Guys, I had my flex pipe changed out the other day, and was informed by the welder/muffler shop that my exhaust manifold is also cracked. The flex was as well and replaced. I didnt do anything at that moment with the reported cracked manifold. I need to pass california smog and I am throwing 0420, which I am hoping is just a result of the excess air thru leak. California cats are a lot more expensive than anywhere else where brains exist.

Question for the experts here...I havent really looked hard, but wondering if the ones with experience can tell me if i can diy the manifold from the top after unbolting flex pipe,,,or does it have to come out thru the bottom as I was informed by muffler shop. If I can do it from the top, I am ore inclined to diy. If its bottom only, I personally dont like crawling under a jacked up car on stands. sorry, it freaks me out.

 

Come out the top, used ones are cheap. Check the torque specs thread the nuts a not very tight.

 

EASY PEASY. Like alot of 4 cylinders, once that huge airbox is out of the way pretty much anything is accessible back there. They might not have thought about removing the air box. Who knows. Its a pretty small manifold. When we were working on my dads truck his exhaust manifolds were the size of my engine LOL

 

Yes, according to this , the P0420 code could be from the cracked exhaust manifold.

https://www.obd-codes.com/p0420


I still have my spare one in the shed, I bought it from Donbrew years ago, so far it warded off the evil

 

Same situation here, replaced flex to find the manifold cracked. $149 for the part and 1.5 hours book time to r&r. My total was $318.50 out the door.
I believe the stress is caused by failed motor/trans mounts coupled with the factory "flex" which from what I saw was nothing more than a semi corrugated section of 16 gauge pipe, not very flexible.

 

I have a spare manifold in inventory, just for such an emergency.
Ive had the flex pipe fail on the OEM down pipe , but not the replacement down pipe.
My P0420 code was the flex pipe cracked

 

That does not look like it was leaking; could that just be a mold flaw?
However the crack by the stud hole is different.

 

Its definitely cracked. Its nice and quiet now. I saw that crack at the stud hole also but wasnt sure if it was a relief cut or not.

 

Heres a close up

 

There is a relief cut between 2 & 3 that looks like a crack, but it goes all the way up and through.