135i siren / oil

[135iNathan]

Hey all this is my first post and looking for some insight- from the 1500-2500 rpm range I get a siren/whistle noise, it's only present while boost is building and when the car is under load, it does not make any noise when the car is in park. I just had new turbos installed with upgraded waste gates to prevent rattle in the future. The car pulls strong and doesn't hesitate in the slightest, I checked all the connections in the engine bay and they are secured.

Another thing is the car has been maybe driven 1000km and the oil level has also gone down but there's no visual leaks and there's no smoke coming from the exhaust, no build up in the usual places like the oil cooler or around the filter can't figure out where it's going.

I'm praying that it's a vacuum leak somewhere that I've overlooked and not shaft play causing the noise

Any previous experience reflecting to a similar situation would be appreciated

Within the last 3000km I've done
-Turbos
-Waterpump
-timing
-every engine gasket
-vanos solenoids
-all pulleys and belts
-coolant lines
-oil cooler
-power steering lines
-coils and plugs



Car is a DCT 2008 135i with 201,000 km

I've linked a YouTube video with an identical sound as it won't let me upload the clip I recorded

[dtla1]

Unless you have a one off concept, or unless there's something weird going on (transmission swap?) I don't think you have a DCT 2008 135i. It's probably the SMG trans with the paddle shifters, but not a DCT. I don't think that really matters here since it's most likely the engine making that noise and not the transmission.

Anyways, it kinda sounds like a small air leak somewhere. Check your inlet to turbo connections. If it does it while in neutral, have someone accelerate and search around with your ears to see if you can pinpoint.

My first thought was rear main or the front crank seal, but I'm not too sure.

[135iNathan]

Originally Posted by dtla1

Unless you have a one off concept, or unless there's something weird going on (transmission swap?) I don't think you have a DCT 2008 135i. It's probably the SMG trans with the paddle shifters, but not a DCT. I don't think that really matters here since it's most likely the engine making that noise and not the transmission.

Anyways, it kinda sounds like a small air leak somewhere. Check your inlet to turbo connections. If it does it while in neutral, have someone accelerate and search around with your ears to see if you can pinpoint.

My first thought was rear main or the front crank seal, but I'm not too sure.

Originally Posted by dtla1

Unless you have a one off concept, or unless there's something weird going on (transmission swap?) I don't think you have a DCT 2008 135i. It's probably the SMG trans with the paddle shifters, but not a DCT. I don't think that really matters here since it's most likely the engine making that noise and not the transmission.

Anyways, it kinda sounds like a small air leak somewhere. Check your inlet to turbo connections. If it does it while in neutral, have someone accelerate and search around with your ears to see if you can pinpoint.

My first thought was rear main or the front crank seal, but I'm not too sure.

Yeah my bad it's a smg, and it doesn't do it in neutral only in drive, going to try to see if the rear inlets disconnected today

[zx10guy]

I don't even think it's an SMG. I'm pretty sure it's a 6 speed ZF auto. I only know of 3 transmission options for our cars: 6 speed manual, 6 speed ZF auto, and 7 speed DCT. The DCTs only became an option when the N55 motor appeared.

[Captain Blood]

I'm putting in a quart every 5000 miles or so. No apparent leaks. Seems normal for these cars.

[elitesales305]

didn't mention cp upgrade on your recent things done..
when I was in low rpm range, I was getting a "fat in a tunnel" sound..
don't wanna downplay your knowledge or expertise xspecially on ur own vehicle..but if u did change the cp while also doing all these others mods,maybe the fart in tunnel noise ur getting is it. if not …. sorry hahaha