New: Exhaust question '03 M45 w/ 65k

[Houndstooth]

I'd like to put up a more formal introduction, but I'm tight on time and leaving for a 3hr trip tomorrow. I just purchased this car last week and by all appearances it's a lovely, diaper wiped 65k mile example. Two days ago I noticed some crackling of sorts reverberating off concrete walls or what have you when driving by. Further, if I apply the brakes with the accelerator I can intensify the noise at low speeds. It did coincide with me purchasing gasoline from a mom and pop's gas station so I hoped bad gas was the cause (not that I've actually ever experienced this in a car prior). Subsequently, I added some Shell Nitro hoping for a resolution and have had none.

My summation: it sure seems like this is either a cracked manifold or manifold gasket. Will this typically throw a code (of which there is none currently)?

[EdBwoy]

It's alright, we receive people coming in hot all the time.

Yes a code could follow an exhaust leak if it were before the secondary O2 sensor; and if I were a betting man, I'd say the left exhaust manifold is the more likely culprit for a crack.

Come to think of it, noone that posted about cracked manifolds here and in the q45 forum mentioned any codes.
I think a physical observation would be the best way to verify this.


... or yeah, just bad gas that needs to be worked out. The kind of sound I get when I've run seafoam.

[Houndstooth]

Thanks for the left-side directive. It's going on a lift Monday with the aim of zeroing in on the problem. Curious. When under heavy/full acceleration it returns to smooth silence. I'm assuming under pressure the flow is simply channelling to where there's the least resistance.

[szh]

Yes a code could follow an exhaust leak if it were before the secondary O2 sensor; and if I were a betting man, I'd say the left exhaust manifold is the more likely culprit for a crack.

Come to think of it, noone that posted about cracked manifolds here and in the q45 forum mentioned any codes.

Yeah, the left exhaust manifold has gone out twice on my 2003 M45 ... right now, it is out for example, and I don't feel like spending the $1500 to get it fixed. Sigh ... need to do it soon though.

No codes however.

Z

[EdBwoy]

Z, thanks for clarifying that part. I suppose the crack location means that the flow between the first and second sensor is unaltered. Sensor 1 will read slightly different from the right side, but sensor 2 says everything looks OK here... hence no codes.

Btw, when I replaced my engine I decided to use exhaust manifolds from a 2006+ M45. They mate up nicely at the heads, but the flange between the cats has to be rotated 90 degrees... that and I had to "massage" the exhaust shield to play nicely with the steering shaft. - just another option; because you might end up spending less for a used 06+ manifold + labor versus a new y34 one.


To build on OP's question, I suggested he focus on the right hand side resonator as , as discussed herein:
y34-factory-exhaust-cutout-no-way-dual- ... 03328.html

[Houndstooth]

Yes a code could follow an exhaust leak if it were before the secondary O2 sensor; and if I were a betting man, I'd say the left exhaust manifold is the more likely culprit for a crack.

Come to think of it, noone that posted about cracked manifolds here and in the q45 forum mentioned any codes.

Yeah, the left exhaust manifold has gone out twice on my 2003 M45 ... right now, it is out for example, and I don't feel like spending the $1500 to get it fixed. Sigh ... need to do it soon though.

No codes however.

Z

Thanks, szh. Per Ed's mention and aside direction I'm focused on the right side resonator at present. I had an exhaust fabricator put her on a lift and he went around the manifolds with a stethoscope and couldn't hear any leak. Subsequently, I took a vid I'll post below and redirected my attentions. Going to try a right side resonator delete on Friday and see where I'm at. Putting our heads together we concluded this may be from moisture rot due to the low mileage and infrequent use.

https://www.flickr.com/photos/142356812 ... ed-public/

[Houndstooth]

All smiles here after my exhaust appointment today. The fabricator had her on a lift Monday and banged around at it without any tell-tale rattle, but upon reinvestigation today we isolated where it was coming from. Or thought it was the culprit anyway. Then when it hit the floor of the shop it was solid. Rapping on the floor prompted no rattles at which point I began to regret the removal. Regardless, we carried on and installed a pipe to replace it. Voila! That was it. Tonally not much has changed though there is a tad more growl to her when opened up. Thanks, Ed!

https://flic.kr/p/XMexkf

https://flic.kr/p/XD6Y5z

https://flic.kr/p/XD71fg