Howling Noise from Engine when Pressing Brakes - 2008 550i
 

Hey guys, I'm working on a buddy's 545i and have a weird problem. After it's warmed up (been driven around), presing the brakes makes it sound like there's a wolf under the hood.

Any suggestions? Everything I see about a howling noise points to the PCV system, but I would like some confirmation.

Thanks!

The Brake Booster runs on the vacuum pump thats on the left side of the engine on the head. I'd check vacuum on it and make sure its in tight and then check the connection on the brake booster under the driver's side front windscreen (under the filter)

Sorry about the late reply; thanks. I checked it, and everything is good there. Here's a video of the noise.

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From the video, it looks like a 545 instead of a 550i. That difference could possibly change what could be the source of the noise.

that is a 545i engine. They are pretty similar though. The only real difference is in the cylinders. Anyway i dont think i've ever heard an engine make a sound like that. If its coming from under the AC filter there (next to the positive battery terminal) then thats where the brake booster is. I'd take off the filters and surrounding plastic underneath and see if something is loose.

Is it because of the engine cover? It's a 2008 550i and is badged as such...thought the engine change in 2005 changed the 545 to 550.

It does sound like it's coming from near the back of the engine, maybe a bit close to the brake booster...I took apart everything save for removing the brake booster and checked it all - no leaks, lines hold vacuum.

Could it be the PCV? Thought I read something about a malfunctioning PCV system making howling noises (will try to find a link). I watched several videos of oil separator malfunctions and they make a completely different, continuous noise.

This starts up when the car is warmed up and comes and goes every several seconds.

CCV system in the N62TU. Yes thats not its engine cover. I'm surprised it even fits on the newer engine. They have a different intake manifold. Anyway, you could do the good old smoke test. That should reveal some vacuum leaks. Did you try and remove the oil dipstick while its running and howling?

Hah, it actually doesn't fit that well...Makes it difficult to put the coil covers on.

I'll try removing the dipstick and get back, tomorrow I'm scheduled to work on it.

First of all, sorry about not getting back sooner...we got hit with a rainstorm. Got good updates!

I replaced the CCV caps, diaphragms, and springs. The old ones were OK, not fouled at all Now the howling noise is constant when the engine is warmed up and idling. Pressing on the gas makes the howling go away.

I stopped it (warm and idling) to open the oil filler cap; the howling reduced, and when the oil filler cap was off the engine stalled immediately.

I was reading this: Timm's BMW M60, M62, M62TUB and N62TUB V8 Engines - PCV, PRV and OSV

Given that I have new CCV cap hardware, where should I look next?

HAH, you guys were right! The owner changed the trunklid to a 550i trunklid, but it's a 2005 545i!

Can a mod please change the thread title to reflect that?