5.7 Exhaust Manifold Replacement

[2021QCBH]

Well, the junky manifolds finally caught up to me. Maybe a new world record for mileage? Just before flipping 110k the passenger manifold cracked right up the middle. Once it was removed you almost couldn’t see the crack.

Removal was straight forward. Wheel off/front fender liner out. Remove heat shield. The exhaust flange bolts are a bit of a pain. I did get the upper one loose and off but ended up cutting the lower with an angle die grinder. All the manifold bolts themselves broke right loose. Had to do some fancy footwork with different length sockets and extensions to get behind the shock tower etc.

Went with the BD replacement unit. Install was easy with the new hardware. The heat shield needs to be re shaped a little bit as it has its own dedicated holes that don’t use the manifold bolts like the factory unit. Manifold itself looks much more beefy and looks like a nicely finished product.

Only issue I had was getting the ball flange seal at the manifold to cat pipe sealed. Small exhaust leak there that took some beating/finesse work to get it sealed up.

I don’t think it’s leaking at all now but the exhaust seems a little louder now under lower rpm and high load (rolling into throttle without downshifting). I’m probably just fixated on it since that’s when the exhaust leak would also surface. Maybe it’s the extra flow they claim? Who knows. Hopefully the drivers side (harder side) holds out for a while.

 

[2021QCBH]

Oh also, you’ll remove a few of these to get the fender liner out. May or may not be able to reuse but mine didn’t hold tension well after removal. These are a worthy replacement for the factory pieces.

https://www.amazon.com/dp/B0B1WWWZNF?ref_=ppx_hzod_title_mob_b_fed_asin_title_0_0

 

[silver billet]

Well, the junky manifolds finally caught up to me. Maybe a new world record for mileage? Just before flipping 110k the passenger manifold cracked right up the middle. Once it was removed you almost couldn’t see the crack.

Removal was straight forward. Wheel off/front fender liner out. Remove heat shield. The exhaust flange bolts are a bit of a pain. I did get the upper one loose and off but ended up cutting the lower with an angle die grinder. All the manifold bolts themselves broke right loose. Had to do some fancy footwork with different length sockets and extensions to get behind the shock tower etc.

Went with the BD replacement unit. Install was easy with the new hardware. The heat shield needs to be re shaped a little bit as it has its own dedicated holes that don’t use the manifold bolts like the factory unit. Manifold itself looks much more beefy and looks like a nicely finished product.

Only issue I had was getting the ball flange seal at the manifold to cat pipe sealed. Small exhaust leak there that took some beating/finesse work to get it sealed up.

I don’t think it’s leaking at all now but the exhaust seems a little louder now under lower rpm and high load (rolling into throttle without downshifting). I’m probably just fixated on it since that’s when the exhaust leak would also surface. Maybe it’s the extra flow they claim? Who knows. Hopefully the drivers side (harder side) holds out for a while.

I thought I noticed a little more throaty sound , got both done at the same time when the driver side cracked on me.

 

[2021QCBH]

It just sounds more ticky under high load. No different at all for the actual exhaust note or any other operating conditions. Maybe a little more ticky externally on high idle cold starts on that side.

I’d have done both but I was time limited with my current schedule for the next couple months.

How many miles on yours now ?

 

[silver billet]

It just sounds more ticky under high load. No different at all for the actual exhaust note or any other operating conditions. Maybe a little more ticky externally on high idle cold starts on that side.

I’d have done both but I was time limited with my current schedule for the next couple months.

How many miles on yours now ?

Mine didn't sound ticky at all, just a little richer though I could definitely be wrong.

I have about 30k kms on them at this point.

 

[2021QCBH]

Not sure how much guys have experience with higher performance stuff here but to me the new manifold sounds more like a car with headers. The header is thin walled and lets more of the tinny sounding exhaust noises escape. Going to chalk it up as the metal composition being different/harder I guess.

Went about 650 miles this weekend with no change in the noise. That side of the truck was always louder at high idle but not noticeable in the cab.

I’m picky to put it best. Guess I’ll live with it and do the same replacement when it comes time to do the drivers side then I’ll know if it changes there too.