455 head gasket sealent or no sealant

R

rgogan

New member
Sep 20, 2004
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Just about ready to pull my cylinder head for a cylinder #5 with only 55psi compression. Bought a Victor Reinz composite head gasket. Shop manual
for GMC states "coat both sides of the head gasket with GM #10050026". Of course, that sealant is no longer available and the Victor Reinz web site
state no sealant should be used on their gaskets unless the manufacturer recommends it.
The gasket is a composite one, not one of the newer multilayer steel ones that never takes a sealant because it comes with some type of sealant
already on the gasket.
Any advice on whether to use a sealant and if so what sealant replaces the GM #10050026 sealant?
 
R.

Yes, that sealant is NLA and just as well. The OE head gasket for a 455 was an embossed steel shim. It required the coating to make the microseal
with the head and deck surface.

I have not kept tabs on what Victor is doing these days, but most modern head gaskets are coated with a dry sealant and I know Victor used to use the
same teflon material that we did at one time, but I have not kept tabs.

Just make sure that the surfaces are both clean and as flat as you can make them with an oil stone. (A hand stone will only take off high spots that
might have been created.) Chase the thread in the block with a good tap and solvent wash the threads before you blow them clear. A light coat of oil
on the bolt threads and under the heads is all that is required for consistent tension.

If you are reusing the head bolts, be cautious, because I found mine to be very close to yield.
It is not practical with an assembled 455 to do a hot re-torque, but if you let the assembly sit a day after your final torque pass and then come back
and repeat that final pass, you may get a few more degrees on many of the head bolts. This is "free tension" and can only help in the success of the
assembly.

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
 
Thanks for the advice. Looks like I am bolting it up dry. BTW, I did have a used head rebuilt by a shop so the head mating surface should be perfect.
For checking the flatness of the deck, is a carpenters square straight enough to use?
 
I've used Hylomar spray on head gaskets in the past with good results, but only on "dry" gaskets, which seems to be a rare thing nowadays. Most new
gaskets I've seen lately have some sort of soft coating on them, and I leave off the spray on these.

Interestingly, the Felpro composite gaskets I recently bolted down on my 455 appeared to have a thin, semi-transparent blue coating that looked very
similar to dried Hylomar...

I've also used the Hylomar spray with good results when reusing MLS head gaskets such as a Cometic gasket. After the first use, the coating on the
MLS gaskets ends up stuck to the parts, so a recoat is needed if you are going to reuse. (Now, I only reuse head gaskets on performance or race
motors I know I will be tearing down frequently... Would not reuse a gasket on my motorhome, wife's daily driver, etc.)

For your Victor Reinz gaskets, if the surface feels like uncoated metal, I would probably coat just to be safe... If they have some sort of soft
coating, rubber coating, etc., would install them dry....

Matt: How can you tell if a head bolt is close to yield? I believe it has to do with somehow measuring bolt stretch, but I never really understood
how to tell...
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
You know, thinking back on this, I believe MLS gaskets have come a long way... I had an 05 GTO and I believe all of them came from the factory with a
couple tablets of the GM equivalent of "Bars Leaks" in the coolant system. I remember people getting online when the cars were new and seeing gunk on
the inside of their overflow tanks, and thinking it was some sort of corrosion issue, when in reality, it was just the Bars Leaks in there....

Apparently, someone realized 25 cents worth of stop leak reduced the number of head gasket related warranty claims on the early LS engines, so for a
time there, they all came that way. I can only assume it was due to the coating used on MLS gaskets at that time was not up to snuff? If anyone
knows otherwise, I would be interested to hear...

It seemed to have stopped by '09 anyway, as the overflow on our G8 looked pristine when it was new...
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
>
>
> Matt: How can you tell if a head bolt is close to yield? I believe it has to do with somehow measuring bolt stretch, but I never really
> understood how to tell...

Mark(?),

You are going to love this answer....

By Feel... If the fastener does not continually require increasing load for the angle of rotation, it is probably failing.

If you are using a beam and pointer wrench, this is pretty easy to see. If it is a preset click type, you have to pay attention.

There are lots of expensive lab instruments we used to (and I no longer have access to) use to do this, so my best recommendation is that if it
doesn't feel right, stop.

My engine was on its third assembly and I have reason to believe those that did number 2 were not the best technicians.

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
 
> >
> >
> > Matt: How can you tell if a head bolt is close to yield? I believe it has to do with somehow measuring bolt stretch, but I never really
> > understood how to tell...
>
> Mark(?),
>
> You are going to love this answer....
>
> By Feel... If the fastener does not continually require increasing load for the angle of rotation, it is probably failing.
>
> If you are using a beam and pointer wrench, this is pretty easy to see. If it is a preset click type, you have to pay attention.
>
> There are lots of expensive lab instruments we used to (and I no longer have access to) use to do this, so my best recommendation is that if it
> doesn't feel right, stop.
>
> My engine was on its third assembly and I have reason to believe those that did number 2 were not the best technicians.
>
> Matt

So kinda that feel you get when torqueing down a bolt just before it breaks? Where it almost feels like it gets easier to turn?

If so, I think I was ok at least... I know our bolts are supposed to be reusable, but when I was torqueing down my heads a few weeks ago, I looked
around for new bolts just as insurance, but I did not find any available outside of ARPs, which I figured was overkill for our motors...


--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
rgogan - As far as using a carpenters square I would not use one. Eighteen inch straight edge and feeler gauge is cheap. Buy yourself a new one and
check the head and block. Did I understand your post that you are replacing just one head?
 
About torqueing head bolts or any bolts for that matter. When what is being installed has multiple fasteners
it's not NICE when the last fastener in the torque sequence on the final torque breaks off at the mating surface.
Do you attempt to get the piece out ? I did and i got it out. Or do take the whole thing apart and install new
fasteners in all the holes and a new gasket? Any where do you get the bolts on a Sunday afternoon?
There are documented procedures to sort of check visually bolts for stretch BEFOREO installation. I'll never
again do a head without checking the bolts or using new bolts.
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
 
> About torqueing head bolts or any bolts for that matter. When what is being installed has multiple fasteners
> it's not NICE when the last fastener in the torque sequence on the final torque breaks off at the mating surface.
> Do you attempt to get the piece out ? I did and i got it out. Or do take the whole thing apart and install new fasteners in all the holes and a
> new gasket?
> Any where do you get the bolts on a Sunday afternoon?
> There are documented procedures to sort of check visually bolts for stretch BEFORE installation.
> I'll never again do a head without checking the bolts or using new bolts.

Dave et al,

One at a time here.

If you set all the bolts down on a table and compare the length of all the similar parts, you might spot one that is a little longer. That's a hope.

Of all, you can match the threaded section. They should all be a lot alike. If one has a section of slightly longer pitch, don't use that one.

The essence of any bolted assembly is creating the tension in the fasteners. If you broke one and had to take the assembly apart to clear that issue,
as long as the gasket is not hurt in the disassembly, put it back in. There is a problem, if the gasket is coated with anything adhesive, you chances
of being able to re-install that gasket is exceeding small.

With most newer engines, a gasket kit that includes a head gasket will also include a set of new head bolts. Most modern passcar engines use bolts
that are "Torque to Yield" (TTY) and these cannot and should not be reused.

How does a guy know if this is the case?? Read the tensioning procedure in the manual or kit. If it says torque to some nominal and then make passes
(usually 2) of an angle (typically 90°), that is a recipe for field install of TTY fasteners.

If this is an engines first disassembly, those bolts may look real good, and in some cases they can be reused (don't count on this) because in the
engine plant there is special equipment to tension these bolts. They can hit a 1% yield. The manual torque wrench that can do this is several
thousand dollars.

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
 
Do not use if they look like either of the above bolts. :d
I could definitely feel the bolt stretching, but backed it out before it broke.

Weirdest head bolts I've used were on a Audi inline-5 20-valve engine, they looked like they had an Acme thread running around them down to where the
real thread started, OE ones were made of unobtainium, but I asked and apparently they could be used twice, so I reused.
I don't imagine it's too pricey to replace them on a 455 Olds.


Also, someone mentioned Hylomar, beware, it's not the same stuff in every country, it's a marketing term.
--
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model
 
I am just replacing the driver's side head. I had only 55psi on cylinder #5 with all the others reading 160psi. This occurred after a water pump seal
blew and I overheated the engine. I presume the head cracked or I blew out the head gasket. I did order a carbide scraper to clean the block deck
surface and I bought a engine rebuilder's 24 inch straight edge that is spec'ed to .001" tolerance.
 
Just pulled my steel intake manifold off for the first time. I had seen pictures of the charred oil on the turkey tray from other posters but was
shocked to see it on my engine. Cannot believe GM engineers would design a system that could drop this charcoal like material into the valley and the
cam. BTW, I could only pull the intake manifold off after using a sharpened dry wall knife to break the turkey tray seals. No amount of pounding or
using an air hammer would break it free.

The distributor was also frozen, but after several days of PB blaster and using a 1" wrench to wiggle the square fitting on the distributor shaft, I
was able to break it free. One poster gave me the suggestion of not muscle torqueing it free, but imagining that it was a square peg in a square hole
and wiggling it back and forth as if you were trying to round the hole. Worked great!

Now to clean up the mess that occurred after removing the turkey tray and replacing the head and gasket. I did buy Jim K's recommended sealer for the
intake manifold gasket and am going dry on the head gasket.
 
What you have found id not uncommon build up on the turkey tray. It is caused by the high temp of the exhaust gases and that pass back and forth on the cross over and sometimes can cause crack in the manifold. You should check yours and that will cause the motor to run weirdly. That is why the common practice is to block the cross overs at the head/manifold meeting area. If your manifold is cracked then you may want to fill the cross over in the manifold. Some have used por-rock or Hard rock a produce that is used to fill the block water passages in a comp motor and some have used aluminum to fill the crossover. Another alternative is to replace the manifold with another CI unit or one of the 2 aluminum manifolds available..

Pro-Rock or Hard rock http://www.gmcmhphotos.com/photos/intake-manifold-pics/p26357-installing-aluminum-intake.html

https://www.summitracing.com/search/brand/moroso/part-type/block-fillers?SortBy=Default&SortOrder=Ascending
https://www.summitracing.com/search/brand/hard-blok/part-type/block-fillers

Edelbrock Aluminum Maniford http://www.gmcmhphotos.com/photos/intake-manifold-pics/p26357-installing-aluminum-intake.html

Call Jim K

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan

>
> Just pulled my steel intake manifold off for the first time. I had seen pictures of the charred oil on the turkey tray from other posters but was
> shocked to see it on my engine. Cannot believe GM engineers would design a system that could drop this charcoal like material into the valley and the
> cam. BTW, I could only pull the intake manifold off after using a sharpened dry wall knife to break the turkey tray seals. No amount of pounding or
> using an air hammer would break it free.
>
> The distributor was also frozen, but after several days of PB blaster and using a 1" wrench to wiggle the square fitting on the distributor shaft, I
> was able to break it free. One poster gave me the suggestion of not muscle torqueing it free, but imagining that it was a square peg in a square hole
> and wiggling it back and forth as if you were trying to round the hole. Worked great!
>
> Now to clean up the mess that occurred after removing the turkey tray and replacing the head and gasket. I did buy Jim K's recommended sealer for the
> intake manifold gasket and am going dry on the head gasket.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
 
Robert,

What I see no mention of in your posting is "blocking the exhaust
crossover ports". That's ESSENTIAL -- that crossover is the cause of all
the junk you found on the turkey tray, and it will continue to be
generated, and dropping right on your cam, etc., if you don't seal those
crossovers -- in some way (I know of half a dozen).

Ken H.

> Just pulled my steel intake manifold off for the first time. I had seen
> pictures of the charred oil on the turkey tray from other posters but was
> shocked to see it on my engine. Cannot believe GM engineers would design
> a system that could drop this charcoal like material into the valley and the
> cam. BTW, I could only pull the intake manifold off after using a
> sharpened dry wall knife to break the turkey tray seals. No amount of
> pounding or
> using an air hammer would break it free.
>
> The distributor was also frozen, but after several days of PB blaster and
> using a 1" wrench to wiggle the square fitting on the distributor shaft, I
> was able to break it free. One poster gave me the suggestion of not
> muscle torqueing it free, but imagining that it was a square peg in a
> square hole
> and wiggling it back and forth as if you were trying to round the hole.
> Worked great!
>
> Now to clean up the mess that occurred after removing the turkey tray and
> replacing the head and gasket. I did buy Jim K's recommended sealer for the
> intake manifold gasket and am going dry on the head gasket.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
What caused that "junk" as you call it, is by not changing oil often
enough, combined with that unblocked off exhaust crossover. All that heat
turns that oil into coke. I don't have a high regard for turkey tray
gaskets either. All that heat can and frequently does crack the intake
manifolds. They run really crappy when cracked, also.
Jim Hupy
Salem, Oregon

> Robert,
>
> What I see no mention of in your posting is "blocking the exhaust
> crossover ports". That's ESSENTIAL -- that crossover is the cause of all
> the junk you found on the turkey tray, and it will continue to be
> generated, and dropping right on your cam, etc., if you don't seal those
> crossovers -- in some way (I know of half a dozen).
>
> Ken H.
>
> On Wed, Jun 9, 2021 at 3:13 PM Robert J. Gogan

>
> > Just pulled my steel intake manifold off for the first time. I had seen
> > pictures of the charred oil on the turkey tray from other posters but was
> > shocked to see it on my engine. Cannot believe GM engineers would design
> > a system that could drop this charcoal like material into the valley and
> the
> > cam. BTW, I could only pull the intake manifold off after using a
> > sharpened dry wall knife to break the turkey tray seals. No amount of
> > pounding or
> > using an air hammer would break it free.
> >
> > The distributor was also frozen, but after several days of PB blaster and
> > using a 1" wrench to wiggle the square fitting on the distributor shaft,
> I
> > was able to break it free. One poster gave me the suggestion of not
> > muscle torqueing it free, but imagining that it was a square peg in a
> > square hole
> > and wiggling it back and forth as if you were trying to round the hole.
> > Worked great!
> >
> > Now to clean up the mess that occurred after removing the turkey tray and
> > replacing the head and gasket. I did buy Jim K's recommended sealer for
> the
> > intake manifold gasket and am going dry on the head gasket.
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
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