Metallic rattle under load

Sendmewagons · 09-20-2023, 11:15 AM

I'm struggling to track down a metallic rattle on an E91, RWD, N52, MT. I'm really leaning towards something with the VANOS based on the rev range.

Happens between 2-3k rpm
Seems to be coming from engine/gearbox area
Only when in gear. Reving the engine in neutral sounds totally fine
Especially noticeable in 4th gear uphill, but can hear a bit of it regardless
No odd sounds at idle and idle seems smooth
Sounds fine at WOT, but maybe its just noise taking over.
Difficult to hear it with the windows down. Its pretty noticeable with the windows up though.
New coils and plugs very recently. Also did waterpump, accessory belt/tensioner.
New motor mounts (passenger side was collapsed)
I swapped to MT and that is when I noticed the noise. It may have been present with the auto too, but I cannot recall. The auto might have kept it out of the rev range where it is most noticeable.
I did swap a 3SIM into the car, but the noise was present before and after (so not DISA valve noise).
There are some increased metals in my oil sample I took a while ago (before MT swap and before the noise). (My Oil)/Avg
Aluminum 25/8
Iron 29/13
Lead 10/2

Thoughts based on perusing a lot of threads.....

Exhaust heatshield somewhere: I tightened an exhaust bracket thinking it may have been it, but it wasn't. The heatshield on the passenger side near the transmission seems somewhat unsupported to me like it could rattle... all the fasteners are in though. I found the driveshaft heatshield close to the CSB so I adjusted that. No change.
Pinging/Pinking: Seems unlikely with the knock sensors, but I have seen another thread mention high octane gas making a similar issue go away.... Running gas with techron in it now.
Vanos bolts: My car build is 10/2008 so too early for this issue I think. I looked with a boroscope through the oil cap and the design of the gear seems different that the one with the bolts that back out.
VANOS: Suggested to clean the drainback valves and clean/replace solenoids. My drainback valves were clean. Haven't cleaned or replaced vanos solenoids yet.
DISA valves: I have a 3SIM, but the noise was present before I added it. No change after adding it and I have not installed the tune for it yet.

drawz · 09-21-2023, 08:47 PM

I had a metallic rattle related to a slightly loose oxygen sensor. Impressed that my indy mechanic found that one on the first try. Maybe that means it's somewhat common?

Sendmewagons · 09-24-2023, 09:44 PM

Quote:

Originally Posted by drawz

I had a metallic rattle related to a slightly loose oxygen sensor. Impressed that my indy mechanic found that one on the first try. Maybe that means it's somewhat common?

Hmm. I'll check next time I am under there.

Sendmewagons · 10-12-2023, 09:09 PM

Bump?

I was wondering the other day if maybe I got a bad set of plugs somehow that could be causing this. I don't have my old ones.... I kind of doubt it anyways.

Also revising the range of RPM I hear the noise. It can be heard from 1000 RPM up to cutting out around 2700 RPM.

09-20-2023, 11:15 AM	#1
Sendmewagons Private First Class 106 Rep 187 Posts Drives: BMW E30 Join Date: Jun 2020 Location: Somewhere iTrader: (1)	Metallic rattle under load I'm struggling to track down a metallic rattle on an E91, RWD, N52, MT. I'm really leaning towards something with the VANOS based on the rev range. Happens between 2-3k rpm Seems to be coming from engine/gearbox area Only when in gear. Reving the engine in neutral sounds totally fine Especially noticeable in 4th gear uphill, but can hear a bit of it regardless No odd sounds at idle and idle seems smooth Sounds fine at WOT, but maybe its just noise taking over. Difficult to hear it with the windows down. Its pretty noticeable with the windows up though. New coils and plugs very recently. Also did waterpump, accessory belt/tensioner. New motor mounts (passenger side was collapsed) I swapped to MT and that is when I noticed the noise. It may have been present with the auto too, but I cannot recall. The auto might have kept it out of the rev range where it is most noticeable. I did swap a 3SIM into the car, but the noise was present before and after (so not DISA valve noise). There are some increased metals in my oil sample I took a while ago (before MT swap and before the noise). (My Oil)/Avg Aluminum 25/8 Iron 29/13 Lead 10/2 Thoughts based on perusing a lot of threads..... Exhaust heatshield somewhere: I tightened an exhaust bracket thinking it may have been it, but it wasn't. The heatshield on the passenger side near the transmission seems somewhat unsupported to me like it could rattle... all the fasteners are in though. I found the driveshaft heatshield close to the CSB so I adjusted that. No change. Pinging/Pinking: Seems unlikely with the knock sensors, but I have seen another thread mention high octane gas making a similar issue go away.... Running gas with techron in it now. Vanos bolts: My car build is 10/2008 so too early for this issue I think. I looked with a boroscope through the oil cap and the design of the gear seems different that the one with the bolts that back out. VANOS: Suggested to clean the drainback valves and clean/replace solenoids. My drainback valves were clean. Haven't cleaned or replaced vanos solenoids yet. DISA valves: I have a 3SIM, but the noise was present before I added it. No change after adding it and I have not installed the tune for it yet.
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09-21-2023, 08:47 PM	#2
drawz Second Lieutenant 78 Rep 239 Posts Drives: 06 330xi 6MT, 08 535xiT 6MT Join Date: May 2009 Location: Newton, MA iTrader: (0)	I had a metallic rattle related to a slightly loose oxygen sensor. Impressed that my indy mechanic found that one on the first try. Maybe that means it's somewhat common?
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10-12-2023, 09:09 PM	#4
Sendmewagons Private First Class 106 Rep 187 Posts Drives: BMW E30 Join Date: Jun 2020 Location: Somewhere iTrader: (1)	Bump? I was wondering the other day if maybe I got a bad set of plugs somehow that could be causing this. I don't have my old ones.... I kind of doubt it anyways. Also revising the range of RPM I hear the noise. It can be heard from 1000 RPM up to cutting out around 2700 RPM.
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