[sleepysnake]

Gents, and Ladies,

I have an issue with my 129k mile 05 330i. It has been going on for at least the last 6 months, but may have got slightly worse recently with a clearly audible (with the windows open) slow knocking noise when stopped after driving for a few minutes from a cold start.

Please turn your audio up and listen to this:

The symptoms are:

- With a cold engine, you can hear a rattle sound that goes up in frequency with the revs as soon as you start up regardless of clutch in and out and when above 1k rpm. This sound only occurs when the engine is cold.

- Once the engine has finished its cold start up routine, or after a minute of driving, if you stop you can hear this rattle at idle, it is quite slow and in rhythm with the rpm. It sounds like a knock.

- Within 4-5 mins of driving, the sound is gone, the engine is smooth and no rattles are to be heard. The rattle/knock slowly gets quieter.

- The video was taken without a drive belt on the engine. This rules out any pulley or accessory.

- I have not had any issue with driveability, or any codes showing up. The engine delivers strong performance.

- It sounds like the noise is coming from the cylinder head area close to the intake manifold. I don't see how it can be the DISA if the sound disappears once warmed up.

- An oil change to a MANN filter and Mobil 1 ESP 5w30 made no difference.

- Car is always run on 99 octane petrol.

- The car has done 3k more miles since May 18.

I'd be interested to hear any other thoughts on what this is.

[sleepysnake]

EDIT - removed this video which is just DMF rattle. The bad rattle is only heard with a cold engine.

[sleepysnake]

Replaced the chain tensioner with a new OEM unit. The old one looked fine and took the same amount of force to push against the tension as the new one. I will accept it's a noise that the engine makes that hasn't got any worse in 2 years and will try to not let it bother me. Only heard at idle when parked next to a car / wall. The engine is still happy to be run at 4-7k rpm on a windy road for 30 mins.

As this was one of the E90 launch press cars in early 05, perhaps the hard life it most likely had back then was what caused this. Too much aggressive driving with a cold engine?

In other news, discovered during the shakedown run post install, now the idrive keeps rebooting with only the BMW splash screen displaying. That's another few hundred £ to get it sent off for a mainboard repair...

[rothwem]

I've had 3 N52 cars and they've all had the same rattle at idle. I don't know what it is, but like you mentioned, it doesn't seem to hurt the car. I would like to know what causes it, but for now, I've just accepted it as "an N52 thing"

[Joebie]

You mean the clicking "card-in-bicycle-spokes" noise?

Or do you mean the extremely faint less consistent low pitched noise?

The first one is normal, the second one could be the DMF getting old. Try pushing in the clutch and listening for the noise to go away. The best way to describe how the DMF normally sounds like a helicopter very far away at idle.

Maybe I'm just not hearing the noise you're talking about but everything in the videos you posted sounds perfectly normal to me.

[go_threethirty_go]

hard to tell the actual noise but I have found this will help eliminate the lifter tick: https://products.liqui-moly.us/mos2-...treatment.html

You could get a cheap mechanics stethoscope to help isolate the noise.

In addition to the actual engine, I'd check the bolts at the sides of the windshield cowl (I believe they are 10mm)

I would also check the rubber piece below the airbox to make sure that it is still present and in decent condition. (your airbox design is different(better) than n52 sold here but the rubber mount is likely still in use)

[sleepysnake]

I mean the dull rattle you can hear in the first video at 1:15, which isn't the DMF - no difference with clutch in or out.

[Dbissel1]

Hi, sorry to wake up your relatively old post.. But I’m having the exact same issue right now! I’m too scared to even drive it! Did you ever come up with a fix for this? And if not, is the car still behaving for you? I’m 100% sure my noise is exactly the same..

I’m actually from Worcester too! Dont see many of us around here in petrol e90’s!

Thanks, Dale

[Dbissel1]

[longtermproject]

I had a sound similar to this, which eventually led to a low oil light on the dash. For me, it turned out to be the bolt that goes to the timing cover that is commonly broken by the intake manifold. Look between the oil filter housing and the intake manifold for a broken off bolt head; mine was flush with the housing, and the head of the bolt was in the recessed area nearby.

[Needbmwpartzz]

Check engine cover bolts.... N52 has many strange engine noises that pop up over time.

[desertman123]

In the OP's video, about 30 seconds deep thats what I hear in my motor (when the revs drop and you hear a rattle)

No clue what it is but I've heard it for like a year now so I figured if anythings broken it would've shown by now. Maybe just the valvetronic system responding to the drop in RPM?

[Doesha]

I've heard plenty of n52's have this. It isn't the known tick noise from lifters. I just accept it on mine although mine isn't as loud. But at the same time your fuel or petro whatever you call it is different then here in the states. Check the heat shield towards the rear of the firewall on passnelger side. I've seen some people jam washers on it which stopped some rattling noise.

[Dbissel1]

The OP’s original video, at 1:15, their car makes an absolutely identical noise to the video I’ve posted above, so it must be something common.. A good friend of mine has the same car but doesn’t seem to get the same noise (at least not as loud!).. Its so strange, I’d really like to come up with a fix at some point.. Just hope it’s not causing further damage in driving it

[sleepysnake]

Originally Posted by Dbissel1

The OP’s original video, at 1:15, their car makes an absolutely identical noise to the video I’ve posted above, so it must be something common.. A good friend of mine has the same car but doesn’t seem to get the same noise (at least not as loud!).. Its so strange, I’d really like to come up with a fix at some point.. Just hope it’s not causing further damage in driving it

Thanks for the reply. Funny that you live in Worcestershire. I live in Worcester.

I have since narrowed down the noises made in the videos. The first one, clattering rattle at idle still occurs. The other noises (dull knock sound) in the videos were the DMF and go away with the clutch in. The primary issue occurs when:

- With a cold engine, you can hear a rattle sound that goes up in frequency with the revs as soon as you start up regardless of clutch in and out and when above 1k rpm. This sound only occurs when the engine is cold.

- Once the engine has finished its cold start up routine, or after a minute of driving, if you stop you can hear this rattle at idle, it is quite slow and in rhythm with the rpm. It sounds like a knock.

- Within 4-5 mins of driving the sound is gone, the engine is smooth and no rattles are to be heard. The rattle/knock slowly gets quieter.

- I have not had any issue with driveability, or any codes showing up. The engine delivers strong performance.

- It sounds like the noise is coming from the cylinder head area close to the intake manifold. I don't see how it can be the DISA if the sound disappears once warmed up.

- An oil change to a MANN filter and Mobil 1 ESP 5w30 made no difference.

- Car is always run on 99 octane petrol.

- The car has done 3k more miles since the original post.

I'd be interested to hear any other thoughts on what this is.

[sleepysnake]

Just seen the other comments on the thread. I'll be checking for broken bolt heads around the intake manifold area and on the valve cover. Strange that you can't hear it when the engine has warmed up though.

Dbissel - your sound does sound exactly like mine. Is it only with a cold engine?

[Doesha]

All the 2005/6 N52's past 100k I've seen always sound loud when cold started for the first minute. And once fully warmed up they sound 10 times better. Plus at a 100k they are really at half their life. Plenty of people in these forums have gone past 200k doing regular maintenance and replacing normal wear parts. Most of them do complain about cold start sound lifter tick, vcg leak, broken bolt like needbmwpartzz stated, oil filter housing gasket, and the occasional oil pan gasket. Oh can't forget the power steering reservoir that leaks. These engines are solid engines,

Have you done a vacuum leak check? Check to see if the radiator fan isn't rubbing in something. Have you pulled off the belts and looked at the pulleys.

[sleepysnake]

That video was taken without the drive belt on. The radiator fan is fine, in fact I don't think it even runs during warm up.

It sounds very much like something internal. Not much I can do about it. I could take it to a BMW specialist here in the UK, but they mostly only deal with diesels and have likely not often opened up the valve cover to take a look at the valve train in an N52.

I feel guilty now for just installing an M3 steering wheel. Cost me about $190. Neglecting a difficult to solve engine sound only heard when cold and focusing on getting a better feeling in my hands...

[juld0zer]

Vacuum pump?

[tommy-999]

I have the same exact sound, when cold it rattles between 1200 and 1800 rpm and after few minutes of idling it goes away. It looks like it is coming from the vacuum pump area but I am not sure. Can vacuum pump cause this?