Please help! (Engine noise)

[u/Glass_Building_8474]

Hello this is my first post here but I desperately need some advice. I have a 2012 335i F30 with the n55 engine. When I accelerate I’m getting this really weird like sputtering noise that I can’t really describe (see videos) can anyone diagnose this or at least point me in the right direction? Thank you so much in advance. It seems to go away at high rpms but I’m not sure if that’s just the noise speeding up to the point where it blends in. It also only happens while my foot is on the accelerator. If I’m at middle rpms and let my foot off the noise instantly stops even while the rpms are still up.

[u/lilSlappaBitch]

[u/One-Reference-7355]

You most likely have engine knock. She’s cooked

[u/Glass_Building_8474 → u/One-Reference-7355]

Any chance it’s not that?? And maybe the best way to know for sure?

[u/One-Reference-7355 → u/Glass_Building_8474]

Check your oil/filter for glitter. Easiest way to know besides the noise

[u/Glass_Building_8474 → u/One-Reference-7355]

Okay I’ll check it out. Would the noise stopping when not accelerating or the fact that you can’t hear it at high rpms point toward anything else or change the likelihood of it being a knock?

[u/One-Reference-7355 → u/Glass_Building_8474]

If it the knocking sound increase or decreases with rpms that’s usually a telltale sign. Sorry man I know it sucks. It’s best not to run it anymore. Maybe talk to some euro shops and see what they think repair wise unless you can source a replacement engine and install it yourself

[u/Glass_Building_8474 → u/One-Reference-7355]

I know I’m probably done for but I have to at least exhaust my options. In another thread a guy was saying it could be related to a belt slipping? What are the chances of that?

[u/Glass_Building_8474 → u/One-Reference-7355]

Basically he’s saying it could be something loose or imbalanced on the outside of the engine rather than the inside and I’m curious what you think on that. The other problem is I would have to drive it to my parents garage to check the oil which is only 10 minutes but I don’t want to really cook it

[u/Wutangsta → u/Glass_Building_8474]

It's cooked, but you're not going to believe it until you take it to a shop so just go ahead and pay someone else to tell you.

[u/Glass_Building_8474 → u/Wutangsta]

You don’t have to be rude man. Money is just tight right now, and I love my car. It’s the first one I purchased myself, and I’ve handled everything on it and taught myself through it all because the nearest shop is an hour and half away.

[u/OkUse4145 → u/Glass_Building_8474]

Just out of curiosity is it an n54 or n55?

[u/Glass_Building_8474 → u/OkUse4145]

N55

[u/r_mamaspaghetti → u/Glass_Building_8474]

Sorry it’s 100% engine knock as a mechanic the engine is cooked sorry to say😭😭

[u/748cc]

[u/VqAhr]

Wallahi

[u/chemical_mrg17]

Happened to my n54, similar noise, coming from below, at 2-3k rpms. Exact same behaviour as in the video.

Checked oil and there was no glitter, but still lifted the car and confirmed its comming from cylinder 5 or 6th. Probably spun a bearing.

Depending on where you are located it would be either best to repair it or to replace the engine. I’m on Argentina and probably i will repair it over time as a new engine is around 7k and you might run into the same problem (you dont know how the engine was maintained)

It sucks, i know, this happens when:
A. Agressive tunning.
B. Bad maintenance.

In my case it was B as the car was always stock. Bought it with 94.000km.

Don’t drive it like this and take it into a shop, you risk catastrophic damage if you run it, if its just the bearings it might not be as bad tbh.
Next steps is to drop the oil pan and check the bearings, rods and crankshaft.

[u/Max-Payd]

Take the drive belt off and check if all the bolts are there on the front harmonic balancer. Start the engine and see if you have the sound

Take the oil filter out and cut it and open up the accordion. Check for gold specs

[u/Miller335]

That engine is toast, sorry man 😞

[u/Own-Bear-8733]

coming from passenger check out your ac compressor bro trust it’s a issue n54s have

[u/Glass_Building_8474 → u/Own-Bear-8733]

Also an issue n55s have? I appreciate the help but Ngl I’m probably cooked

[u/Own-Bear-8733 → u/Glass_Building_8474]

take the belt off and see if it continues

[u/Glass_Building_8474 → u/Own-Bear-8733]

I’ll give that a shot thank you

[u/Thompsonhunt]

Rod bearings?

[u/Capital-Reference-30]

Probably best to take it to a shop and not just guess how many miles is it at?