[wolfpack17]

Hi all,

I recently had the following services performed on my N26 '13 328i xDrive (127k mileage):

Spark plug change
Coolant fluid flush
Transmission fluid flush
Brake fluid flush
Oil change

I left my mechanic and was impressed by the throttle response with new plugs and thought everything was A-ok. Got into my parking garage and am noticing a metallic-sounding click/tick towards the exhaust that I cannot hear with my windows rolled up. I figured this would have been an issue from changing the plugs, but I do not hear the noise inside of the engine bay at all, only from the rear of the vehicle.

I've linked a video at the bottom of this post. Any ideas on what this might be? I live about 50 mi away from my mechanic, unfortunately, so wondering if it's safe to drive it back to the shop. The drive home was really smooth.

Thank you in advance for any advice/help!

[shiftdnb]

Did you look under the car and see if you can pinpoint where the noise is coming from or is that noise seem like it's coming out of the exhaust? Kind of sounds like something is either too loose or too tight under the rear of the ar causing a metal to metal contact with the vibration

[wolfpack17]

I did look and didn’t see much frankly. It seems more like it is coming out of the exhaust itself

[Psi5]

Could be a bracket or loose connection. Alternatively, and sorry to have to suggest this, that's the same noise my E39 started making at about 140K miles when the cats started going bad. They break down internally and the pieces rattle around. Priced out replacements and, at the time, they were $1500/each times two plus install. Ooof...

Hope it is a bracket or clamp.

[njdangelo]

yikes. kind of sounds like a failed catalytic convertor. I'd bring it right back to them to make sure its not something they worked on. A broken cat would definitely give you better throttle response though lol and yes its safe to drive back to them.

If it is the cat it would be cheaper to throw in a highflow catted downpipe then to replace with OEM. This will also give you better throttle response and should not cause any check engine lights. I have had really good results with mine from CTS

[wolfpack17]

Thanks for the suggestions! Hoping it's not a cat either; there's a reason those tend to get stolen $$$

Will be taking it back to the shop and having them take a look later this week. Mechanic suggested that it may be an exhaust valve issue, and based on a video I found, it sounds pretty similar. One reason my video sounds a bit more extreme is an echo from being backed up into the corner in my garage. When I am in open space, with the windows down, it sounds about like this from the driver seat (see 1:43).

Will keep you all updated!

[thejeremyman9]

I've had the exhaust rattle from the fixing bow and it sounds totally different than what you posted in OP, and its also very obvious if its the fixing bow if you listen from the rear of the car.

[wolfpack17]

Originally Posted by njdangelo

yikes. kind of sounds like a failed catalytic convertor. I'd bring it right back to them to make sure its not something they worked on. A broken cat would definitely give you better throttle response though lol and yes its safe to drive back to them.

If it is the cat it would be cheaper to throw in a highflow catted downpipe then to replace with OEM. This will also give you better throttle response and should not cause any check engine lights. I have had really good results with mine from CTS

Would this be economical with an N26? Most I see on this mod is for N20s

[thejeremyman9]

Originally Posted by wolfpack17

Would this be economical with an N26? Most I see on this mod is for N20s

Aftermarket DP is a great power mod in general, but i will note that most catted DPs will throw a CEL and will not pass emissions, so don't just purchase one assuming you will be fine in that respect. Not sure for N20/26, but for N55s, you will pay ~$1000+ for a DP that is guaranteed to not throw a CEL and get your emission monitor ready, especially with recent price increases.

[im_an_alien]

Was this sound present before the service was done? It's clearly hard to miss... coincidence?

[wolfpack17]

Originally Posted by im_an_alien

Was this sound present before the service was done? It's clearly hard to miss... coincidence?

No, it was not present before the service. That said, I did get it all the way home before noticing because I could only hear it with the windows down/from outside of the car.

Maybe something was not tightened properly/disconnected and revealed itself on the drive home? Hard to know, but I will update with the culprit once they reinspect

[wolfpack17]

Originally Posted by thejeremyman9

Aftermarket DP is a great power mod in general, but i will note that most catted DPs will throw a CEL and will not pass emissions, so don't just purchase one assuming you will be fine in that respect. Not sure for N20/26, but for N55s, you will pay ~$1000+ for a DP that is guaranteed to not throw a CEL and get your emission monitor ready, especially with recent price increases.

Well, hopefully, I won't have to cross that bridge but thanks for caution. This car is stock, so I definitely don't have a clue what I'm doing there. But, even if a good one is the same price as a cat, and I get more power out of it, could be a consolation prize for the trouble.

[wolfpack17]

As an update, my mechanic found that a spring between my exhaust valve actuator and the exhaust flap was missing.

It must have come ajar on the ride home... easy fix, phew

[Psi5]

Originally Posted by wolfpack17

As an update, my mechanic found that a spring between my exhaust valve actuator and the exhaust flap was missing.

It must have come ajar on the ride home... easy fix, phew

Glad to hear it was something so small.