vibration at idle

bigxO · 10-31-2024, 11:04 PM

I’ve been noticing a vibration in my 328i E90 (N51 engine) for a while, and it seems to be gradually worsening. The vibration is only present when the car is idling—whether I’m at a stoplight or in park—and it disappears as soon as I start driving or increase the RPMs.

I suspect it might be related to the motor mounts or transmission mount, but I haven’t done any inspections or diagnostics yet. What could be causing this, and what’s the best approach to identify and fix the issue?

Phil325i · 11-01-2024, 04:36 AM

If it's motor mounts, open the hood and watch the behavior of the engine when you blip the throttle. If the mounts are shot, the engine will rock side to side.

bigxO · 11-01-2024, 08:00 PM

I’ll give that a try and see if there’s any movement when I blip the throttle. If the engine does rock side to side, is there a specific way to check which mount (or mounts) might be the culprit? I might just end up replacing all the engine mounts and the transmission mount since I’ll already be in there, if that’s the issue. Also, any recommendations on replacement mounts? I want to make sure I get ones that will last or be better.

Phil325i · 11-02-2024, 05:19 AM

I'd always replace both engine mounts if I were you. I can recommend the transmission mounts from Rogue Engineering (at least for manual).

https://www.rogueengineering.com/Rog...air_p_137.html

bigxO · Yesterday, 08:55 PM

I tried stomping on the gas while holding the brake in D, but I didn’t notice any significant engine movement, so I’m not sure if it’s the motor mounts. The car has almost 140k miles, and I’m not sure if the mounts have ever been replaced since I just bought it recently. Is there anything else I should check to rule them out, or should I just go ahead and replace them given the mileage?

Phil325i · Today, 05:02 AM

I think BMW mounts are pretty solid. I only replaced mine (at similar mileage to yours) as preventive maintenance when the sump gasket was changed.

sabino56 · Today, 10:00 AM

You might check the over running alternator pulley. Mine locked up and it caused a vibration at idle. When it’s idling and vibrating look at the tensioner - if it’s jumping that’s one sign that the OAP could be bad. There is a thread on this somewhere here if interested

10-31-2024, 11:04 PM	#1
bigxO Registered 0 Rep 8 Posts Drives: 2011 BMW 328i Join Date: Aug 2024 Location: memphis, TN iTrader: (0)	vibration at idle I’ve been noticing a vibration in my 328i E90 (N51 engine) for a while, and it seems to be gradually worsening. The vibration is only present when the car is idling—whether I’m at a stoplight or in park—and it disappears as soon as I start driving or increase the RPMs. I suspect it might be related to the motor mounts or transmission mount, but I haven’t done any inspections or diagnostics yet. What could be causing this, and what’s the best approach to identify and fix the issue?
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11-01-2024, 04:36 AM	#2
Phil325i Brigadier General 639 Rep 3,214 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	If it's motor mounts, open the hood and watch the behavior of the engine when you blip the throttle. If the mounts are shot, the engine will rock side to side. __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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11-01-2024, 08:00 PM	#3
bigxO Registered 0 Rep 8 Posts Drives: 2011 BMW 328i Join Date: Aug 2024 Location: memphis, TN iTrader: (0)	I’ll give that a try and see if there’s any movement when I blip the throttle. If the engine does rock side to side, is there a specific way to check which mount (or mounts) might be the culprit? I might just end up replacing all the engine mounts and the transmission mount since I’ll already be in there, if that’s the issue. Also, any recommendations on replacement mounts? I want to make sure I get ones that will last or be better.
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11-02-2024, 05:19 AM	#4
Phil325i Brigadier General 639 Rep 3,214 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	I'd always replace both engine mounts if I were you. I can recommend the transmission mounts from Rogue Engineering (at least for manual). https://www.rogueengineering.com/Rog...air_p_137.html __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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Yesterday, 08:55 PM	#5
bigxO Registered 0 Rep 8 Posts Drives: 2011 BMW 328i Join Date: Aug 2024 Location: memphis, TN iTrader: (0)	I tried stomping on the gas while holding the brake in D, but I didn’t notice any significant engine movement, so I’m not sure if it’s the motor mounts. The car has almost 140k miles, and I’m not sure if the mounts have ever been replaced since I just bought it recently. Is there anything else I should check to rule them out, or should I just go ahead and replace them given the mileage?
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Today, 05:02 AM	#6
Phil325i Brigadier General 639 Rep 3,214 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	I think BMW mounts are pretty solid. I only replaced mine (at similar mileage to yours) as preventive maintenance when the sump gasket was changed. __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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Today, 10:00 AM	#7
sabino56 Private First Class 89 Rep 153 Posts Drives: 2006 E90 330i Join Date: Mar 2018 Location: AZ, Tucson iTrader: (0)	You might check the over running alternator pulley. Mine locked up and it caused a vibration at idle. When it’s idling and vibrating look at the tensioner - if it’s jumping that’s one sign that the OAP could be bad. There is a thread on this somewhere here if interested
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