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455 head gasket sealent or no sealant

RJ
Robert J. Gogan
Wed, May 26, 2021 5:08 PM

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?

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?
MC
Matt Colie
Wed, May 26, 2021 5:36 PM

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

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
RJ
Robert J. Gogan
Wed, May 26, 2021 7:47 PM

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?

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?
MS
Mark Sawyer
Wed, May 26, 2021 11:29 PM

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

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
MS
Mark Sawyer
Wed, May 26, 2021 11:39 PM

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

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
MC
Matt Colie
Thu, May 27, 2021 12:43 AM

TR 1 wrote on Wed, 26 May 2021 19:29

<snip>

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

TR 1 wrote on Wed, 26 May 2021 19:29 > <snip> > > 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
MS
Mark Sawyer
Thu, May 27, 2021 2:04 PM

Matt Colie wrote on Wed, 26 May 2021 19:43

TR 1 wrote on Wed, 26 May 2021 19:29

<snip>

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

Matt Colie wrote on Wed, 26 May 2021 19:43 > TR 1 wrote on Wed, 26 May 2021 19:29 > > <snip> > > > > 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
PN
Paul Nadel
Thu, May 27, 2021 11:42 PM

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?

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?
DK
Dave King
Fri, May 28, 2021 12:13 PM

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 BEFOREO installation. I'll never again do a head without checking the bolts or using new bolts. -- DAVE KING lurker, wannabe Toronto, Ontario, Canada
MC
Matt Colie
Fri, May 28, 2021 1:51 PM

kingd wrote on Fri, 28 May 2021 08:13

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

kingd wrote on Fri, 28 May 2021 08:13 > 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