[1996 roadmaster]

Has anybody have had their rear exhaust manifold bolts snap? Found two broken/ missing on my motor today.

 

[jayoldschool]

Almost everyone on this forum, yes.

 

[1996 roadmaster]

At least I wasn’t left out.

 

[1996 roadmaster]

Now to find part numbers and parts. Should be fun try to find the one that has threaded stud on the top.

 

[1996 roadmaster]

Wonder if that TSB KIT still exists.

 

[1996 roadmaster]

From what I have read looks like it will be fun.

 

[shakenfake]

I welded mine out when I put on the headers.

 

[Caddylack]

Now to find part numbers and parts. Should be fun try to find the one that has threaded stud on the top.

The fancy option: https://www.summitracing.com/parts/ARP-400-1210
The budget option: Specialty Fasteners Header Bolts - Competition Products

Taken from: Current Aftermarket Exhaust Options for 91-96 GM B/D-Body

If you need the threaded studs, that is actually a common and universal part. Farm & Fleet has bins full of exhaust studs in the nuts & bolts section.

 

[Caddylack]

I will add that I had trouble with 1" bolts on my Hooker shorties. 3/4" was much better for my application.

Other headers like Clear Image have more clearance.

 

[1996 roadmaster]

Thank you

 

[96 Black]

Now to find part numbers and parts. Should be fun try to find the one that has threaded stud on the top.

Unless Caddylack corrects me he's referencing bolt lengths when installing most aftermarket headers, as those do not use the spacer collars at any locations. For your oem manifolds you simply need GR.8 1-1/2" at all places except the centerboard 2 holes each bank with no collars - for those you'll need 1". And for the alternator bracket stud you refer to, I have never heard anyone in 25 years report that one as snapping. Indeed, I personally have yet to recall any post of snapped bolts at any locations other than the rearmost 2 holes of either bank. My 'guess is those are just that extra teeny bit hotter locations against the firewall to nudge those bolts to failure.

For extracting snapped bolts there's the slik n short 1-step weld-out method shakenfake used. Just that Step 1 is: 'Get a welder'. And I've had luck with a lt. hand bit and an extractor. On one occasion the stud backed out while just using the drill. In ANY case it's important to loosen the broke part with repeated doses of heat, beating on it with nailset and PB Blaster before attempting any extractor. And on the rearmost bolt you have an extra option, and if you read that thread I'd appreciate knowing whether you can view all the pics:

Broken Exhaust Manifold Bolt

[EDIT] - 2/5/23 Most all the pics were hosted using Photobucket (which has turned into a pay site) and my attempt to replace them all using Imgur is not successful. You may (or hopefully may not) require using the 'Photobucket Embedded Fix' to view them. Here's the one for my browser, though...

www.impalassforum.com

 

[Caddylack]

Unless Caddylack corrects me he's referencing bolt lengths when installing most aftermarket headers, as those do not use the spacer collars at any locations. For your oem manifolds you simply need GR.8 1-1/2" at all places except the centerboard 2 holes each bank with no collars - for those you'll need 1".

Well, it's true that I was referring to my aftermarket headers, but...

Either way, the bolt length that is actually needed will vary from car to car. Some of the OEM studs are longer than they need to be, especially once you start deleting crap.

When buying a set of bolts, you would obviously rather be slightly too long than slightly too short, since too short won't work at all. With stock manifolds, you might consider 1" bolts instead of the 3/4" I recommended for headers.

It sounds like @1996 roadmaster understands that he will need to mix and match with studs, etc.

 

[1996 roadmaster]

Unless Caddylack corrects me he's referencing bolt lengths when installing most aftermarket headers, as those do not use the spacer collars at any locations. For your oem manifolds you simply need GR.8 1-1/2" at all places except the centerboard 2 holes each bank with no collars - for those you'll need 1". And for the alternator bracket stud you refer to, I have never heard anyone in 25 years report that one as snapping. Indeed, I personally have yet to recall any post of snapped bolts at any locations other than the rearmost 2 holes of either bank. My 'guess is those are just that extra teeny bit hotter locations against the firewall to nudge those bolts to failure.

For extracting snapped bolts there's the slik n short 1-step weld-out method shakenfake used. Just that Step 1 is: 'Get a welder'. And I've had luck with a lt. hand bit and an extractor. On one occasion the stud backed out while just using the drill. In ANY case it's important to loosen the broke part with repeated doses of heat, beating on it with nailset and PB Blaster before attempting any extractor. And on the rearmost bolt you have an extra option, and if you read that thread I'd appreciate knowing whether you can view all the pics:

Broken Exhaust Manifold Bolt

[EDIT] - 2/5/23 Most all the pics were hosted using Photobucket (which has turned into a pay site) and my attempt to replace them all using Imgur is not successful. You may (or hopefully may not) require using the 'Photobucket Embedded Fix' to view them. Here's the one for my browser, though...

www.impalassforum.com

Yes I saw the pictures I hope it doesn’t happen to me I hope there’s something left to grab onto Time will tell. My luck it’ll be flush. But I do have a mig welder.

 

[1996 roadmaster]

Thank you

 

[Z09B4U]

Now to find part numbers and parts.

From the forum a list including what could be needed if you R&R

• QTY P/N: Description Notes
• 6 10220453 Manifold to Pipe Studs 3ea. per side
• 6 11516072 Manifold to Pipe Nuts 3ea. per side
• 2 88891747 Manifold to Pipe Gaskets 1ea per side
• 60988 Felpro P/N (1/2 cost of GM)
• 2 12552469 Manifold to Head Gaskets 1ea per side
• ? 10231254 Manifold Bolt Spacers typically need 2ea +
• 1ea for each broken bolt
• 1 14037662 Manifold to Head Stud (FWD/R/H) Option
• 1 10055726 EGR Pipe Gasket to Intake Manifold Option
• 10 1.5” X 3.8”-16, Grade 8 Bolts Local Supply OR
• 10 88891769 GM Grade 8 Bolts Stock or “Resto” Guys $

TSB 44-67-03 lists adhesive 12345493 (Permatex®High TemperatureThreadlocker RED)

Should be fun try to find the one that has threaded stud on the top.

I've never seen a stud break, and never replaced a stud on my cars. I do, however, loosen and retourque the studs when I replace the bolts.

OR

If you need the threaded studs, that is actually a common and universal part. Farm & Fleet has bins full of exhaust studs in the nuts & bolts section.

OR
Get threaded rod in your choice of grade and make your own.
(If there is a reason not to do this post a correction)

When buying a set of bolts, you would obviously rather be slightly too long than slightly too short, since too short won't work at all. With stock manifolds, you might consider 1" bolts instead of the 3/4" I recommended for headers.

Some people may misinterpret this statement.

In 1994 there was a TSB 44-67-03 the block was tapped too short and the bolts would bottom out. If longer bolts are used the user should make sure there is a allowance (spacers or cut the bolt) so that the bolt used does not bottom out.

#8 or #5 Grade Bolts for Exhaust Manifold to Head?

I just replaced four of the right hand exhaust manifold bolts on my '94 Caprice 4.3 V-8 with new grade 8 bolts; I ended up re-using the first and third studs because they are very specialized (and expensive dealer only item (for '94 only)). [As detailed in my thread about O2 sensor readings in...

www.impalassforum.com

 

[Caddylack]

OR
Get threaded rod in your choice of grade and make your own.
(If there is a reason not to do this post a correction)

The reason is that you are making extra work for yourself, and it's not exactly an art project.

Is there a reason you would walk past the bin that says "exhaust studs" and buy anything else?

Some people may misinterpret this statement.

In 1994 there was a TSB 44-67-03 the block was tapped too short and the bolts would bottom out. If longer bolts are used the user should make sure there is a allowance (spacers or cut the bolt) so that the bolt used does not bottom out.

Right. What I meant was that a longer bolt can sometimes still be used with a spacer or washer. A bolt that is too short to thread will not work at all.

 

[1996 roadmaster]

The reason is that you are making extra work for yourself, and it's not exactly an art project.

Is there a reason you would walk past the bin that says "exhaust studs" and buy anything else?

Right. What I meant was that a longer bolt can sometimes still be used with a spacer or washer. A bolt that is too short to thread will not work at all.

I hope the manifolds aren’t cracked due to the two missing bolts. Where do they usually crack?

 

[1996 roadmaster]

I hope the manifolds aren’t cracked due to the two missing bolts. Where do they usually crack?

Thank you for the reference pictures and part numbers.

 

[Caddylack]

I hope the manifolds aren’t cracked due to the two missing bolts. Where do they usually crack?

You are probably fine.

When manifolds crack, it is usually somewhere near the flange where the bolts are.

The bolts/studs breaking is very common; the manifolds cracking is less common.

 

[Marky Dissod]

I hope the manifolds aren’t cracked due to the two missing bolts. Where do they usually crack?

The exhaust manifolds almost never crack.
They do have an annoying tendency to warp, though.