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Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: moparx] #3094653
11/16/22 12:29 PM
11/16/22 12:29 PM
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Morningside
AdventurerSport Offline
waaaay out there in left field
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I have a 2011 Ram 1500 in NW Iowa (rust belt) and no issues with broken exhaust bolts.
My son's 06 Jeep Commander 5.7 did break some exhaust bolts, but we got them fixed a couple of years ago and no problem since
My other son has an 06 Chrysler 300C with no broken bolts or issues

JS


76 Dodge Adventurer Sport Power Wagon W100 318, 727, NP203 Fulltime 4x4 Russet Red
06 Jeep Commander Ltd 4x4, 5.7L Hemi, QuadraDrive II
06 Chrysler 300C AWD 5.7L Hemi
10 Mopar 10 Challenger R/T, #483/500, 5.7L HEMI
11 Dodge Ram 1500 LoneStar Quad Cab, 5.7L HEMI, Fulltime 4x4, Deep Cherry Red
16 Jeep Cherokee Limited 3.2L Pentastar V6, 9 Speed Torqueflite, 4x4, Black

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: AdventurerSport] #3094675
11/16/22 01:00 PM
11/16/22 01:00 PM
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Round Lake Beach, Illinoisy
Rhinodart Offline
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Originally Posted by AdventurerSport
I have a 2011 Ram 1500 in NW Iowa (rust belt) and no issues with broken exhaust bolts.
My son's 06 Jeep Commander 5.7 did break some exhaust bolts, but we got them fixed a couple of years ago and no problem since
My other son has an 06 Chrysler 300C with no broken bolts or issues

JS


I have seen the issue more with 2013 and later 5.7's, so I am under the impression it was a change in materials... shruggy


The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!
Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: Sunroofcuda] #3094692
11/16/22 01:21 PM
11/16/22 01:21 PM
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robertop Offline
mopar
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Mmm, not really. There are many grades of stainless that can be hardened, example: most or all the trim pieces in your car.

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: Sniper] #3094693
11/16/22 01:22 PM
11/16/22 01:22 PM
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Kalispell Mt.
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HotRodDave Offline
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I don't know as though the solution is just because there is a washer there, I think it helps if the bolt is longer... think about bending a coathanger back and forth to break it, if you grab a long section and bend it back and forth a given amount like say 1 foot and bend it back and forth 1 inch it will take forever to break it, now if you grab it 1 inch apart and bend it back and forth about 1 inch it will break pretty quickly, that is what is happening on these hemis, they are short bolts being bent back and forth a certain amount that is much more than an iron manifold on an iron head would be bent, that iron manifold, iron head and long bolts because of the spacers is not really taxing the bolts enough to break them, they are not experiencing as much stress and not on such a short distance. I think a longer bolt and a spacer would reduce the stress and save the bolt even if it was the same material.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: HotRodDave] #3094698
11/16/22 01:28 PM
11/16/22 01:28 PM
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Quote

I have seen the issue more with 2013 and later 5.7's, so I am under the impression it was a change in materials... shruggy
My 2006 5.7 never broke any bolts. The manifolds did warp though.

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: HotRodDave] #3094700
11/16/22 01:32 PM
11/16/22 01:32 PM
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I would think that unless the washers were the cone shaped kind or made to absorb the expansion of the different metals the bolts would be just as likely to break but have a longer area to break in.

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: 5thAve] #3094718
11/16/22 02:47 PM
11/16/22 02:47 PM
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Kalispell Mt.
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HotRodDave Offline
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They just give a longer bolt that can take the bending stress better, those washers cone type or not don't slide around or anything, if they did they would wear out and loosen up.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: moparx] #3094743
11/16/22 03:47 PM
11/16/22 03:47 PM
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USA
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360view Offline
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Originally Posted by moparx
"Not having the end fasteners leave the aluminum cylinder at 90 degrees makes engineering sense."

being stupid, i don't understand this part. could you please explain ?
TIA. bow
beer


Sorry, I should have used more words and written more clearly in that sentence.

It should have read:

Not having the end manifold bolt fasteners thread into bolt holes in the aluminum cylinder head at 90 degree square would be an improvement.

If the end of exhaust manifold bolt holes
and their mating threaded holes in the aluminum metal of the cylinder head
were drilled and tapped at some degree of angle outward,
and the hole in the manifold made oval shaped
(or simply bigger diameter)
the thermal expansion of the exhaust manifold would not result so quickly in
the cast iron of the manifold eventually contacting the bolt threads in a “shearing” type collision
similar to how sheets of metal are ripped in two by metal shop “Shearing Machines”.

“Avoid exceeding maximum allowable shear stress levels to avoid metal failure”

is the modern advice from
3 dimensional principal stress fracture mechanics.

100 years ago engineers thought you could
pull on a bolt too much (tensile stress)
or
push on a bolt too much (compressive stress)

Today it is realized that either
“pure tensile stress“
or
“pure compressive stress”
inherently also creates SHEAR STRESSES inside materials
and importantly these internally created shear stresses
are inclined at various angles
that look “cone shaped” in 3 dimensional view.

When one of these “cones of shear stress distribution”
reaches a certain level
cracks begin growing in size
and the material eventually splits in two.

Too high a “principal” shear stress in one small region
is the “true” enemy.

Three dimensional matrix principal stress analysis
....is the scientific “slang” for this

Works for rocks as well as metals

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: 360view] #3094749
11/16/22 03:58 PM
11/16/22 03:58 PM
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HotRodDave Offline
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Originally Posted by 360view


Too high a “principal” shear stress in one small region
is the “true” enemy.






This is what I have been tryna right here.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: mopars4ever] #3094751
11/16/22 04:14 PM
11/16/22 04:14 PM
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Rittman Ohio
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Pretty sure it's just the cheapest crap fasteners they could find. Been working with alloy heads and iron manifolds for close to 40 years now and most of the Honda and Toyota cars don't do it twocents

Gus beer


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Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: fourgearsavoy] #3094754
11/16/22 04:22 PM
11/16/22 04:22 PM
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On the new dt body style ram, 19+ they added tie bars for the manifold bolts, now the manifolds are all cracking. I've replaced a ton of them, both sides

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: WV Runner] #3094766
11/16/22 04:50 PM
11/16/22 04:50 PM
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HotRodDave Offline
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Originally Posted by WV Runner
On the new dt body style ram, 19+ they added tie bars for the manifold bolts, now the manifolds are all cracking. I've replaced a ton of them, both sides


Yup. I never could sell a stock manifold till recently, now they are going like hotcakes, down to my last pair of eagle truck manifolds.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: fourgearsavoy] #3094779
11/16/22 05:23 PM
11/16/22 05:23 PM
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Originally Posted by fourgearsavoy
Pretty sure it's just the cheapest crap fasteners they could find. Been working with alloy heads and iron manifolds for close to 40 years now and most of the Honda and Toyota cars don't do it twocents

Gus beer


I don't recall the Neon's 2.0 or the K car 2.2 busting off studs, iron manifold, alloy heads

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: mopars4ever] #3094837
11/16/22 10:44 PM
11/16/22 10:44 PM
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WA
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I have a theory that it is low octane fuel , high loading like towing , steep grades or heavy throttle , causes the timing to retard and you get real hot exhaust manifolds. I would run midgrade or higher quality fuel and this problen could be mitigated .

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: WV Runner] #3094889
11/17/22 08:21 AM
11/17/22 08:21 AM
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Originally Posted by WV Runner
On the new dt body style ram, 19+ they added tie bars for the manifold bolts, now the manifolds are all cracking. I've replaced a ton of them, both sides


What he said!

If you’ve ever had the manifold off of a Nissan V8 it’s very similar to a Hemi head. Difference being they used a larger fastener in the head. Those manifolds have been cracking for years…..and the cat is integral to it $$$.

as WV said, now the Hemi manifolds are cracking. Easier than extracting broken bolts.

I’ve actually used a step drill bit and widen the end holes on the manifold side hoping that maybe it’ll prevent “shear” and perhaps the bolt will have room to bend some. I’ve also been putting a bead of copper RTV on both sides of the gasket on those end ports. I’ve seen where bolts can be broken, but no leak using that method.

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: J_BODY] #3094898
11/17/22 09:19 AM
11/17/22 09:19 AM
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North Dakota
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I hear about chronic lifter failures on the Gen III Hemi. And now exhaust manifolds. Does Chrysler have any engineers left in Engineering? shruggy


"Only the best and brightest"
Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: HotRodDave] #3094946
11/17/22 11:27 AM
11/17/22 11:27 AM
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Originally Posted by HotRodDave
They just give a longer bolt that can take the bending stress better, those washers cone type or not don't slide around or anything, if they did they would wear out and loosen up.


The cone washers do something or they'd never have bothered using them in the past. It's not a bending stress it's more a sort of tensile stress on the bolts from the manifold heating up.

Either way something isn't right with the design. I forget what make or engine it is but for one make their solution was putting in bigger softer bolts because while they were easier to break they were more forgiving to the pressures going on in the application they were being used for.

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: 5thAve] #3094961
11/17/22 12:01 PM
11/17/22 12:01 PM
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Eagle, Idaho
Neil Offline
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Install headers instead?

Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: 5thAve] #3094965
11/17/22 12:07 PM
11/17/22 12:07 PM
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Whoa-is-mia
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srt Offline
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In the early smog years the higher exhaust temps were causing bolts/studs to break. Our fix was to remove them all install new studs (with very light touch of anti sieze into the heads and then the cupped washers and bronze nuts. Check torque after a few heat cyclings and generally the carboning up and re-torque would seal them and the studs would not break.



Re: What is causing exhaust manifold bolts to break on the 5.7? [Re: HotRodDave] #3094982
11/17/22 01:14 PM
11/17/22 01:14 PM
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robertop Offline
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You are talking about a completely different type of failure here and your reasoning does not apply to this subject, sorry.

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