Replacing exhaust manifolds with a 'like' OEM replacment

from the consensus on this forum, they all will fail. just a cheaper version than OEM.
if you need to sell the truck and need a quick fix, buy good used or cheap new. if you are keeping the truck for a few more years, headers, B pipes, and tune from Cajun are the best way to go...

+1 for the amount of labor involved you don't want to do this job twice.. OE replacements WILL fail.

I see. So, the problem is in the design, not the oem parts themselves?

pdxrealtor said:

I see. So, the problem is in the design, not the oem parts themselves?

Click to expand...

seems the oem`s have a failure around 80k+, maybe the aftermarkets are`nt built as sturdy. I have not come across reading here a time line on the aftermarkets. in most cases probably outlast the ownership of the truck.

and from what I gather, older models seem more problematic than new...

what is different with the newer mani`s, I`m not sure, and someone has reported a different part number...

who knows, mine could have l;asted as long as I plan on keeping the truck. I just had a different mission...

so there are good used one out here, just choose a later model year than older...

It's odd to me that the OEM parts fail, and the OEM copies fail. But the JBA with welded cats seem to be a recommended, solid, option.

I'm asking these questions because I'm about to buy a truck that had the manifolds replaced with OEM copies. Because it's done already I have no problems with them being on the truck as long as it was in fact a legitimate replacement option.

I was under the impression there was no option but OEM (factory Nissan) or aftermarket non-OEM style replacements. The option of aftermarket OEM style replacements is new news to me.

pdxrealtor said:

It's odd to me that the OEM parts fail, and the OEM copies fail. But the JBA with welded cats seem to be a recommended, solid, option.

I'm asking these questions because I'm about to buy a truck that had the manifolds replaced with OEM copies. Because it's done already I have no problems with them being on the truck as long as it was in fact a legitimate replacement option.

I was under the impression there was no option but OEM (factory Nissan) or aftermarket non-OEM style replacements. The option of aftermarket OEM style replacements is new news to me.

Click to expand...

well its like anything else, how many different brands of oil filters are there, some do a good job, some do a better job, and some are super cheap and the owner doesnt care about start up noise or collapsing filter elements.

now with the mani`s in your case, they could last a long time or not... what is the warranty on the truck?

Theres obviously a design flaw if the nissan oem replacement fail, and the aftermarket oem copies fail in the same way. No?

The truck I'm buying is a used 2004 (private party) with 150k on it. So, to answer your question no warranty.

pdxrealtor said:

Theres obviously a design flaw if the nissan oem replacement fail, and the aftermarket oem copies fail in the same way. No?

The truck I'm buying is a used 2004 (private party) with 150k on it. So, to answer your question no warranty.

Click to expand...

I wouldn`t think Nissan had intended the oem`s to fail, it was just a matter of time before they started to see repeated failures. there was a change made, maybe a support or redesigned flange.

it would be my guess that the tubing wall thickness is thin, high heat fracturing the tubing. Exhaust parts are subjected to a lot of frequencies, vibrations and movement, plus a ton of heat/cold cycles. over time they become weaker then the infamous exhaust tick/leak occurs.

so like any cheap aftermarket part to get you by, they have their limits as well.

I've seen OEM replacements (dorman etc) fail in a little as a few months, but they could last for the life of the truck, who knows.

pdxrealtor said:

It's odd to me that the OEM parts fail, and the OEM copies fail. But the JBA with welded cats seem to be a recommended, solid, option.<snip>

Click to expand...

To make sure you're clear, the JBA short tube headers with welded cats is not the generally preferred option. The recommended option is long tube headers - JBA or other - and replacement b-pipes that include high-flow cats. There is some benefit in reliability moving the cats well back from the engine, I believe.

The new b-pipes bolt to the LT header and cat-back exhaust flanges (ie, no welding needed to install).

The only time the shorties seem to be needed is for the California guys, to pass their emissions check, and in that case the cats do need to be welded to the headers during install.

Some folks in states with lesser emissions checks can even get by with non-catted b-pipes which only include a resonator. (yes, I'm jealous...).

Hope that clarifies.

dreep said:

To make sure you're clear, the JBA short tube headers with welded cats is not the generally preferred option. The recommended option is long tube headers - JBA or other - and replacement b-pipes that include high-flow cats. There is some benefit in reliability moving the cats well back from the engine, I believe.

The new b-pipes bolt to the LT header and cat-back exhaust flanges (ie, no welding needed to install).

The only time the shorties seem to be needed is for the California guys, to pass their emissions check, and in that case the cats do need to be welded to the headers during install.

Some folks in states with lesser emissions checks can even get by with non-catted b-pipes which only include a resonator. (yes, I'm jealous...).

Hope that clarifies.

Click to expand...

yes, when the cats are close to the exhaust mani: a dying cat breaking up gets sucked back into the engine during reversion. the material is highly abrasive and kills the cylinder walls.

it`s now beer:30 :big_grin:

Please do yourself a favor and stay away from any make manifolds or shorty with welded cats. The design is the issue and second failure is likely. The labor is something you only want once trust me. Feel free to call me with any questions on the best fix and bang for your buck on the market Cajun Stage 1. My cell is listed on the website Cajun Bpipes | shreveport, LA 71129

As I said above the truck I'm buying has new OEM copy headers with cats. If they fail when I own the truck you're the guy I'll call.