WTF is this noise

[E92 420]

Ok so had my engine built last year I have only covered around 3500 miles since it’s been done. Everything has been fine. Car runs well, feels well and pulls strong.

Tuned by v8bait, logs look really good

This noise Has developed. It doesn’t get seem to get louder with Rpm in fact I cannot actually hear it when I rev the car engine/ exhaust noise seem to drown it out.

Really doesn’t sound like rod knock to me but I’m scratching my head as to what it could be.

Anyone have any ideas?

Engine and gearbox Mod list below

Forged JE 9.5-1 compression pistons
Carrillo rods
Fully refreshed head (stock)
VTT GC lites v2.0
VTT outlets
VTT inlets
RB high flow oil drains
PSP 750 fmic
Forge CP &BOV
Mosselman oil cooler
CSF rad
Custom twin Mishimoto CC set up
Stock airbox with Z4 lid and mr5 mod
Presion raceworks coils
Ngk 1 step colder plugs
Aquamist hfs4 v3.1 meth kit, 2 1mm nozzles on fmic outlet
Vrsf DP and 3.5” system
RB external PCV system with plugged head ports

Fully rebuilt zf6hp21 with Sonnax zip kit and XHP stage 3

 

[Blaster3500]

If I am hearing the same noise you are describing it sounds like gearbox rattle to me.

 

[E92 420]

If I am hearing the same noise you are describing it sounds like gearbox rattle to me.

Hmm

I’m an auto so no single mass flywheel.

The second video is much clearer. Could you hear it on that video ok?

 

[Blaster3500]

Hmm

I’m an auto so no single mass flywheel.

The second video is much clearer. Could you hear it on that video ok?

Hmm... Is it the it low rumbling noise?

 

[E92 420]

Hmm... Is it the it low rumbling noise?

Yes the low rumbling like noise!

the ticking noise is just the injectors not worried about that.

 

[E92 420]

Added mod list to first post. More info the better right.

 

[Rob09msport]

Pcv vent

 

[DaeDoe]

Kinda sounds like an exhaust leak, my gasket blew out at my downpipe once and it sounded like a helicopter putting. Kinda like the video by the wall, hard to tell by video.

 

[Rcboosted2007]

Did you check the mounts around the radiator and fan. I had a similar vibration. It ended up being a broken AC line clip. It eventually rubber a hole in the line

 

[E92 420]

Pcv vent

Rob,

Could you elaborate a little more on why you think this is what is causing the noise?

I have the RB external pcv set up with plugged head ports

 

[E92 420]

Kinda sounds like an exhaust leak, my gasket blew out at my downpipe once and it sounded like a helicopter putting. Kinda like the video by the wall, hard to tell by video.

Ok well this sounds feasible. I only just installed these turbos very recently and the only gaskets I did not replace were the DP to the Vrsf 2-1 merge gaskets as they were pretty new but I possibly damaged one putting it back in and also the noise is even more pronounced from under the car in the DP area!!!!

The noise sounds the same as the bongo drum noise when you remove the oil filler cap with car running!

 

[E92 420]

Did you check the mounts around the radiator and fan. I had a similar vibration. It ended up being a broken AC line clip. It eventually rubber a hole in the line

Most certainly something I have not checked but I have had my car in bits so much over the last year that it wouldnt surprise me if I have over looked something. Car has done such limited miles over last 2 years now some real heat is getting into it things are settling in and touching etc...

 

[fmorelli]

Don't be surprised. We recently discovered the cooling fan shroud in my car shattered on the bottom. Barry and I work like surgeons, so hard to imagine how we would have caused such a problem. The bottom of the fan shroud is completely enclosed given the undertray. There was absolutely no signs of contact anywhere on this shroud. Bizarre. Stuff just happens sometimes that we can't explain.

That said, the sound you point out in the video is fairly deep. He reminds me more of an exhaust leak. I would think it would be reasonably easy to track down if it wasn't for the fact that the motor is tilted sideways hiding the exhaust. Good luck!

Filippo

 

[E92 420]

Hmmm

Took Under tray off and look what fell out!!!

Vividly remember torquing these to spec and double/triple checking all of them before being happy.

Apologies for upside down pic. iPhone for ya.

 

[E92 420]

Ok so in Total 4 nuts missing!!! And rest are pretty loose!!

Iv done 4 turbo swaps in the 8 years I’ve owned this car stock turbo swap, classic RB’s, turbo dynamic stage 2’s and most recent these VTT GC lites v2’s. Always used OEM copper manifold nuts and never ever had any issues like this. Now the only difference here is VTT supply some really soft non OEM copper mani nuts with these turbos.

so Iv just swapped all the mani nuts back to the hard annealed copper OEM nuts. Torqued back to spec and hopefully no issues like this ever again

 

[Rcboosted2007]

Did you torque them after a heat cycle ?

 

[E92 420]

Did you torque them after a heat cycle ?

I went round and checked/nipped up all the copper nuts after 50 miles yes. Being RHD it’s a major pain to get to some of the rear turbo nuts. Obviously never put enough on em!

 

[Rob09msport]

Rob,

Could you elaborate a little more on why you think this is what is causing the noise?

I have the RB external pcv set up with plugged head ports

Theirs videos floating around but if you have a pcv hose not connected or broken fitting it sounds just like that
Obviously I was wrong though