Home » Public Forums » GMCnet » [GMCnet] Excessive oil consumption
| [GMCnet] Excessive oil consumption [message #59907] |
Mon, 12 October 2009 19:11  |
David L Greenberg
Messages: 899
Registered: January 2004
Location: Port St Lucie, FL
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On Mon, 12 Oct 2009 15:54:12 -0500 SR Wright <SWr7505137@aol.com> writes:
>
>
> After reading all the posts about oil consumption , plus the ones
> about the rocker arm cover on the right side of the engine possibly
> being the cause of some of it. But no one ever posted where you
> might get the right one . What vehicle , truck , or did they only
> come on the GMC motor homes . My 1978 Royale has a 455 that was
> balanced & blue printed before I bought it . Has a oil consumption
> problem thats bothers me . I thought that I would give the rocker
> arm cover a try if I could find one .
>
> Sherman
>
Welcome to the Net.
What kind of oil consumption are you seeing?
David Lee Greenberg
Port St Lucie, FL
Dedicated to the Preservation of the Classic GMC Motorhome
http://GMCmhRegistry.com
48 Packard Super Eight
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| Re: [GMCnet] Excessive oil consumption [message #60197 is a reply to message #59907] |
Thu, 15 October 2009 12:21  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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sherman:
I have seen pictures of 2 different but similar valve covers
that are supposed to be the correct valve covers. They both have a metal splash shield that are longer then the car covers.
I believe there are pictures on Gene Fishers web site. However my 76 Glen brook came from the factory with the supposed wrong auto valve covers and my oil consumption is normal. I have seen these different covers on a 69 425 engine so maybe they were used on older cars also. If your pcv hose is wet and dripping oil when you take it loose at the carburetor I would say oil is coming out of the valve cover but if it is not wet but dry I would say it is not the valve cover . Possibly guides or rings?
I hope this helps
Roy
76 x glen brook
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Thu, 15 October 2009 14:39] Report message to a moderator |
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| Re: [GMCnet] Excessive oil consumption [message #60260 is a reply to message #59907] |
Thu, 15 October 2009 22:22 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
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i've thought about this too but you would also have to have a crack between the intake runner and the crossover. from what i've seen, which is limited, the upper part cracks between the secondaries a little bit which should not be a problem at all. some of the race guys actually cut a notch there.
maybe someone has more to say on this.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] Excessive oil consumption [message #60298 is a reply to message #60260] |
Fri, 16 October 2009 08:04 |
Rick Denney
Messages: 430
Registered: January 2004
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fred veenschoten writes...
> i've thought about this too but you would also have to have a crack
> between the intake runner and the crossover. from what i've seen,
> which is limited, the upper part cracks between the secondaries a
> little bit which should not be a problem at all. some of the race guys actually cut a notch there.
The problem is that you may have to flow-bench the intake to know for
sure. But you can have cracks around the choke-tube opening, and I've
seen pictures (I think from Kelvin Dietz) who had a crack extending
along the bottom of the crossover across the whole width of the
crossover. Even that crack might not extend into the intake runner and
cause a vacuum leak. But if you blow through one of the block-off
plates (highly unlikely unless maybe you have a plugged muffler), then
you'll be pumping exhaust into the lifter gallery. Not to mention that
cracks travel.
The crossovers in these manifolds get too hot for two reasons: 1. The
high-power requirements of the GMC create much more heat than in the
passenger-car application, and 2.) old exhaust systems are more likely
to have a plugged muffler, forcing that bank to at least partly
exhaust through the other bank. That the crossover gets exceptionally
hot is a no-brainer--mine was severely eroded on the outside surface,
to about the same degree as the original exhaust manifolds.
It is amazing how much oil is present in that lifter gallery. I had a
vacuum leak between the manifold and the lifter gallery that did not
significantly affect the driveability of the coach (until the plug
fouled) that pulled five quarts of oil through the engine in 200
miles.
If there are no cracks on the bottom of the crossover, then it won't
matter even if vacuum leaks into the crossover. But if the bottom is
cracked (as it was for Kelvin, at least), I would either fill it or
replace it with a manifold from Gary Rockwell.
The Rockwell manifold is expensive, to be sure, when compared to an
Edelbrock. But that's the way it is with very limited-edition custom
products. I doubt Gary stands any chance of making his money back,
even if he doesn't charge for the time he put into the development.
Not everyone will be able to afford it. But it is still a pretty small
expenditure for those who might need a replacement compared with some
of the mods we've been freely discussing for the last few weeks.
Rick "who has several items on the to-do list put off for lack of
discretionary funds" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: [GMCnet] Excessive oil consumption [message #61229 is a reply to message #61201] |
Thu, 22 October 2009 21:20 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
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Is the dipstick calibrated?
Ljdavick at comcast.net
On Oct 22, 2009, at 4:34 PM, SR Wright <SWr7505137@aol.com> wrote:
>
>
> Roy,
> Dont think its the valve guides or rings, motor has less than 10K
> miles on it since PO spent over $5000 on it. He had it balanced &
> blueprinted. Just got back from a trip of 320 mi. round trip , it
> lost about 1 qt. I say it lost it because it
> doesn't smoke , doesn't leak ,it just got lost.
> Thanks ,
> Sherman
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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: [GMCnet] Excessive oil consumption [message #61476 is a reply to message #61260] |
Sat, 24 October 2009 15:42 |
philipswanson
Messages: 282
Registered: January 2004
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Lately, my coach is doing the same thing. No smoke at breather on rocker cover, no smoke out the tailpipe, passes smog, plugs good, no leaks. Still "loses" a quart every 250-300 miles of leadfoot driving. Runs great though with lots of power. My latest theory is that either the Edelbrock intake is cracked underneath somewhere and/or my Edelbrock cast iron block off plugs have erroded allowing the manifold to get hot underneath, and with no turkey tray, lots of oil burning and no outside signs. Leakdown and compression is fine but I think this oil is burning through underneath the intake but slow enough where you can't see it in the exhaust. Motor, 455 has about 30K on it.
[Updated on: Sat, 24 October 2009 15:43] Report message to a moderator |
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| Re: [GMCnet] Excessive oil consumption [message #61479 is a reply to message #61476] |
Sat, 24 October 2009 16:10 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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Phil,
Have you ever seen the photos of Ken Henderson's heads that had the cast
iron plugs in the heads?
Link to the first photo in the series below:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=1303
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Phil Swanson
Sent: Sunday, 25 October 2009 7:42 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Excessive oil consumption
Lately, my coach is doing the same thing. No smoke at breather on rocker
cover, no smoke out the tailpipe, passes smog, plugs good, no leaks. Still
"loses" a quart every 250-300 miles of leadfoot driving. Runs great though
with lots of power. My latest theory is that either the Edelbrock intake is
cracked underneath somewhere and/or my Edelbrock cast iron block off plugs
have erroded allowing the manifold to get hot underneath, and with no
turkey tray, lots of oil burning and no outside signs. Leakdown and
compression is fine but I think this oil is burning through underneath the
intake but slw enough where you can't see it in the exhaust. Motor, 455 has
about 30K on it.
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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] Excessive oil consumption [message #61504 is a reply to message #61479] |
Sat, 24 October 2009 19:59 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Rob
Those plugs will definitely eat up the head. I had the same problem but caught mine in time to save the heads.It doesn't matter if they are a tight fit either. The machine shop I use likes the plugs, they coat them with a high temperature epoxy before inserting them. Might work if you can trust the epoxy won't work loose? I wouldn't trust them though unless they were welded.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Excessive oil consumption [message #61511 is a reply to message #61201] |
Sat, 24 October 2009 20:33 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Sherman
Back in the 70's I built a small block 400 Chevy motor for my camper and a 455 olds for my jet boat. Both of those engines used more oil then they should have. I know the piston clearance was correct on both motors and the rings were too as I was the one putting them together. They both had molly rings on the two top compression rings. I have always felt the machine shop didn't get the proper finish hone on the cylinders which caused me to use more oil then I should have. The Chevy engine used about 350 to 400 miles to a quart. At that time molly rings was something new. My present engine only has a molly ring for a top ring and it doesn't use oil.The camper is long gone but the boat still lives in my garage. For me its easier to just feed it more oil then tear it down hone and re -ring it. I found some oil held up better then others for instance Valvoline at that time caused me to use twice as much oil. Torco, Castol and mobil 1 20/50 or 15/50 were much better. I never noticed the engines smoking.
If you have ruled out an intake problem I would suspect the rings may not have taken a good set??
Roy
76 x glenbrook
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Excessive oil consumption [message #61522 is a reply to message #61201] |
Sat, 24 October 2009 21:47 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
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| vega7677 wrote on Thu, 22 October 2009 16:34 |
Roy,
I say it lost it because it doesn't smoke , doesn't leak ,it just got lost.
Thanks ,
Sherman
|
If you use synthetic oil, it does not smoke like the old oils. Someone said that even if it isn't smoking, it may build up lost of carbon.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Excessive oil consumption [message #61526 is a reply to message #61522] |
Sat, 24 October 2009 23:29 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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| George Beckman wrote on Sat, 24 October 2009 21:47 |
| vega7677 wrote on Thu, 22 October 2009 16:34 |
Roy,
I say it lost it because it doesn't smoke , doesn't leak ,it just got lost.
Thanks ,
Sherman
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If you use synthetic oil, it does not smoke like the old oils. Someone said that even if it isn't smoking, it may build up lost of carbon.
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Believe me the build up from burning synthetic oil is not carbon. It is more like someone poured epoxy in the head and on top of the piston. We had one that our sandblaster could not remove the residue. We literally chiseled and wire brushed the stuff out of the heads, valves, and on top of the pistons. A ridge cutter did get it out of the cylinders. I compare that to how easily the same blaster (with glass beads in it) removed the carbon and excess lead buildup out of my cylinder yesterday.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Excessive oil consumption [message #61635 is a reply to message #61533] |
Sun, 25 October 2009 19:50 |
philipswanson
Messages: 282
Registered: January 2004
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My Edelbrock plugs are welded in. I am pulling the Edelbrock intake tomorrow to have a look. I am operating under the theory that my intake is leaking at the bottom edge inside the valley. In talking with Dick Paterson, this is very common because many of the blocks and heads have been surfaced to the point where the intake is a lousy fit. A thicker gasket like the 404 Mr. Gasket just makes it worse because it raises the manifold even more and just increases the mismatch. Dick no longer uses the thick 404 gasket in his block off kits because they are too thick. After I pull the aluminum manifold, I am going to clean it and install it dry and measure the fit at the top and bottom at each corner, as Dick recommends. Then, I am going to run the small Mondello tray and put in Dicks gaskets. Also going to see what;s going on with the welded in plugs. I have seen the pictures but I need to see mine before I jump to the conclusion that they are doing harm. They do have the holes drilled in them.
Phil Swanson
77GMCPB
[Updated on: Sun, 25 October 2009 19:51] Report message to a moderator |
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