Home » Public Forums » GMCnet » [GMCnet] engine clicking... header leak...
| [GMCnet] engine clicking... header leak... [message #142106] |
Fri, 02 September 2011 12:29  |
Ek_Lektro
Messages: 167
Registered: March 2011
Karma: 2
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Senior Member |
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Need a little advise please:
My '78 403 has had what i'm guessing is a valve clicking noise for the past year or so, coming from the top left of the engine.
Lately its become quite loud after starting up with a cold engine... and of course it dies down a bit after warming up,
but never fully goes away. i know this is pretty common, and probably a sign of eventual need for a valve job.
But recently i discovered a couple possible reasons why its been so much louder lately:
A friend helped me with some work last summer, part of which was changing the spark plugs (but we didn't get to changing the wires at that time since the shop was out of stock...) So when i was finally changing wires last week, i found that one of the spark plugs was really loose, like 2 turns away from falling out. Not sure if it was that loose to begin with, or if i'd been driving it for a whole year like that, but i put in a new plug to be safe and tightened it up.
Was hoping that this might've been the cause for the clicking noise, 'cause at times the click has such a high pitch to it, it almost sounds electrical. But no... the click remained. So i took a hose and used it as a stethoscope to pinpoint the noise, and i found out that i have an air leak between the headers and the manifold. Interestingly the leak is immediately below the particular spark plug that was so incredibly loose. Is this just a coincidence? or did something go out of whack by driving for a year with a loose plug? Anyway, i tried to tighten up the 2 bolts at that part of the header, but apparently not tight enough, 'cause i still have the air leak, and the clicking noise is only slightly dampened. I guess the next step is to try to loosen all of the header bolts, and try to tighten them up in sequence, to see if i can get rid of the leak completely, and hopefully the clicking noise will not be as severe. i don't recall there being any kind of header gasket to
replace, so beyond getting some special heavy-duty 7/16" wrench into those tight spaces, are there are any tricks to solving header leaks?
Thanks in advance for any advice!
Greg
'78 eleganza II
PS: a little history on the coach:
new Thorley headers installed in '98... Re-installed with a rebuilt engine in '02
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| Re: [GMCnet] engine clicking... header leak... [message #142108 is a reply to message #142106] |
Fri, 02 September 2011 12:49  |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Greg,
My 455 has stock manifolds. They have always leaked a little. One side had cracks that had to be welded. I have found replacing the exhaust gaskets with copper gaskets helps a lot. The advice I hear is not to torque the bolts too tight and tighten only the four bottom bolts, leaving the top middle bolt snug but not loose. I usually have to re-tighten the exhaust manifold bolts every 6 months.
Regards,
Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] engine clicking... header leak... [message #142116 is a reply to message #142114] |
Fri, 02 September 2011 14:24 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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The Remflex makes for both application.
On Fri, Sep 2, 2011 at 12:10 PM, Thomas Phipps <tph1pp5@yahoo.com> wrote:
>
>
> Check with JmK for Remlex exhaust gaskets. Â They work. period. Â I know that He has them for stock manifolds, I am not sure about headers, but if they are out there, he has them.
> Tom Phipps,MS II
> Bound for Goshen in 4days.
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Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
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| Re: [GMCnet] engine clicking... header leak... [message #142128 is a reply to message #142106] |
Fri, 02 September 2011 15:26 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Tightening will not work. Replace the gasket.
On Fri, Sep 2, 2011 at 10:29 AM, Ek_Lektro <eklektro@gmail.com> wrote:
> Need a little advise please:
> My '78 403 has had what i'm guessing is a valve clicking noise for the past
> year or so, coming from the top left of the engine.
> Lately its become quite loud after starting up with a cold engine... and of
> course it dies down a bit after warming up,
> but never fully goes away. i know this is pretty common, and probably a
> sign of eventual need for a valve job.
> But recently i discovered a couple possible reasons why its been so much
> louder lately:
>
> A friend helped me with some work last summer, part of which was changing
> the spark plugs (but we didn't get to changing the wires at that time since
> the shop was out of stock...) So when i was finally changing wires last
> week, i found that one of the spark plugs was really loose, like 2 turns
> away from falling out. Not sure if it was that loose to begin with, or if
> i'd been driving it for a whole year like that, but i put in a new plug to
> be safe and tightened it up.
> Was hoping that this might've been the cause for the clicking noise, 'cause
> at times the click has such a high pitch to it, it almost sounds electrical.
> But no... the click remained. So i took a hose and used it as a
> stethoscope to pinpoint the noise, and i found out that i have an air leak
> between the headers and the manifold. Interestingly the leak is immediately
> below the particular spark plug that was so incredibly loose. Is this just a
> coincidence? or did something go out of whack by driving for a year with a
> loose plug? Anyway, i tried to tighten up the 2 bolts at that part of the
> header, but apparently not tight enough, 'cause i still have the air leak,
> and the clicking noise is only slightly dampened. I guess the next step is
> to try to loosen all of the header bolts, and try to tighten them up in
> sequence, to see if i can get rid of the leak completely, and hopefully the
> clicking noise will not be as severe. i don't recall there being any kind of
> header gasket to
> replace, so beyond getting some special heavy-duty 7/16" wrench into those
> tight spaces, are there are any tricks to solving header leaks?
>
> Thanks in advance for any advice!
> Greg
> '78 eleganza II
> PS: a little history on the coach:
> new Thorley headers installed in '98... Re-installed with a rebuilt engine
> in '02
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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| Re: [GMCnet] engine clicking... header leak... [message #142131 is a reply to message #142128] |
Fri, 02 September 2011 15:48 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Greg,
It sounds to me like you don't have a mechanical problem with the lifter. A small header or manifold gasket leak can sound an awful lot like lifter noise. The give away here is that it diminishes as the engine warms up. That is because the expansion of the steel, as it heats up, makes the leak smaller. I'm betting that if you use a set of Remflex gaskets on your headers, you will eliminate what sounds like a lifter noise as well as the exhaust leak.
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] engine clicking... header leak... [message #142134 is a reply to message #142131] |
Fri, 02 September 2011 16:03 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Greg, a trick that I use is to use a piece of card stock cut in a 1" wide X
6" long. Hold it by your header leak, and see if it moves in tempo with your
noise. Work for me and is cheap. Like the others say, Remflex it, and pay
attention to the tightening proceedure. Leave the top center bolt barely
tight.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Fri, Sep 2, 2011 at 1:48 PM, Carl Stouffer <carljr3b@yahoo.com> wrote:
>
>
> Greg,
>
> It sounds to me like you don't have a mechanical problem with the lifter.
> A small header or manifold gasket leak can sound an awful lot like lifter
> noise. The give away here is that it diminishes as the engine warms up.
> That is because the expansion of the steel, as it heats up, makes the leak
> smaller. I'm betting that if you use a set of Remflex gaskets on your
> headers, you will eliminate what sounds like a lifter noise as well as the
> exhaust leak.
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] engine clicking... header leak... [message #142140 is a reply to message #142134] |
Fri, 02 September 2011 16:50 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Senior Member |
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Greg,
All the advice you have been given is correct IF YOU HAVE A LEAKING GASKET.
However, I recently had an exhaust leak on the passenger side. I could feel the exhaust pulse with my hand at the center(double pipe ) of my old and tired Thorley Header. I carefully replaced the gasket as recommended by others here. The leak still persisted even though I was certain I had a good seal from the gasket.
I removed the header from the coach and upon close inspection found that the leak was through a small hole in the flange between the 2 center header pipes. No gasket seals that area.
A good welder could probably have repaired the leak but my headers are quite old and I was concerned that it might start to leak in another place.
The good news is that Thorley honored the "Lifetime Warranty'(with a little urging from Jim K.)
I had to wait a bit for a new production run but I have new headers and I'm a happy customer.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] engine clicking... header leak... [message #142255 is a reply to message #142106] |
Sat, 03 September 2011 12:36 |
Ek_Lektro
Messages: 167
Registered: March 2011
Karma: 2
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On Sep 2, 2011, at 1:57 PM, gmclist-request@temp.gmcnet.org wrote:
> Hold it by your header leak, and see if it moves in tempo with your noise.
Yes, 90% sure its a leak at the gasket...
> Remflex it, and pay attention to the tightening proceedure.
OK, i'll be adding this to the list... for the winter work!
In the meantime, i once read somewhere that its "bad for the engine" to drive it with any leaks like this...
Is this really true?... perhaps under hard driving conditions (steep hills in the heat)?
Despite the minor annoyance of the clicking noise,
i'm guessing its a pretty minor leak, and i don't have any plans for heavy duty driving the next few months...
So... i'm guessing its OK to put this off for a bit?
It sounds to me like you don't have a mechanical problem with the lifter.
> A small header or manifold gasket leak can sound an awful lot like lifter
> noise. The give away here is that it diminishes as the engine warms up.
Yeah, this is good news,... and that's what i was guessing, 'cause i demonstrated the noise for Miguel back when
it was just starting, and he didn't think it was a problem.
But the noise has amplified a bit since then, and i guess the cause for alarm was when discovering the super-loose
spark plug in the exact same region of the leak! Coincidence... keeps us on our guard :)
> pour a pint or so of Marvel Mystery Oil in the oil fill. Sometimes it helps, but at least it will clean them up a bit.
If its just a header leak and not a lifter problem, then is this still recommended, as a periodic maintenance thing?
There's a little valve cover oil leak as well, but nothing major..
OK, thanks all!
G
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| Re: [GMCnet] engine clicking... header leak... [message #142259 is a reply to message #142255] |
Sat, 03 September 2011 13:11 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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The one circumstance that is harmful to the engine when discussing exhaust
leaks relates to exhaust valves being exposed to oxygenated air when they
are red hot (normal operating temp when under way) The normal composition of
exhaust gasses in the headers that do not have leaks that are great enough
to allow not only exhaust gasses to escape, but also air to freeley enter
when there is a reversion of pressures in the header, are devoid of oxygen.
Valves cannot burn (oxidize) if there is no oxygen present in the gasses
surrounding them. That is why they can run red hot for 100 thousand + miles
and not burn away. If there is oxygen present when those valves are at
operating temp., valve and seat life is drastically reduced. Major leaks in
the header flanges, or very short header length without tail pipes as in
open headers can and does lead to premature valve failures. Obviously, if a
spark plug was loose enough to allow extra oxygen to be inhaled during the
intake stroke, that particular cylinder would have a lean mixture.
Speculation prevails from here on in. If a wet/dry compression check reveals
no unusual problems, and the leak is minor, fix as time constraints allow.
If the leak is major, you run the risk of trenching the mating surface
between the header flange and the cylinder head. If the compression is low,
the head has to come off and the mating surface can be addressed then. Ain't
GMCs fun?
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, Sep 3, 2011 at 10:36 AM, Ek_Lektro <eklektro@gmail.com> wrote:
> On Sep 2, 2011, at 1:57 PM, gmclist-request@temp.gmcnet.org wrote:
>
> > Hold it by your header leak, and see if it moves in tempo with your
> noise.
>
> Yes, 90% sure its a leak at the gasket...
>
> > Remflex it, and pay attention to the tightening proceedure.
>
> OK, i'll be adding this to the list... for the winter work!
> In the meantime, i once read somewhere that its "bad for the engine" to
> drive it with any leaks like this...
> Is this really true?... perhaps under hard driving conditions (steep hills
> in the heat)?
> Despite the minor annoyance of the clicking noise,
> i'm guessing its a pretty minor leak, and i don't have any plans for heavy
> duty driving the next few months...
> So... i'm guessing its OK to put this off for a bit?
>
> It sounds to me like you don't have a mechanical problem with the lifter.
> > A small header or manifold gasket leak can sound an awful lot like lifter
> > noise. The give away here is that it diminishes as the engine warms up.
>
> Yeah, this is good news,... and that's what i was guessing, 'cause i
> demonstrated the noise for Miguel back when
> it was just starting, and he didn't think it was a problem.
> But the noise has amplified a bit since then, and i guess the cause for
> alarm was when discovering the super-loose
> spark plug in the exact same region of the leak! Coincidence... keeps us
> on our guard :)
>
> > pour a pint or so of Marvel Mystery Oil in the oil fill. Sometimes it
> helps, but at least it will clean them up a bit.
>
> If its just a header leak and not a lifter problem, then is this still
> recommended, as a periodic maintenance thing?
> There's a little valve cover oil leak as well, but nothing major..
>
> OK, thanks all!
> G
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] engine clicking... header leak... [message #142281 is a reply to message #142106] |
Sat, 03 September 2011 18:00 |
Richard Brown
Messages: 281
Registered: May 2009
Karma: 1
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Senior Member |
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It can't hurt. I don't run it full-time in an engine; I put it in a few days before I change the oil.
I once owned a Buick V-6 that had a rear main seal leak in the rope seal & MMO softened the rope seal enough to slow down the leak considerably. It may also soften up that leaky gasket & slow down that leak, as well. I also use it on lawn mowers that I'm storing for the winter. I pull the plug, squirt some in the cylinder, & spin it over a few times. Keeps the rings & valves from sticking. I also change the oil before I start it in the spring. It may be snake oil, but if it is, it's made from good snakes...
Richard & Carol Brown
1974 Eleganza SE
"DILLIGAF"
Lindale, Tx. 75771
903-881-0192
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Richard & Carol Brown
1974 Eleganza SE
1174 Hickory Hills Dr.
Murchison, TX. 75778
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| Re: [GMCnet] engine clicking... header leak... [message #142304 is a reply to message #142281] |
Sat, 03 September 2011 21:17 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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In a previous posting I suggested the same thing. We use Marvel or ATF on air cooled airplane engines that have been sitting for a long time. It will soften up the goo and combustion deposits as long as you haven't been running synthetic oil. If you have been running synthetic, just start disassembling the engine.
Obviously Marvel or ATF is not going to fix a mechanical problem. I soaked one cylinder with Marvel / ATF on my airplane several times trying to free up a stuck ring. I flew that engine for over a year and it never got better. I finally pulled that cylinder and found one broken compression ring.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] engine clicking... header leak... [message #142308 is a reply to message #142106] |
Sat, 03 September 2011 21:28 |
Dan Winchester
Messages: 61
Registered: August 2006
Karma: 0
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Member |
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There is an issue with not taking care of an exaust manafold leak, over time the hot gasses will erode the head. In my case it necessitated removing the heads and having the manafold mating surface machined flat, not a cheap process.
Dan Winchester
www.dwinchester.com
----- Reply message -----
From: "Ek_Lektro" <eklektro@gmail.com>
Date: Sat, Sep 3, 2011 10:36 am
Subject: [GMCnet] engine clicking... header leak...
To: <gmclist@temp.gmcnet.org>
On Sep 2, 2011, at 1:57 PM, gmclist-request@temp.gmcnet.org wrote:
> Hold it by your header leak, and see if it moves in tempo with your noise.
Yes, 90% sure its a leak at the gasket...
> Remflex it, and pay attention to the tightening proceedure.
OK, i'll be adding this to the list... for the winter work!
In the meantime, i once read somewhere that its "bad for the engine" to drive it with any leaks like this...
Is this really true?... perhaps under hard driving conditions (steep hills in the heat)?
Despite the minor annoyance of the clicking noise,
i'm guessing its a pretty minor leak, and i don't have any plans for heavy duty driving the next few months...
So... i'm guessing its OK to put this off for a bit?
It sounds to me like you don't have a mechanical problem with the lifter.
> A small header or manifold gasket leak can sound an awful lot like lifter
> noise. The give away here is that it diminishes as the engine warms up.
Yeah, this is good news,... and that's what i was guessing, 'cause i demonstrated the noise for Miguel back when
it was just starting, and he didn't think it was a problem.
But the noise has amplified a bit since then, and i guess the cause for alarm was when discovering the super-loose
spark plug in the exact same region of the leak! Coincidence... keeps us on our guard :)
> pour a pint or so of Marvel Mystery Oil in the oil fill. Sometimes it helps, but at least it will clean them up a bit.
If its just a header leak and not a lifter problem, then is this still recommended, as a periodic maintenance thing?
There's a little valve cover oil leak as well, but nothing major..
OK, thanks all!
G
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| Re: [GMCnet] engine clicking... header leak... [message #142349 is a reply to message #142255] |
Sun, 04 September 2011 08:01 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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Greg,
Exhaust manifold leaks are like a hole in a dike. The constant flow of hot
exhaust gasses will cause erosion of metal between the manifold and engine.
It is an easy job to replace an exhaust manifold gasket. The existing bolts
must go back in the same locations. (Different lengths.)
> Yes, 90% sure its a leak at the gasket...
>
> > Remflex it, and pay attention to the tightening proceedure.
>
> OK, i'll be adding this to the list... for the winter work!
> In the meantime, i once read somewhere that its "bad for the engine" to
> drive it with any leaks like this...
> Is this really true?... perhaps under hard driving conditions (steep hills
> in the heat)?
> Despite the minor annoyance of the clicking noise,
> i'm guessing its a pretty minor leak, and i don't have any plans for heavy
> duty driving the next few months...
> So... i'm guessing its OK to put this off for a bit?
> OK, thanks all!
>
--
Steve Ferguson
Sierra Vista, AZ
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