[aceinspace]

Okay, so here’s my story (apologies in advance for the essay – grab a coffee, we’re going on a ride!).

I bought my 2007 335i (auto) seven months ago, with the dealer selling the dream: Fully inspected, A1 mechanically, one owner, full logbook history (which all seemed to check out). It had mid-range klms (115,000), no obvious oil leaks or smell, no sounds, no error codes, DME saying all levels and brakes were sweet. Short of getting it up on the hoist myself, it checked out.

Within a week, I realised the brakes were shot via an incessant chirp at low speeds, which I was told was just "wear and tear" and had to fork out $650 for, even though I'd only put about 350km on it. Since then, it's had the DME fail (replaced - turns out all the perfect levels when I bought it were just default/dummy readings), the alternator fry (replaced), both turbos fail (replaced), coil packs replaced, radiator leak, O2 sensor faults, oil sensor fault... the list goes on. Over $12K worth of work done on top of the $25K I paid in the first place! Luckily, the aftermarket warranty has covered the majority of the work.

However, upon picking it up from the latest repair (turbos replaced) last week, two new things were instantly noticeable: a burning oil/rubbery smell, and a loud rotational squeal/chirp ONLY when turning left, and ONLY noticeable with the vents open (AC on). The sound itself doesn’t appear to be distinctly aligned to either side, but I guess it's probably more noticeable centre/left.

I was originally told the smell would likely just be residual oil on the exhaust from the repair, however it has not gone away. Also gave it a good, hard drive over the weekend and noticed smoke coming from the engine bay/right wheel arch, so I stopped immediately and took it back in. Had it looked at again, and there appears to be oil weeping out of the sump gasket – which they now say they noticed when replacing the turbos – so it’s now booked in to have that replaced. Why they didn’t do they for significantly cheaper when the turbos were out/engine was apart is beyond me, but I digress…

While that’s out, I’m getting the oil sensor and engine mounts replaced as well (also shot).

The sound, on the other hand, is yet to be diagnosed. They said they couldn’t hear it at first, and when I showed them this recording, they just shrugged and said they had no idea. Which brings me here.

Has anyone experienced this sound before?

https://streamable.com/1226i

Again, it’s ONLY when turning left, and ONLY noticeable with the vents open.

I’ve seen some people suggest it could be the AC condensate drain pipe being clogged (however there’s no leak or water sound), others say belts or bearings, some say brakes, and I’ve looked up a few videos but most are different sounds to what I’m experiencing.

My other question is, could the two be linked? Given they started at the same time, and the burning smell is rather rubbery/synthetic, is there a chance the smell could, in fact, be rubber burning somewhere and not the oil leak? Perhaps something wasn't fastened correctly and is rubbing on left-hand turns? The smell is similar to when the alternator fried, but the sound is different.

It's booked to get the sump gasket replaced next week (with a different workshop), but I'd like to have more of an idea before that.

Thanks in advance for any and all suggestions!

[axe127]

I had a pretty similar issue recently. I had a squeal coming from the AC fan when I was turning left or decelerating. It was worse on low fan speeds.

I sprayed some lubricant on the fan bearing and it's been fine now for over a month. I'm sure it's better to actually disassemble the fan to do it, but I figured I'd try this lazy method first.

With the cabin air filter removed, you can see the fan through the hole in the left circle below. You can then spray it pretty easily if your lube-o-choice has a straw attachment.

[tlow98]

Yeah, squirrel cage fan that’s above the passenger foot well. Costs about $100 and takes 30 minutes to replace. A dealer will want $3-400 I’d guess.

Common issue with these cars - right down to the left hand turn Symptoms.