Hemi Exhaust Manifold bolts

[Chanyote66]

Here is some insight on the problem from an engineering standpoint,

The aluminum heads expand and contract at almost exactly double the thermal expansion coefficient of iron.
If they overbuilt the manifolds, which if you have battled getting one out, you would know it is heavy and overbuilt, Then the flange area is too rigid to flex to the expansion and contraction of the head. Many other cars and trucks that still use Iron manifolds with aluminum heads, but if their manifolds are thinner and more flexible, they can handle the expansion better.

The big reason that the headers do not have this issue is that it is tubes welded to a flat plate, the flat plate can flex and expand/contract better with the engine than what a large 3 dimensional monolithic iron chunk can.

some reference points:
Thermal expansion (fractional expansion per degree C x10^-6)
Aluminum 24
Iron 12
Steel 13

In regards to the warranty work, How much do you value your time? If you have to spend a few hours a year driving to, waiting at, and returning from the dealership, that a lot of wasted time, Surely more than $600 of your time wasted "fixing an issue" the exact same way it broke last time. Just go get headers and install them, if you tow, get the little bit of gains from the shorty's and stop driving to the dealership all the Damn time!

 

[silver64]

Here is some insight on the problem from an engineering standpoint,

The aluminum heads expand and contract at almost exactly double the thermal expansion coefficient of iron.
If they overbuilt the manifolds, which if you have battled getting one out, you would know it is heavy and overbuilt, Then the flange area is too rigid to flex to the expansion and contraction of the head. Many other cars and trucks that still use Iron manifolds with aluminum heads, but if their manifolds are thinner and more flexible, they can handle the expansion better.

The big reason that the headers do not have this issue is that it is tubes welded to a flat plate, the flat plate can flex and expand/contract better with the engine than what a large 3 dimensional monolithic iron chunk can.

some reference points:
Thermal expansion (fractional expansion per degree C x10^-6)
Aluminum 24
Iron 12
Steel 13

In regards to the warranty work, How much do you value your time? If you have to spend a few hours a year driving to, waiting at, and returning from the dealership, that a lot of wasted time, Surely more than $600 of your time wasted "fixing an issue" the exact same way it broke last time. Just go get headers and install them, if you tow, get the little bit of gains from the shorty's and stop driving to the dealership all the Damn time!

So why don't manufacturers use aluminum headers instead of manifolds? Part of it is cost and part of it is longevity. Cast Iron lasts a lot longer than aluminum and then there's the fact that adding headers to an otherwise stock exhaust system is not going to make a bit of difference other than increasing costs over a manifold. In fact for performance hobbyists, adding headers is usually a last step after other optimizations on the exhaust system to reduce backflow pressure.

 

[jabara572]

So why don't manufacturers use aluminum headers instead of manifolds? Part of it is cost and part of it is longevity. Cast Iron lasts a lot longer than aluminum and then there's the fact that adding headers to an otherwise stock exhaust system is not going to make a bit of difference other than increasing costs over a manifold. In fact for performance hobbyists, adding headers is usually a last step after other optimizations on the exhaust system to reduce backflow pressure.

Way too hot for aluminum to survive long term without extensive engineering and cooling. Headers can get north of 1200 degrees run hard. They arent big chunks of alumium like your heads (also water cooled), they will melt or fail.

 

[Rsgli]

I feel the issue is caused by the MDS.. as it shuts down cylinders that difference in temperature in cylinders hot/cooler will cause the manifold to warp over time. This will causes the bolts to snap and exhaust leak. I traded my 17 on a 20 so I’m going to test my theory by selecting manual shift so MDS not activate to see if I have any issues!

 

[Hereford]

Going to be taking mine in this week for what I believe is leaking exhaust manifold. Irritating that this new of a truck is doing it. Every hemi I have had has done this.

 

[User_3336]

MDS OFF, every time I drive.

 

[Nails]

I don’t disagree on mds part. I just don’t think its enough to do this on its own.

This is in simple, in simple form— 2 different metals heating and cool at 2 different rates with out expansion/contraction reliefs. That’s it...

 

[Hereford]

Ended up being a cracked manifold!! There are some strips or bracing that the tech said they added on the 19's+ that the bolts go through that are meant to help alleviate the bolts breaking. Not sure how it would make a difference but that's what he said. Hopefully the new manifold will last the life of the truck but kinda worried now.

 

[Nails]

I have yet to tear a 5thgen down to see though strips and braces the tech speaks of. I’ve read a few that have swapped out manifolds/headers and no speak of those

 

[Hereford]

I have yet to tear a 5thgen down to see though strips and braces the tech speaks of. I’ve read a few that have swapped out manifolds/headers and no speak of those

He showed them to me but heck if I can see if they could do anything to help. I have worked alot on farm trucks and tractors and never seen anything like this. Evidently the manifold is different on these 5th gens as all of our past hemi engines never had cracks etc just gaskets and broke bolts.

 

[Nails]

Correct 5th gens are different manifolds then previous gens. Just makes me more curious

 

[Chance]

Ended up being a cracked manifold!! There are some strips or bracing that the tech said they added on the 19's+ that the bolts go through that are meant to help alleviate the bolts breaking. Not sure how it would make a difference but that's what he said. Hopefully the new manifold will last the life of the truck but kinda worried now.

I Also have a cracked manifold. Only 62k miles. I dropped it off at dealer today for a creak in steering, tech called me this afternoon and said i also have a cracked manifold. He also mentioned the strips that are there to prevent bolts breaking.

 

[Nails]

Humm, the Q is now out.... take broken manifold over broken in head manifold bolts...

 

[Hereford]

I love my ram trucks and would still purchase again hands down but it is crazy that they cannot get a true fix to the manifold issue whether it's the bolts, gasket, or manifold itself. The 5.7 hemi design is old as the hills and should be fined tuned by the engineers by this point. If it happens again its probably just going to stay cracked or I will weld it. Truck sounded like crap until fixed. Hopefully it was a flaw in the cast that left it vulnerable to cracking.

 

[Nails]

Nature of the 2 different metal beast. Stainless grade manifold or cuts in flange for flex would be the answer to it.

 

[Orion10182011]

Way too hot for aluminum to survive long term without extensive engineering and cooling. Headers can get north of 1200 degrees run hard. They arent big chunks of alumium like your heads (also water cooled), they will melt or fail.

You would think, but there are engines with the exhaust headers cast into the heads these days. For example the 3.2 Pentastar and the Honda 1.8L I4 both have cast in E manifolds.

Also Manufactures have been using AL heads with cast Iron exhaust manifolds for decades. There is no reason Ram can't fix this. I wish ARP would release a set of direct replacement bolts.

 

[Chanyote66]

Also Manufactures have been using AL heads with cast Iron exhaust manifolds for decades.

3.6 pentastar also has cast heads/headers my wifes 2014 JK has this.

 

[Americantruck04]

I feel the issue is caused by the MDS.. as it shuts down cylinders that difference in temperature in cylinders hot/cooler will cause the manifold to warp over time. This will causes the bolts to snap and exhaust leak. I traded my 17 on a 20 so I’m going to test my theory by selecting manual shift so MDS not activate to see if I have any issues!

I doubt it cause my dad has a 2004 hemi And they broke on his too

 

[INVISBLE]

Well I have a 2020 limited with the etorque Hemi and I just started to develop an exhaust leak that for now goes away after about 2 minutes of idle. Got an appt with the dealer in 2 weeks(they claim to be behind) to drop it off for a week(dealer claims its a couple day job if it's the bolts, less if manifold) so I will let you know how that goes... 16k miles

 

[RAMSTER@]

So I talked with a number of mechanics at different places on this issue - it seems like it's typically the passenger side and the bolt that's the furthest back towards the firewall. It's the double bolt that holds the heat shield. One mechanic said he's been able to get to and remove the broken bolt without removing the exhaust manifold. It typically breaks right at the bolt head - he extracts the stud with a chisel and then replaces the bad bolt. This is exactly what happened to my 2019 Ram. Slight exhaust leak on passenger side - quieted up after a few minutes of running. The broken bolt was loose in the head, but I couldn't get it to turn so I pulled the manifold. An exhaust shop could have easily welded a nut onto the broken part for removal.

The Driver's side manifold is pretty easy to do - jack up the pass side, remove front tire, pull the inner plastic fender well liner, and it's all right there. You'll need 13mm and 10mm deep well sockets for the 3/8 drive and 9/16 for the collector bolts. Remove the 4 heat shield bolts and pull that out of the way. I went after the 9/16 bolts on the collector after that. Use a little penetrating lube on the bolts and they should back out pretty easily - I used 3x long extensions to access bolts from under the truck. I then went after the manifold bolts - you can put a socket on all but the upper right 13mm - that one you need to go with a box end wrench. A few of the bolts were pretty loose. Once all the bolts are out I got the gasket and cleaned up the port that had the leak with a wire brush. You can slide the manifold all the way to the front of the engine compartment - not sure if it can be removed. I used the Dorman bolt kit 03309 that was in stock at O'reilly for the re-install.

I re installed the gasket w manifold and followed the torque sequence (there is a sequence for the manifold) and it only calls for 20 lbs on the bolts. I should have used some thread lock on the 10mm bolts, but didn't. The 13mm bolts already had thread lock on the bolts. I buttoned everything else back up and went on my merry way. Really isn't rocket science.

It was about 2 hrs total + calling/running around for the bolt kit. Make sure you have 10mm and 13mm deep well sockets for the 3/8 drive. The dealership quoted $970 for one side - kind of a joke if you ask me for a 2 hr. job and a $40 bolt kit. As far as warranty goes, my 2019 was good up to 60k on the manifold bolts. I'm at 75k so way past the extension on the bolt warranty.