Exhaust manifold

[TonyW]

Hello all, first time user. I have a 2019 Ram 2500 6.4 Hemi. Both of my exhaust manifolds are warped and leak. According to my mechanic, they are still in decent shape and recommends not replacing yet. My concern is that when I finally do replace them, they will be replaced with OEM manifolds. Does anyone know of aftermarket manifolds that are a better option and last longer? My mechanic said that, in his experience, once you replace them, you are doing it about every two years or so. Any advice is greatly appreciated.

 

[G-Ride990]

If you replace them with new OEM parts, they are going to do the same thing.

If you, "plane" the stock manifolds back to being flat and use new hardware, you will not have the same issue again.

BD makes aftermarket parts that are supposed to be better that don't have this issue.

This is a commonly debated issue here.

You really need to do some research to figure out what the best option is for you.

EXHAUST MANIFOLD KIT RAM 5.7L HEMI: 1500 DS 09-24 / 2500-3500 09-18

Experience unparalleled performance and durability with our enhanced Dodge/RAM truck exhaust manifolds, specifically designed for 5.7L HEMI engines. Our BD upgraded manifolds address common exhaust manifold bolt failures by incorporating extended fasteners and spacers that effectively withstand...

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[HEMIMANN]

Hello all, first time user. I have a 2019 Ram 2500 6.4 Hemi. Both of my exhaust manifolds are warped and leak. According to my mechanic, they are still in decent shape and recommends not replacing yet. My concern is that when I finally do replace them, they will be replaced with OEM manifolds. Does anyone know of aftermarket manifolds that are a better option and last longer? My mechanic said that, in his experience, once you replace them, you are doing it about every two years or so. Any advice is greatly appreciated.

There are no aftermarket manifolds for the 6.4L Hemi. I just went through this last winter.

The left bank manifold has a welded EGR tap pipe in it. 5.7 Hemis don't have this. No aftermarket supplier wants to make this funky manifold for the low sales volumes of the 6.4L Hemi.

Get 'em planed flat like I did.

 

[TonyW]

I have looked into BD, unfortunately, they don’t make the manifolds yet for the 6.4 gas engines. They only make them for the 6.7 diesel.

 

[HEMIMANN]

I have looked into BD, unfortunately, they don’t make the manifolds yet for the 6.4 gas engines. They only make them for the 6.7 diesel.

No, they make them for the 5.7 HEMI also. But NOT the 6.4 HEMI

 

[Daw14]

A belt sander can be used to get them flat again. The sooner the are removed the less broken fasteners to deal with .

If you get broken fasteners , they are best removed by welding a nut to the stub . Drilling them out has resulted in many people drilling into the water jacket in the head causing coolant leaks.

 

[dieselscout80]

If you replace them with new OEM parts, they are going to do the same thing.

If you, "plane" the stock manifolds back to being flat and use new hardware, you will have the same issue again.

BD makes aftermarket parts that are supposed to be better that don't have this issue.

This is a commonly debated issue here.

You really need to do some research to figure out what the best option is for you.

EXHAUST MANIFOLD KIT RAM 5.7L HEMI: 1500 DS 09-24 / 2500-3500 09-18

Experience unparalleled performance and durability with our enhanced Dodge/RAM truck exhaust manifolds, specifically designed for 5.7L HEMI engines. Our BD upgraded manifolds address common exhaust manifold bolt failures by incorporating extended fasteners and spacers that effectively withstand...

us.bddiesel.com

I wouldn’t think if they were sanded/ground flat that the would warp again.

 

[jws123]

If you replace them with new OEM parts, they are going to do the same thing.

If you, "plane" the stock manifolds back to being flat and use new hardware, you will have the same issue again.

BD makes aftermarket parts that are supposed to be better that don't have this issue.

This is a commonly debated issue here.

You really need to do some research to figure out what the best option is for you.

EXHAUST MANIFOLD KIT RAM 5.7L HEMI: 1500 DS 09-24 / 2500-3500 09-18

Experience unparalleled performance and durability with our enhanced Dodge/RAM truck exhaust manifolds, specifically designed for 5.7L HEMI engines. Our BD upgraded manifolds address common exhaust manifold bolt failures by incorporating extended fasteners and spacers that effectively withstand...

us.bddiesel.com

Once these manifolds are sanded flat after warping they do not re warp.

 

[RamCatMan]

Once these manifolds are sanded flat after warping they do not re warp.

I second that, they shouldn’t warp again if you’ve been driving it like that for a few months. After removing both manifolds from my 5.7 and rubbing out +.050” of rock in em I haven’t had any issues. I didn’t have access to a mill to fly cut them at the time so I did it against my belt sander, being careful to apply even pressure. I couldn’t slip more than a .003” shim between the manifolds and my granite counter top so I called it done. With all the heat cycles or annealing they’ve been through I imagine any internal stress has been relieved from the material, and after two years I haven’t had any issues

 

[Daw14]

I wouldn’t think if they were sanded/ground flat that the would warp again.

They have been heat cycled enough , they will retain the current shape . No more warping.

 

[HEMIMANN]

Exactly right. They warp to stress relieve themselves, since the factory won't - it costs too much.

They've since tried a redesign that reportedly breaks itself instead of the bolts.

 

[rpr]

Hilarious…and I bet there’s an engineer somewhere in the depths of Chrysler who’s proud that he was able to find a solution to the bolts breaking.

 

[HEMIMANN]

If you look at BD Diesel's design, you'll see why nothing breaks.

Guess what? It costs more! What a surprise.
Too bad they don't make a set for 6.4 Hemi. Oh well - the old ones had to come off anyway, and I finally found a shop to plane them flat. Still nice and quiet. Plus they fit!

 

[rpr]

Any recommendations on the type of shop to look for to plane them? I’m going to have to do this soon.

 

[foxtail]

Any machine shop should be able to do it for you. Did mine last year as well. Planned both flat for 60 Canadian bucks. Dorman rockauto wants 130 a piece new. So much less getting them planned. For me anyways...

 

[HEMIMANN]

Members that aren't all crippled up like me have or rent a belt sander and check flatness with a straight edge ruler.

I would've done that if 20-25 years younger. I asked the shop I use that does the manifold replacement if they knew of a local machine shop, and they did - having done a bunch of Ram manifold replacements over the years. Start with your local indie shop.

 

[HEMIMANN]

Any machine shop should be able to do it for you. Did mine last year as well. Planned both flat for 60 Canadian bucks. Dorman rockauto wants 130 a piece new. So much less getting them planned. For me anyways...

Doesn't matter what they cost new - they new ones will warp. That's not a fix.

 

[RamCatMan]

It’s definitely an unfortunate situation but not isolated to just Chrysler. I’ve heard the same problem happens with other modern V8 manifolds but the funny thing is when I was a kid this even happened on my folks 4 banger Mazda protege, except the manifold actually cracked. That was the loudest car I’d heard in the first 8 years of my life!
Someone here did mention aftermarket manifolds which are supposed to be thicker or have more gussets cast into them, I think the material around the thru-hole where the bolts go is actually taller or they have some crazy thick washers between the manifold and the head of the bolt, so naturally those require longer bolts like you see on some diesel engines. Because a longer bolt can stretch further before breaking, the manifold can expand, warp, etc before popping the heads off the bolts, it’s actually a really good concept. If you’re leaning towards something like that it may be worth asking them what kind of heat treatment, testing, and service life to expect. Also, there’s a 99.9% chance you’ll already have to buy new hardware because a few of the manifold bolts will be broken ..I think someone was suggesting not to reuse the old ones, that is VERY good advice…replace all of the old bolts. After I got the flatness back in em I reinstalled the original manifolds with new Mopar heat shields and gaskets, and new Dorman stainless hardware.

 

[Dusty]

"Someone here did mention aftermarket manifolds which are supposed to be thicker or have more gussets cast into them, I think the material around the thru-hole where the bolts go is actually taller or they have some crazy thick washers between the manifold and the head of the bolt, so naturally those require longer bolts like you see on some diesel engines. Because a longer bolt can stretch further before breaking, the manifold can expand, warp, etc before popping the heads off the bolts, it’s actually a really good concept."

Exhaust manifolds have always warped. Compare the gusset thickness of the newer manifolds to those of the sixties and you'll see why problems with exhaust manifolds, especially broken bolts, were fairly rare.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 134554 miles.

 

[Crazydragn64]

BD Diesel