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2Addicts | BMW 2-Series forum Technical Topics Mechanical Maintenance and TSBs: Break-in | Oil & Fluids | Servicing | TSB Auto 8HP45 - Transmission Whine

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      06-10-2020, 06:14 PM   #1
abcfgh
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Auto 8HP45 - Transmission Whine

Hi, I have an M235i with the ZF 8-Speed Auto and a bit of transmission whine (I'm guessing). I've done a bit of researching around the issue of the transmission whine and it seems to be an issue with these cars, particularly when driving hard. I know that the torque ratings of the 8HP45 transmission (handles 450 Newton Meters) are really at the limit of what the N55 or even the N20/26 engines produce torque wise.

The car is 100% stock apart from the ER charge pipe. It's at 65k miles.

If driving normally you won't hear it. If driving at 8/10th's you won't hear it. If you're driving at 9 or 10/10th's, you might hear it then. It is not speed dependent and appears to do more with load/acceleration. I've also noticed it seems to particularly come about when cornering at very high g's and accelerating hard out.

Sounds exactly like this....


Any ideas? Any reputable shops which have done fluid swaps on a ZF 8-speed before? I don't have much trust in shops or dealers in general as I find most things end up not being done right. I don't have any place to work on it.
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      06-10-2020, 06:29 PM   #2
abcfgh
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I am wondering if the Transmission Fluid level is low. I guess I'm also asking for if there is a HIGHLY reputable shop that specifically services these ZF transmissions and has a lot of experience doing so.

I found this to be especially helpful. At the same time, I don't think any shops are going to know how to properly check the level of fluid in the trans or even change it properly unless they have done it at least a few times before. Every shop I've spoken to says they've never done one before on an 8HP even if they claim to specialize in BMW's....


Last edited by abcfgh; 06-10-2020 at 06:44 PM..
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      06-11-2020, 01:35 AM   #3
abcfgh
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The procedure seems simple enough, but I am concerned about how much fluid should be added and when. If there is an external cooler, which are cars of course have, there is a thermostat which opens up at 70 celsius. And according to the video above and another video by Meyles (posted below), we should then overfill by 0.5 liters or drive and then fill it up again? I'm slightly confused. Can someone explain? Is there a definitive guide on how much to fill/when?

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      06-12-2020, 09:09 AM   #4
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The fill is done in 3 steps. The first step is when the transmission is empty and you're replacing the fluid and the filter. The transmission is run through the gears as shown. The second fill is then performed. Why? Running the transmission through the gears gets the new fluid properly distributed throughout the transmission. Then the car is driven for about 10 miles and the fluid level rechecked and topped off as required. It's complicated but hey, it's a modern car.
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      06-17-2020, 06:51 AM   #5
123Britt
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Change the Fluid at Half Life

I changed my Fluid with Lifeguard 8 at 50K miles following the ZF video using my Foxwell to monitor temps. Installed the ZF Pan Kit with filter.

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The pan has a standoff pipe which holds the fluid at a specific level .
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Hardest part is filling the pan once the temps reach the lower range temp.
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Many post on this topic. ZF says change the pan and fluid at your mileage.

https://aftermarket.zf.com/go/en/aft...on-oil-change/

Last edited by 123Britt; 06-17-2020 at 07:01 AM.. Reason: Link
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      06-19-2020, 05:30 PM   #6
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What about overfilling to compensate for closed thermostat for the oil cooler? Thoughts?
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      07-07-2020, 08:25 AM   #7
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You have two choices really: trust a shop, or figure it out on your own. I'd vote for #1 here. But hey, what could possibly go wrong with learning as you go?
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      01-18-2021, 03:53 PM   #8
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Quote:
Originally Posted by MarcoZandrini View Post
The fill is done in 3 steps. The first step is when the transmission is empty and you're replacing the fluid and the filter. The transmission is run through the gears as shown. The second fill is then performed. Why? Running the transmission through the gears gets the new fluid properly distributed throughout the transmission. Then the car is driven for about 10 miles and the fluid level rechecked and topped off as required. It's complicated but hey, it's a modern car.
its actually 4, youre supposed to fill the new pan until it drips from the fill plug, then start the engine, and immediately refill the pan because as the pump starts pumping, you want to ensure its sucking fluid and not air. fcp euro and others miss this step but you can see it on both ISTA and most ZF instructions if you look carefully
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      01-18-2021, 06:20 PM   #9
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FWIW my 2004 E46 would "whistle" when it got low on fluid.
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      03-16-2022, 08:49 AM   #10
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Did you manage to figure out what went wrong? I'm experiencing the exact same problem (but much lower volume) in my 2015 M235i as well (Canada Spec). Feels like a supercharger whine. I'm hoping its not a timing chain or turbo. If it's just fluid then it shouldnt be too hard to handle.
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      05-28-2023, 03:15 PM   #11
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Nope, did a transmission fluid and filter service. Nothing changed. It's steadily gotten worse. Car has 130k miles nearly now. Pretty sure something is wrong with the trans. I just back off as soon as I hear it.
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      08-07-2023, 09:06 AM   #12
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To revive this thread, I'm going through something similar myself as I'm planning on getting my transmission oil changed.

There seems to be one step everyone seems to be missing, and even zf qualified garages don't seem to mention.
Any car with an oil thermostat will need an overfill of 0.5ltrs once temperatures hit 75°c.

I've actually just emailed zf, and attached a screenshot of their reply.
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      11-03-2023, 12:36 AM   #13
abcfgh
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Quote:
Originally Posted by Itr123 View Post
To revive this thread, I'm going through something similar myself as I'm planning on getting my transmission oil changed.

There seems to be one step everyone seems to be missing, and even zf qualified garages don't seem to mention.
Any car with an oil thermostat will need an overfill of 0.5ltrs once temperatures hit 75°c.

I've actually just emailed zf, and attached a screenshot of their reply.
You have a good point. Did your whining get any better after you changed the fluid? Also how exactly do you overfill by 0.5 liters. Wouldn't it just pour out of the drain hole? Not quite understanding.
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      11-03-2023, 01:15 AM   #14
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Quote:
Originally Posted by abcfgh View Post
You have a good point. Did your whining get any better after you changed the fluid? Also how exactly do you overfill by 0.5 liters. Wouldn't it just pour out of the drain hole? Not quite understanding.
It was something I emailed zf direct to get a definitive answer to.

Their reply was as follows...

'Once the vehicle has reached 75 Degrees this will then open the oil cooler, the transmission then needs filling with another 0.5L of oil to fill the void that has been then passed through the cooler.'
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