[Mean E92]

My car recently has developed some sort of knocking sound coming from the engine. Sounds like a bad connecting rod or rod knock. Car is a 2011 BMW 335i with the N55 engine with 85,000 miles. Owned the car since 60k and changed oil every 5k with Castrol Edge 0W-40. At this point, it's financially smarter for me to avoid a used engine if I can. I still owe 10k to the bank. If it was the rod bearings or connecting rods will I be able to just replace those and keep changing the oil for lets say 500 miles for a few months or until there's no more metal? A used engine will go around for 5k. I've been quoted 4k in labor to install it. Then again I have the chance into running into more problems. I'm in a really tough spot and I REALLY need some help. Thanks.

https://www.youtube.com/watch?v=yMeokNp6ppc

[9krpmrx8]

Stop driving it.

Have it checked out by a qualified mechanic or if money is a concern right now, spend $28.00 and send a sample of the oil to Blackstone laboratories.

The Vanos bolts were and issue on some years of the N55 so you might want to see if your VIN is part of that recall (my 2011 335i was not). I'm not sure what it sounds like when that issue shows up.

[Mean E92]

Originally Posted by 9krpmrx8

Stop driving it.

Have it checked out by a qualified mechanic or if money is a concern right now, spend $28.00 and send a sample of the oil to Blackstone laboratories.

The Vanos bolts were and issue on some years of the N55 so you might want to see if your VIN is part of that recall (my 2011 335i was not). I'm not sure what it sounds like when that issue shows up.

I recorded that video when the sound just started. It's been parked for days now. I'm sending it to my indy this week. I called BMW a few months ago and they told me the Vanos bolt recall was already done to the car.

[9krpmrx8]

Ah okay, and you said you changed your oil every 5k, have you noticed any consumption between those oil change intervals? Any chance you ran it low on oil? I do 5000 mile oil change intervals and I always have to add at least a quart, even more if I go on a few hard drives thru the hill country.

[Mean E92]

Originally Posted by 9krpmrx8

Ah okay, and you said you changed your oil every 5k, have you noticed any consumption between those oil change intervals? Any chance you ran it low on oil? I do 5000 mile oil change intervals and I always have to add at least a quart, even more if I go on a few hard drives thru the hill country.

Yes, before the engine made this sound, it consumed oil more then before. I did drive the car harder. I had to add 1 quart at 4300 miles.

[9krpmrx8]

I think that is pretty normal, mine has always required oil to be added. I'm at 80k now. Sounds to me like it could be a fluke. Is your car tuned?

[robthewrench]

Take it for diagnostic or scan for codes. Codes will tell you a lot.

A true engine failure is nearly immediate loss of oil pressure and a seized engine. This is not your problem.

I'll give you a ray of hope here, hopefully you have some sort of fuel / ignition issue and the sound you hear is one or more cylinders not combusting. Typically a rod knock will not give you any codes related to combustion, and the video clearly shows the half engine warning light and codes.

To answer your other question, no on this engine it is typically not worth trying to replace just the crank bearings, or connecting rods. You are usually better off with a used engine.

[Mean E92]

Originally Posted by robthewrench

Take it for diagnostic or scan for codes. Codes will tell you a lot.

A true engine failure is nearly immediate loss of oil pressure and a seized engine. This is not your problem.

I'll give you a ray of hope here, hopefully you have some sort of fuel / ignition issue and the sound you hear is one or more cylinders not combusting. Typically a rod knock will not give you any codes related to combustion, and the video clearly shows the half engine warning light and codes.

To answer your other question, no on this engine it is typically not worth trying to replace just the crank bearings, or connecting rods. You are usually better off with a used engine.

I just dropped the car off to the shop. Codes only show misfires and normal tuner codes. The car sounds bad. So bad. It didn't start the first time or second time. I had to give it a tiny bit of gas. Then it stalled out on me. Not sure if this is because the car hasn't started for a week or if there's another problem. Car is tuned with JB4 but currently not on at this time.

[Joebie]

Have you investigated at all where the noise is coming from in the engine bay?

I'm listening on cheap laptop speakers but to me it almost sounds like you have a horrible exhaust or intake leak. Or like maybe one of your injector hold down clamps came loose and two of your injectors popped out. I'm not exactly sure how the injectors are held in so this is just a hypothetical. Could also maybe be a fluke fuel pump, low or high pressure.

When the noise started, was it sudden? What were you doing when the noise started? Did any other noises happen?

[Mean E92]

Originally Posted by Joester

Have you investigated at all where the noise is coming from in the engine bay?

I'm listening on cheap laptop speakers but to me it almost sounds like you have a horrible exhaust or intake leak. Or like maybe one of your injector hold down clamps came loose and two of your injectors popped out. I'm not exactly sure how the injectors are held in so this is just a hypothetical. Could also maybe be a fluke fuel pump, low or high pressure.

When the noise started, was it sudden? What were you doing when the noise started? Did any other noises happen?

Have not investigated. I was driving when it started. Car then stalled out on me. I kind of have a feeling that something is disconnected too. Got in a minor accident when the car caught air days before the noise happened. Maybe the force of the car being pushed down loosened something?

[Joebie]

Originally Posted by Mad E92

Have not investigated. I was driving when it started. Car then stalled out on me. I kind of have a feeling that something is disconnected too. Got in a minor accident when the car caught air days before the noise happened. Maybe the force of the car being pushed down loosened something?

I'd have to agree with a previous poster that the engine is probably fine. I suspect the problem will be quite apparent once the shop actually starts looking into it.

Best of luck!

[juld0zer]

Love the 2 stroke Vespa

Id have to agree, sounds like you've got a leaky cylinder. Loose spark plug?

[Mean E92]

Originally Posted by juld0zer

Love the 2 stroke Vespa

Id have to agree, sounds like you've got a leaky cylinder. Loose spark plug?

Would it be because the spark plug is rattling?

[Mean E92]

Also would like to note that my JB4 Steering controls stopped working :\

[Twisted Tuning]

Originally Posted by Mad E92

Also would like to note that my JB4 Steering controls stopped working :\

JB4 may have lost connection or something. It doesnt sound like rod knock and etc. At least not from the video. sound more like bad misfiring and etc. But im just going off the video sound.

[Mean E92]

Originally Posted by Twisted Tuning

JB4 may have lost connection or something. It doesnt sound like rod knock and etc. At least not from the video. sound more like bad misfiring and etc. But im just going off the video sound.

In what way could of made it disconnect? The CAN wires?

[Twisted Tuning]

Originally Posted by Mad E92

In what way could of made it disconnect? The CAN wires?

still have no clue. once there was a loose wire. a couple other times, nothing was found wrong with the wiring.

[Mean E92]

Shops still diagnosing. They want to make sure it's not mechanical.

[Bamaben]

Exhaust leak

[Mean E92]

Originally Posted by Bamaben

Exhaust leak

Can an exhaust leak really sound that bad?

[Mean E92]

Shop got back to me and told me it's mechanical. They said it's a spun rod bearing. They didn't drop the pan. Still don't know how this is possible. They then told me they removed JB4 because it was making the car have starting problems. They also compression tested the engine. Apparently 2 of the 6 cylinders aren't balanced. I asked why they couldn't just change the rod bearings and they said that the clearance would be too much. I'm sending it to a well known highly respected BMW only shop next week to see what they say. All of this still dosent add up to me.

[Mean E92]

Anyone else have any other ideas or speculations?