HELP!!! E90 N52 Engine Rattle

[sygex]

Hello,
I will start by saying that I have read a lot of information and threads before posting and I still cannot seem to figure out my issue.
There are no error codes stored in the computer, the car seems to be driving just fine, no loss of power of fuel efficiency.
The car has been at the dealer as well as Valley Motorwerks - neither of them could diagnose the problem.
I thought the chain guards might be broken, so I took the valve cover off and check everything. Also, checked the VANOS unit, and everything seems to be just fine.
At this point I am concerned that the issue might be a spun rod bearing :(

Please, any help is appreciated.

Here are some videos of the rattle as well as pics with the valve cover off.

https://youtu.be/HC9GJSJ88xw

https://youtu.be/AIBwlL35DFU

594152594153594154594155594156


Thank you guys!


EDIT: The knock is not there when the car is cold. It shows up only after it has been running for around 5 minutes.

[cochise325]

It does sound like a rod knocking. Have you checked motor mounts to be sure the engine is secure?

[sygex]

It does sound like a rod knocking. Have you checked motor mounts to be sure the engine is secure?

Yes, mounts were checked and they were fine. Is there a way to make sure it is a rod knocking?

[floydr]

To help diagnose an internal engine problem (and if it's a rod knocking it's very serious and shouldn't be driven), draw some oil and have an oil analysis done (Blackstone.)

Another thing to check out is the air conditioning compressor - might be that.

Stethoscope to locate the source of the noise more closely.

[sygex]

I will definitely have the oil inspected, thank you for the advice!

I checked the ac compressor by turning it off and on, no change in the sound.

Tried the stethoscope yesterday and the sound seems to be coming from the passenger side, near the exhaust pipes.

I just edit the post above to add that the knock is not there when the car is cold. Is this typical for a bad bearing?

Thank you!

[floydr]

...

I just edit the post above to add that the knock is not there when the car is cold. Is this typical for a bad bearing?



Yes. Cold oil is more viscous and fills the space/cushion in the rod bearing better.

Have some check the actual oil pressure, both cold and hot, to ensure that the oil pump is good.

[mandd]

Hello,
I will start by saying that I have read a lot of information and threads before posting and I still cannot seem to figure out my issue.
There are no error codes stored in the computer, the car seems to be driving just fine, no loss of power of fuel efficiency.
The car has been at the dealer as well as Valley Motorwerks - neither of them could diagnose the problem.
I thought the chain guards might be broken, so I took the valve cover off and check everything. Also, checked the VANOS unit, and everything seems to be just fine.
At this point I am concerned that the issue might be a spun rod bearing :(

Please, any help is appreciated.


Thank you guys!


EDIT: The knock is not there when the car is cold. It shows up only after it has been running for around 5 minutes.


A/C Compressor. Remove the drive belt and see if it goes away.

Mark.

[sleeper bird]

To help diagnose an internal engine problem (and if it's a rod knocking it's very serious and shouldn't be driven), draw some oil and have an oil analysis done (Blackstone.)

Another thing to check out is the air conditioning compressor - might be that.

Stethoscope to locate the source of the noise more closely.
black stone is great advice the can tell quite a lot from the oil sample,I've used them several times

[sygex]

A/C Compressor. Remove the drive belt and see if it goes away.

Mark.

I tried turning the AC on and off and there is no change in the sound.
Can I remove the serpentine belt and still start the car, since the water pump is also driven by it?



black stone is great advice the can tell quite a lot from the oil sample,I've used them several times

Already ordered the test kit, I hope it comes soon.

[mandd]

I tried turning the AC on and off and there is no change in the sound.
Can I remove the serpentine belt and still start the car, since the water pump is also driven by it?


Turning the A/C on and off will have no effect on the mechanical function of the A/C compressor, it just controls a duty cycle solenoid that directs liquid Freon within the case (similar to the VANOS solenoid).
The water pump is not driven by the belt has it is electric, remove the belt and listen for the noise or have your mechanic do it for you.

You will have the alternator and ABS light on when running, but they will go out after refitting the belt and running the car.

There are some issues with the variable displacement compressor fitted in the E90/60/65, the swash plate or lug plate can fail on the shaft and hammer the crank chamber causing a sound similar
to and failed connecting rod or main bearing..

Mark.

[sygex]

Turning the A/C on and off will have no effect on the mechanical function of the A/C compressor, it just controls a duty cycle solenoid that directs liquid Freon within the case (similar to the VANOS solenoid).
The water pump is not driven by the belt has it is electric, remove the belt and listen for the noise or have your mechanic do it for you.

You will have the alternator and ABS light on when running, but they will go out after refitting the belt and running the car.

There are some issues with the variable displacement compressor fitted in the E90/60/65, the swash plate or lug plate can fail on the shaft and hammer the crank chamber causing a sound similar
to and failed connecting rod or main bearing..

Mark.

Thank you Mark, this was very informative. I will give it a try after work today and will post the result. I appreciate all of your help!

[chris33]

The water pump is electric, so removing the belt will have no affect on the cooling. Remove the belt and see if there is a change.

[sygex]

Well, I took the belt off and the sound was still there and exactly the same. At this point I am almost sure it is a rod bearing, but to be completely sure, I will wait for the oil results. I will either be replacing the bearings or the whole engine. Too bad I don't have a lift at home.

If anyone has any other ideas, please share.

Thanks everyone!

[Wormy]

I have seen a few posts with the same/similar problem, there would be slight rattling noise seemingly coming from engine bay, heard most at idle and/or low rpm in the car when driving or stopped at light. Was also heard when starting the car. Well, I was changing the air filter, and as I was moving the air box around to get it out, it seemed to hit or touch metal under the box. When I had it removed, I realized that there USED to be a rubber cone, onto which air box will position itself, and float when fastened with two grommets on the driver side of fender. Rubber cone was missing, probably got stuck to air box and fell out at previous filter change. So I taped some high density foam at contact points where air box housing touched the frame, and VOILA no more rattling noise! Simple as that! :Dhttps://www.bimmerforums.com/forum/showthread.php?2337076-HELP!!!-E90-N52-Engine-Rattle

[Wormy]

OOPS... try this one instead... sorry, new to posting links... I am having a rattle myself in my E90 and have been looking this morning at some earlier posts by others... found a few interesting posts from earlier 3 series owners as well I will try to post in second link... https://www.bimmerforums.com/forum/showthread.php?2097754-SOLVED-idle-and-low-rpm-rattle-from-engine-bay-E90, http://www.bimmerfest.com/forums/showthread.php?t=228249, http://www.e90post.com/forums/showthread.php?t=920797 There are Many posts on here so happy surfing, I too am searching for the elusive answer... as time permits... I also have an incredible technician that works on my ride. Call him at (828) 324-6016 and ask for Curt as he may have an idea. I haven't had time to ride by and see him but will do so asap and repost.

[TSK02]

Dealing with the exact same issue, 2007 328i coupe, (133K) changed the drive belt and tensioner pulley, and idler , thinking one of the bearings was bad.
Vibration at low idle but the car runs great. I am betting its the Vanos, and the head has some damage common to the 2007 models. I don't think 2007 and later can be repaired like the earlier models .Super not looking forward to the estimate to replace head
to remedy the problem. I hope I am wrong.