2021 530e rough first gearshift and groaning noise in electric mode

d4700 · 10-31-2024, 01:16 AM

2021 530e, 74k miles. Doesn't matter if the fluid is warm or cold, I have a rough first gearshift (is it 1-2? 2-3? who knows, I don't know which gear it sets off in) in electric mode with the engine not running (no problem with engine on). Not a violent jolt, but a noticeable "bump" under light acceleration whereas the other gearshifts are basically imperceptible.

Under heavy acceleration in electric mode, I hear a faint groaning noise (almost like an engine revving at low RPM) before and during the first gear change after setting off. It's very faint, to the point where I imagine someone with slightly older ears than I would not pick up on it.

I attribute some of this to me being overly sensitive - owning hooptie BMWs in the past has given me a keen eye and ear for potential issues - but my hypothesis is that the fill level in the gearbox may be slightly off or the fluid overly degraded, and the noise and inertia of the running engine connected via the separating clutch in sport/hybrid mode masks the issue. I'm hoping this is the issue as I'll be doing a fluid change (with Fuchs 6008 if anyone's curious) shortly, but if anyone else has experienced a similar problem with the PHEV, I'd love to know about it. Thanks!

LogicalApex · 10-31-2024, 10:57 AM

I can't speak to the groaning noise as I haven't heard it. But it is possible I haven't listened for one either...

That said, a jerking on acceleration at low speeds is common. It can happen on EV only mode as well so it isn't related to the engine engagement clutch. When I've asked BMW about this they said it is just a thing the ZF transmission does and isn't a problem. It isn't something I always experience, but I do experience it from time to time. BMW stressed that if there are any problems with the transmission it will throw codes and it hasn't done that yet.

It has been covered on the forums from time to time as well.

So far, my car has been otherwise fine over 50K miles and 5Y. I've owned it since new FWIW.

d4700 · 12-06-2024, 08:32 PM

A quick update - I did a spill and fill with Fuchs 6008 fluid last week. Dropped about 4 liters and put exactly the same amount in, rechecked after a drive to get the fluid above 75C (thermostat opens), and the level was bang on (slow drips at 40C).

Shift quality is marginally improved, but the soft groaning noise from 2-3 persists in EV mode. I may look into changing the filter as well at some point to see if this improves, but the noise hasn't gotten any worse at this point and doesn't impact driveability. I think I'm just overly sensitive!

10-31-2024, 01:16 AM	#1
d4700 Enlisted Member 18 Rep 38 Posts Drives: 2021 530e Join Date: Mar 2023 Location: Phoenix, Arizona iTrader: (0)	2021 530e rough first gearshift and groaning noise in electric mode 2021 530e, 74k miles. Doesn't matter if the fluid is warm or cold, I have a rough first gearshift (is it 1-2? 2-3? who knows, I don't know which gear it sets off in) in electric mode with the engine not running (no problem with engine on). Not a violent jolt, but a noticeable "bump" under light acceleration whereas the other gearshifts are basically imperceptible. Under heavy acceleration in electric mode, I hear a faint groaning noise (almost like an engine revving at low RPM) before and during the first gear change after setting off. It's very faint, to the point where I imagine someone with slightly older ears than I would not pick up on it. I attribute some of this to me being overly sensitive - owning hooptie BMWs in the past has given me a keen eye and ear for potential issues - but my hypothesis is that the fill level in the gearbox may be slightly off or the fluid overly degraded, and the noise and inertia of the running engine connected via the separating clutch in sport/hybrid mode masks the issue. I'm hoping this is the issue as I'll be doing a fluid change (with Fuchs 6008 if anyone's curious) shortly, but if anyone else has experienced a similar problem with the PHEV, I'd love to know about it. Thanks!
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10-31-2024, 10:57 AM	#2
LogicalApex Brigadier General 2307 Rep 3,143 Posts Drives: 2020 BMW 530xe Join Date: Jul 2019 Location: Farmington, NY iTrader: (0) Garage List 2020 BMW 530xe [0.00]	I can't speak to the groaning noise as I haven't heard it. But it is possible I haven't listened for one either... That said, a jerking on acceleration at low speeds is common. It can happen on EV only mode as well so it isn't related to the engine engagement clutch. When I've asked BMW about this they said it is just a thing the ZF transmission does and isn't a problem. It isn't something I always experience, but I do experience it from time to time. BMW stressed that if there are any problems with the transmission it will throw codes and it hasn't done that yet. It has been covered on the forums from time to time as well. So far, my car has been otherwise fine over 50K miles and 5Y. I've owned it since new FWIW.
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12-06-2024, 08:32 PM	#3
d4700 Enlisted Member 18 Rep 38 Posts Drives: 2021 530e Join Date: Mar 2023 Location: Phoenix, Arizona iTrader: (0)	A quick update - I did a spill and fill with Fuchs 6008 fluid last week. Dropped about 4 liters and put exactly the same amount in, rechecked after a drive to get the fluid above 75C (thermostat opens), and the level was bang on (slow drips at 40C). Shift quality is marginally improved, but the soft groaning noise from 2-3 persists in EV mode. I may look into changing the filter as well at some point to see if this improves, but the noise hasn't gotten any worse at this point and doesn't impact driveability. I think I'm just overly sensitive!
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