Exhaust Manifold Bolts & Lubricants

R

robert mueller

New member
Jul 4, 2007
17,586
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G'day,

I think we have discussed which bolts are best to use for the exhaust manifold but couldn't find a definitive answer searching the
Forum; hence this thread.

I'm sitting at my desk and typing this from memory using the MM and PB as reference.

OEM Bolts
Material: Steel
Grade: ??
Diameter: 3/8 Inch
Thread: 16 Threads Per Inch
Length: 1 1/4 Inches
Lubricant: None
Torque: 25 foot pounds

Query: What material bolt is the best to use for the exhaust manifold?

OEM Bolts
Material:
Grade:
Diameter: 3/8 Inch
Thread: 16 Threads Per Inch
Length: 1 1/4 Inches
Lubricant:
Torque: Foot Pounds

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
 
Rob,
Do you really mean "best", or did you mean to say "reliably adequate"?

I just finished researching bolts for the exhaust manifolds on my turbo powered truck. My application is known for having seized and broken bolts.

For the "best" bolt in a high temp exhaust environment, inconel type material is often recommended, but it gets costly real quick.

For "reliably adequate" fasteners, there are many less costly materials that will suffice. I've seen all kinds of online recommendations, so I'll let everyone else chime in and share their wisdom. I might learn something. :)

Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)

>
> G'day,
>
> I think we have discussed which bolts are best to use for the exhaust manifold but couldn't find a definitive answer searching the
> Forum; hence this thread.
>
> I'm sitting at my desk and typing this from memory using the MM and PB as reference.
>
> OEM Bolts
> Material: Steel
> Grade: ??
> Diameter: 3/8 Inch
> Thread: 16 Threads Per Inch
> Length: 1 1/4 Inches
> Lubricant: None
> Torque: 25 foot pounds
>
> Query: What material bolt is the best to use for the exhaust manifold?
>
> OEM Bolts
> Material:
> Grade:
> Diameter: 3/8 Inch
> Thread: 16 Threads Per Inch
> Length: 1 1/4 Inches
> Lubricant:
> Torque: Foot Pounds
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Les,

HOOLEE DOOLEE !

http://www.zieglerbolt.com/templates/product_listprice.asp?ProductGuid=37C125BHB%2FINC&GroupGuid=58348

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Les Burt

Rob,
Do you really mean "best", or did you mean to say "reliably adequate"?

I just finished researching bolts for the exhaust manifolds on my turbo powered truck. My application is known for having seized and
broken bolts.

For the "best" bolt in a high temp exhaust environment, inconel type material is often recommended, but it gets costly real quick.

For "reliably adequate" fasteners, there are many less costly materials that will suffice. I've seen all kinds of online
recommendations, so I'll let everyone else chime in and share their wisdom. I might learn something. :)

Les Burt
 
Yup.

I looked for inconel studs and found them to be just as costly.

I recall reading here that using a gr8 bolt is a waste of $$ as the heat cycles will degrade it to something similar in strength to a gr5.

Typical 300 series stainless is too soft and will seize into the Head, making future removal lots of fun.

I ended up using the factory recommended bolts on my truck as they were the lowest cost option that came close to providing adequate service life. They appear to be some sort of 400 series stainless, as they are slightly magnetic, but do not rust.

Lots of nickel anti-seize and I'm confident they will survive long enough to keep me happy.

Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)

>
> Les,
>
> HOOLEE DOOLEE !
>
> http://www.zieglerbolt.com/templates/product_listprice.asp?ProductGuid=37C125BHB%2FINC&GroupGuid=58348
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: Les Burt
>
> Rob,
> Do you really mean "best", or did you mean to say "reliably adequate"?
>
> I just finished researching bolts for the exhaust manifolds on my turbo powered truck. My application is known for having seized and
> broken bolts.
>
> For the "best" bolt in a high temp exhaust environment, inconel type material is often recommended, but it gets costly real quick.
>
> For "reliably adequate" fasteners, there are many less costly materials that will suffice. I've seen all kinds of online
> recommendations, so I'll let everyone else chime in and share their wisdom. I might learn something. :)
>
> Les Burt
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
G'day,

STOP THE PRESSES!

I just received an off net message from a GMCer I respect greatly and he noted that he replaces the five bolts with steel studs and
steel nuts.

I never thought of that, it makes R&R'ing the manifold easier as you can hang it on the studs and if the nut is seized on the stud
you can cut / grind it off.

Would brass nuts stand up to the heat?

How about stainless steel nuts?

How about Monel:

http://www.zieglerbolt.com/templates/product_listprice.asp?ProductGuid=37CNFH%2FMON&GroupGuid=58348

That's better!

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Les Burt
Sent: Wednesday, October 12, 2016 12:08 PM
To: gmclist
Subject: Re: [GMCnet] Exhaust Manifold Bolts & Lubricants

Yup.

I looked for inconel studs and found them to be just as costly.

I recall reading here that using a gr8 bolt is a waste of $$ as the heat cycles will degrade it to something similar in strength to
a gr5.

Typical 300 series stainless is too soft and will seize into the Head, making future removal lots of fun.

I ended up using the factory recommended bolts on my truck as they were the lowest cost option that came close to providing adequate
service life. They appear to be some sort of 400 series stainless, as they are slightly magnetic, but do not rust.

Lots of nickel anti-seize and I'm confident they will survive long enough to keep me happy.

Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)

>
> Les,
>
> HOOLEE DOOLEE !
>
> http://www.zieglerbolt.com/templates/product_listprice.asp?ProductGuid=37C125BHB%2FINC&GroupGuid=58348
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: Les Burt
>
> Rob,
> Do you really mean "best", or did you mean to say "reliably adequate"?
>
> I just finished researching bolts for the exhaust manifolds on my turbo powered truck. My application is known for having seized
and
> broken bolts.
>
> For the "best" bolt in a high temp exhaust environment, inconel type material is often recommended, but it gets costly real quick.

>
> For "reliably adequate" fasteners, there are many less costly materials that will suffice. I've seen all kinds of online
> recommendations, so I'll let everyone else chime in and share their wisdom. I might learn something. :)
>
> Les Burt
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Bronze nuts will withstand the strain and heat, I've seen them on some factory exhaust manifold studs at the pipe/manifold connection. Brass is pretty
soft and will probably strip unless it is a long nut.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
I frequently attach headers on Olds engines using studs and brass/bronze
nuts. I prefer sae fine threads with the nuts. Long nuts will work but, are
hard to remove after extended service. Lock washers are of little use, but
heavy sae flat washers work very well. Just what I do.
Jim Hupy
Salem, Or

> Bronze nuts will withstand the strain and heat, I've seen them on some
> factory exhaust manifold studs at the pipe/manifold connection. Brass is
> pretty
> soft and will probably strip unless it is a long nut.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I had multiple problems with steel exhaust bolts on my airplane. An airplane engine runs much hotter than an automotive one since the engine runs %65
to %80 of power for hours on end. I burn 10 to 12 gallons per hour. My EGT runs around 1500 degrees during that time.

I went with steel studs, brass / bronze nuts, and high temp anti-Seize. I usually remove that exhaust every second year to inspect for exhaust leaks.
(The cabin heater is wrapped around the muffler so exhaust leaks are a major worry) The brass nuts and anti-seize really worked well for me for the
last 25 years or so.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
For the past 2-3 change cycles, I've used this McMaster-Carr "high
temperature" threaded rod to make studs:
99065A130 http://www.mcmaster.com/#99065A130 Brass nuts are easy to
remove, but tend to flare out on the loaded side. Since I double-nut them,
that's an annoyance when I loosen the top one and try to remove them both
with a deep socket. Still the best choice I've found.

Ken H.

> Rob,
> Do you really mean "best", or did you mean to say "reliably adequate"?
>
> I just finished researching bolts for the exhaust manifolds on my turbo
> powered truck. My application is known for having seized and broken bolts.
>
> For the "best" bolt in a high temp exhaust environment, inconel type
> material is often recommended, but it gets costly real quick.
>
> For "reliably adequate" fasteners, there are many less costly materials
> that will suffice. I've seen all kinds of online recommendations, so I'll
> let everyone else chime in and share their wisdom. I might learn something.
> :)
>
 
Ready?
Here he comes.....

Do Not Use Grade 8 fasteners on anything exhaust.
Gr.8 achieve the better strength with a combination of alloy and heat treatment.
The heat treatment can be normalized away at exhaust manifold temperatures.
The alloy encourages galling and seizing.

If you have to use Gr.5, you should still be careful.
Gr.5 achieve their better strength with a lesser alloy and minimal heat treatment.
That amount of heat treatment can be lost, but it will not matter much.
The alloy is still more prone to galling.

The OE fasteners are probably Gr.2 or 3 or maybe a proprietary in the TZE case.
TZE Special Note: The stock fasteners are listed at 300M. That is a higher quality than an off the shelf Gr.2. The grade is not specified.
In any case, use of as much anti-seize and you can will do no harm.
If you have an oxygen sensor, you have to use nickle based anti-seize. The copper based (like Fel-Pro C-5) also contain lead.

What ever you do, DO NOT exceed the manufacture's recommended install torque.
If you go with a stud and a bronze (brass probably won't make it) nut, that is a good idea.
But, if you have a fine thread nut, that will change (probably increase) the fastener tension for the same final torque.
I say "Probably" because there are too many other variables. Stick with the manual.

If you can, do a thermal cycle and then pull on the wrench at the install torque again. If they move, that's nice, and if they don't, leave them
alone.
This is largely going to be an artifact of the relaxation of the gasket material. If you get movement, that is "free" clamp load and it is desirable.


This is all based on years in engine development and testing and other relative experience.

I'll go sit down now......
Matt
--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit
 
The old saying is that studs provide two opportunities for removal, and not
just one as with a bolt.

Studs also allow the threads to be bottomed out. I wasn't getting enough
bolt into the aluminum intake manifold around the thermostat neck to please
me, and studs let me thread them all the way to the bottom of the hole.

But when I installed the Thorley headers in 2003, I just used the bolts
that came with them. They came out easily enough in 2008 when I repaired a
bad leak by replacing the gaskets with Remflex gaskets. Those
Thorley-supplied bolts were black-finish steel, maybe oxide. Next time,
I'll stud them and use bronze nuts, which sounds like a good strategy.

Rick "studs sometimes cause assembly interference" Denney

--
'73 230 "Jaws"
Northern Virginia
 
Maybe ARP does a made in USA stud kit for Olds. That would be nice.
--
John Lebetski
Woodstock, IL
77 Eleganza II
Source America First
 
John,

Yep, but the kit is for headers and I wonder if the studs are long enough for cast iron manifolds, probably not at 1.670" overall
length.

http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=659

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: John R. Lebetski

Maybe ARP does a made in USA stud kit for Olds. That would be nice.
--
John
 
> ...Do Not Use Grade 8 fasteners on anything exhaust.

Aww, man, now you tell me! :)
--
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
 
> > ...Do Not Use Grade 8 fasteners on anything exhaust.
>
>
> Aww, man, now you tell me! :)

Bryan,

If you installed them to no more than specified torque and if you used so much anti-seize it was dripping off when you warmed the engine up, you may
be OK.
If not, I really have to suggest that you change them out at the first convenient time.
You do not want the trouble that they can be.

Matt

--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit
 
Thanks, Matt. I torqued them to the recommended torque that Remflex recommends for their gaskets (don't recall off the top of my head what that is),
and used plenty of copper-based anti-seize goo. I really like the stud idea, though. With as many issues as I've had with leaky gaskets over the past
few years (most of them of my own doing), the stud route might be a good route to go. Knock on wood I got it right last time...except for the bolts.
:)
--
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
 
> Thanks, Matt. I torqued them to the recommended torque that Remflex recommends for their gaskets (don't recall off the top of my head what that
> is), and used plenty of copper-based anti-seize goo. I really like the stud idea, though. With as many issues as I've had with leaky gaskets over
> the past few years (most of them of my own doing), the stud route might be a good route to go. Knock on wood I got it right last time...except for
> the bolts. :)

Bryan,
As long as it is together, don't mess with it.

The Gr.8 fasteners will get you more consistent loading due to the closer production and better alloy control. And, if you only pulled them to rated
for the design fastener, when they stress relieve you will not lose much. The copper anti-sieze should prevent galling and that is all you can hope
for with any fastener.

Remflex gaskets are flexible graphite. (That is a material that I was on the leading edge of at McCord.) It has very little relaxation, but it does
have some. If you want to make the very best of it, thermal cycle it a couple of times and then pull the fasteners for tension again. You don't need
to do anything but put your torque wrench on the heads and pull. You may get a little turn at rated, but it won't be much and what you get is free
sealing load. This cannot hurt anything.

Best of luck, you have made some good choices.

Matt
--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit
 
>> Thanks, Matt. I torqued them to the recommended torque that Remflex recommends for their gaskets (don't recall off the top of my head what that
>> is), and used plenty of copper-based anti-seize goo. I really like the stud idea, though. With as many issues as I've had with leaky gaskets over
>> the past few years (most of them of my own doing), the stud route might be a good route to go. Knock on wood I got it right last time...except for
>> the bolts. :)
> Bryan,
> As long as it is together, don't mess with it.
>
> The Gr.8 fasteners will get you more consistent loading due to the closer production and better alloy control. And, if you only pulled them to rated
> for the design fastener, when they stress relieve you will not lose much. The copper anti-sieze should prevent galling and that is all you can hope
> for with any fastener.
>
> Remflex gaskets are flexible graphite. (That is a material that I was on the leading edge of at McCord.) It has very little relaxation, but it does
> have some. If you want to make the very best of it, thermal cycle it a couple of times and then pull the fasteners for tension again. You don't need
> to do anything but put your torque wrench on the heads and pull. You may get a little turn at rated, but it won't be much and what you get is free
> sealing load. This cannot hurt anything.
>
> Best of luck, you have made some good choices.
>
> Matt


I'd highly recommend a set of these under those nuts.
http://www.appliedgmc.com/prod.itml/icOid/763

The nuts are very prone to coming loose and this fixes that problem
easily, and so far permanently (25,000 miles without a peep), on my coach.

Kelvin
'73 23' in Eugene, OR
 
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