Y34/Y50 Exhaust manifold compatibility?

[cbird805]

Will a '06 M45 exhaust manifold bolt on to a '03 M45. Can it be done, or is fitment going to be an issue? I'm having trouble finding a left side exhaust manifold for my '03 M45. Dealership quoted $900 for part, plus the core charge ($150). On that note, why does it always seem to be the left side exhaust manifold that cracks on Nissan/Infiniti?

Charles Bird
2003 M45
San Luis Obispo, CA

[EdBwoy]

The manifolds' openings will mate, but you need to relocate the studs on the head.
The second part is that the flange in between the catalytic converters is off by 90 degrees, so some cutting or customizing needs to be done there.

No idea what was wrong with the original design, but they were prone to cracking, especially the left one as you noted. Neither do I know what corrections were made, but the left one was significantly more expensive than the right one from most sources when I was looking.

[szh]

Will a '06 M45 exhaust manifold bolt on to a '03 M45. Can it be done, or is fitment going to be an issue? I'm having trouble finding a left side exhaust manifold for my '03 M45. Dealership quoted $900 for part, plus the core charge ($150). On that note, why does it always seem to be the left side exhaust manifold that cracks on Nissan/Infiniti?

Interesting indeed!

I have exactly the same problem on my 2003 M45 ... it has cracked for the second or third time (in 13 years of ownership) and the dealer quoted $1450 parts and labor to replace.

In the past, I have noted that the heat from that area of the car (even when the crack was not present) has been higher than on the other side of the car from the earliest days ... must be some design or fitment flaw that causes this to occur often.

For the moment, I have decided to just wait and see if it gets much worse - my car sounds growlier than usual as a result. But, my mileage has dropped dramatically from near 15.5 mpg down to around 13 mpg. Enough of a difference that I don't know whether to simply let the car finds its way to auto-heaven rather than continue any more ... sigh.

Z

[cbird805]

I had a feeling it wasn't gonna be easy or straight forward. Thanks for the info. I guess the left exhaust manifold cracking is common to Nissan, from what was told. The 300Z/350Z VQ V6 and the VK45/VK56 V8 left exhaust manifolds cracked more often than the right. Not sure about the VR or VH series engines. I just found an OEM replacement made by Magnaflow for $425, which sound too good to be true.

[EdBwoy]

Well, go for it. Doesn't MagnaFlow offer a warranty with it? Although I'm happy that we can find aftermarket parts for our cars at their age, I'm not sure why a company would still be doing it. Unless this is some old stock?

And I didn't find it too complicated. I suppose that had something to do with the engine being outside the car when I did it . I also made them make me some custom tube including the flanges on the y-pipe and that cost a decent penny. But my justification is that if I have to replace the manifolds at any time in the future, it's that much simpler of a process to source and replace.