the parts
will likely never be seen.
And I want any future oil leaks (my clinder heads are COVERED in the
stuff) to be glaringly obvious. :)
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 #192861 is a reply to message #192860] |
Thu, 13 December 2012 08:12 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Who actually sees the bloody thing unless
it is hauled out for servicing? BFD!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
*[ ]~~~[][ ][|\
*--OO--[]---O-*
> From: robmueller@iinet.net.au
> To: gmclist@temp.gmcnet.org
> Date: Fri, 14 Dec 2012 01:01:31 +1100
> Subject: Re: [GMCnet] So, about removing the Onan heads and looking for carbon...
>
> Robin,
>
> Sure they do; Google Hi-temp exhaust coatings, let us know how much they want to coat the exhaust manifold.
>
> The reason I suggested calling Onan is I would be surprised if powder coaters would be able to match the color of the Onan and I
> reckon a multi green toned Onan will look weird.
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Robin Hood
>
> Don't they have some sort of high tech coatings these days for high
> temperature parts? I reeeeeealy dislike rust. When i changed my
> Catalina's front drum brakes to discs, I had the spindles and steering
> arms and control arms and related parts powdercoated a glossy black.
> It wasn't terribly expensive and it looked sharp, although the parts
> will likely never be seen.
>
> And I want any future oil leaks (my clinder heads are COVERED in the
> stuff) to be glaringly obvious. :)
>
> Robin
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192870 is a reply to message #192856] |
Thu, 13 December 2012 09:22 |
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 Thu, 13 December 2012 06:35 |
Robin,
To put it in the vernacular prettying up the Onan is like putting perfume on a pig. In fact a pig that hides in an enclosed pen at
that!
Call your local Onan dealer:
CUMMINS MID-SOUTH, LLC (2462)
325 New Highway 49 S
Richland, MISSISSIPPI 39208
Phone: (601) 932-7016
Buy a can or two of the "Official" Onan green (?) paint.
Don't bother to paint the exhaust manifold as the paint will burn off in a heartbeat.
Regards,
Rob M.
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I agree with Rob on this. However, that didn't stop me from trying to 'pretty up' my Onan a little. I went over the intake manifold with a wire wheel and took the paint off the aluminum. No need to paint it. It looks good that way. I also brushed down the exhaust manifold and painted it with VHT header paint. I did the same with the exhaust manifolds on the 455, and both still look good. I'm not sure it would be a good idea to coat the heads with anything. I recognize they were painted green from the factory, but I think the bare aluminum would dissipate heat better
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] So, about removing the Onan heads and looking for carbon... [message #192871 is a reply to message #192870] |
Thu, 13 December 2012 09:41 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Robin, if you are thinking of painting the heads, I use a high heat flat
black "shake n shoot" paint like derusto or krylon. Gordon Jennings from
Cycle magazine did a comparison test of coatings on heat dissapation.
Turned out that flat black transferred more heat than cast aluminum or any
gloss coating including powder coat. Granted the testing was before the
invention of Vht coatings, which make some wild ass claims about
themselves. Some of the ceramic header coatings actually serve to contain
the exhaust heat within the tubes. Jwik.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Dec 13, 2012 7:22 AM, "Carl Stouffer" <carljr3b@yahoo.com> wrote:
>
>
> Robert Mueller wrote on Thu, 13 December 2012 06:35
> > Robin,
> >
> >
> >
> > To put it in the vernacular prettying up the Onan is like putting
> perfume on a pig. In fact a pig that hides in an enclosed pen at
> > that!
> >
> > Call your local Onan dealer:
> >
> > CUMMINS MID-SOUTH, LLC (2462)
> > 325 New Highway 49 S
> > Richland, MISSISSIPPI 39208
> > Phone: (601) 932-7016
> >
> > Buy a can or two of the "Official" Onan green (?) paint.
> >
> > Don't bother to paint the exhaust manifold as the paint will burn off in
> a heartbeat.
> >
> > Regards,
> > Rob M.
>
>
>
> I agree with Rob on this. However, that didn't stop me from trying to
> 'pretty up' my Onan a little. I went over the intake manifold with a wire
> wheel and took the paint off the aluminum. No need to paint it. It looks
> good that way. I also brushed down the exhaust manifold and painted it
> with VHT header paint. I did the same with the exhaust manifolds on the
> 455, and both still look good. I'm not sure it would be a good idea to
> coat the heads with anything. I recognize they were painted green from the
> factory, but I think the bare aluminum would dissipate heat better
> --
> 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: [GMCnet] So, about removing the Onan heads and looking for carbon... [message #192873 is a reply to message #192871] |
Thu, 13 December 2012 09:50 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Senior Member |
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Hmm. Maybe having a place bead blast the cylinder heads may be the
best thing after all. I'd hate to choose a paint that acted as an
insulator. I still want to find something to pain the exhaust manifold
with, though. I've seen photos of black exhaust manifolds, and I like
the look. And stainless mufflers too. :)
On Thu, Dec 13, 2012 at 9:41 AM, James Hupy <jamesh1296@gmail.com> wrote:
> Robin, if you are thinking of painting the heads, I use a high heat flat
> black "shake n shoot" paint like derusto or krylon. Gordon Jennings from
> Cycle magazine did a comparison test of coatings on heat dissapation.
> Turned out that flat black transferred more heat than cast aluminum or any
> gloss coating including powder coat. Granted the testing was before the
> invention of Vht coatings, which make some wild ass claims about
> themselves. Some of the ceramic header coatings actually serve to contain
> the exhaust heat within the tubes. Jwik.
> Jim Hupy
> Salem, Or
> 78 Gmc Royale 403
> On Dec 13, 2012 7:22 AM, "Carl Stouffer" <carljr3b@yahoo.com> wrote:
>
>>
>>
>> Robert Mueller wrote on Thu, 13 December 2012 06:35
>> > Robin,
>> >
>> >
>> >
>> > To put it in the vernacular prettying up the Onan is like putting
>> perfume on a pig. In fact a pig that hides in an enclosed pen at
>> > that!
>> >
>> > Call your local Onan dealer:
>> >
>> > CUMMINS MID-SOUTH, LLC (2462)
>> > 325 New Highway 49 S
>> > Richland, MISSISSIPPI 39208
>> > Phone: (601) 932-7016
>> >
>> > Buy a can or two of the "Official" Onan green (?) paint.
>> >
>> > Don't bother to paint the exhaust manifold as the paint will burn off in
>> a heartbeat.
>> >
>> > Regards,
>> > Rob M.
>>
>>
>>
>> I agree with Rob on this. However, that didn't stop me from trying to
>> 'pretty up' my Onan a little. I went over the intake manifold with a wire
>> wheel and took the paint off the aluminum. No need to paint it. It looks
>> good that way. I also brushed down the exhaust manifold and painted it
>> with VHT header paint. I did the same with the exhaust manifolds on the
>> 455, and both still look good. I'm not sure it would be a good idea to
>> coat the heads with anything. I recognize they were painted green from the
>> factory, but I think the bare aluminum would dissipate heat better
>> --
>> 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
>>
> _______________________________________________
> 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 #192876 is a reply to message #192873] |
Thu, 13 December 2012 10:51 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Robin, Here's what it looks like with the VHT on the Manifold. You could get the intake bead blasted too. VHT is available at most 'speed shops'.
http://www.gmcmhphotos.com/photos/onan-mount-replacement/p43925-onan-mounts.html
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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