[shiftdnb]

After a 3 hour trip back home I was putting my car in the garage after unloading luggage and I could here a consistent click coming from under the car about midway near the catalytic converter that came every 5 seconds or so. I turned the car off and came back with my phone to record it. It wouldn't give me the consistent click as I was hearing before but it was giving me a weird series of the same sounding clicks after startup (starts at 1:34) and when I shut it down a much more rapid and louder clicking (starts at :07). It sounds almost like relays triggering. I let the car cool down and just went out to see if it was still doing it and it's not so seems to be an issue after warming up. All the clicking videos I've tried to see match are in the engine or the external fuel pump in the previous generations.

[shiftdnb]

Was able to replicate the issue, seems to do it when it's warmed up fully here is the consistent clicking I was hearing. Service scheduled tomorrow.

[shiftdnb]

Dealer is claiming this is heat shield expansion and contraction. To me this does not sound anything like the metallic pinging that usually is associated with that.

[eugene89us]

I hope I am understanding the clicking sound in question correctly. The first video, I have the same clicking noise when the car is shut down - immediately after. We have 2 diesel BWMs, 2017 and 2018, and both make the exact same clicking noise when the car is just shut down for a few seconds before stopping. One is a 6-cyl and the other is a 4-cyl, so it has to be something diesel component related but not engine itself (since we have 2 different engines in the household). I am not sure about consistent clicking when car runs in your second video, I would have to check.

[shiftdnb]

I've heard the first set of clicks in the first few seconds of the video before. The clicks that I am posting about are from 7 seconds to 28 seconds and again at 1:36 in the first video. I took it to an independent mechanic that I know and he said the sound was mechanical and not heat expansion. He thinks it's the SCR metering module. He's going to take a closer look on Thursday for me when he puts on some new tires for me and can put it on a lift.

[tomfromON]

Originally Posted by shiftdnb

I've heard the first set of clicks in the first few seconds of the video before. The clicks that I am posting about are from 7 seconds to 28 seconds and again at 1:36 in the first video. I took it to an independent mechanic that I know and he said the sound was mechanical and not heat expansion. He thinks it's the SCR metering module. He's going to take a closer look on Thursday for me when he puts on some new tires for me and can put it on a lift.

The SCR delivery module typically initiates a reverse operation after the car is shut off to draw left over UREA fluid back to the pump which is most likely what you're hearing.

[shiftdnb]

Originally Posted by tomfromON

The SCR delivery module typically initiates a reverse operation after the car is shut off to draw left over UREA fluid back to the pump which is most likely what you're hearing.

Do you know why it would give a consistent click when running or click twice consistently on start up? The thing for me is this is the first time in 11000 miles I've ever heard that click coming from that area. To be told it's heat shield expansion really just tells me they either didn't understand my complaint or they didn't read my write up or watch the videos at all.

[tomfromON]

Originally Posted by shiftdnb

Do you know why it would give a consistent click when running or click twice consistently on start up? The thing for me is this is the first time in 11000 miles I've ever heard that click coming from that area. To be told it's heat shield expansion really just tells me they either didn't understand my complaint or they didn't read my write up or watch the videos at all.

The SCR system - if related to your complaint consists of 2 pumps and a mixing module that both sound like fuel injectors clicking when working; we're not talking HPFP pressures here however same principle applies. The injection portion(s) are integrated directly into the exhaust pipe which will amplify that sound. It sounds like a normal condition to me but having said that I can only hear it working on mine if I'm outside of the car and near the r/r wheel area.
You may want to escalate that one with your dealer if you're getting the run around from the service advisor.