2017 GLC300 Whining noise when shifting 4th to 5th when cold
 

Hello everyone -

The very next day after purchasing our GLC300, we noticed a brief whining sound when first driving off under normal conditions, reaching speeds shifting from 4th to 5th gear. The sound would occur only once during the first drive. Only after sitting for a few hours, and remaining cold outside, would the problem reoccur each day. A call to the dealership offered the suggestion to allow a few break in miles. Now with 1,500 miles and with the problem still present - off to the service department we go. They confirmed the problem but have not identified the source other than suspect the transmission. We're now waiting for a regional MB Field Engineer to be assigned to the case for further diagnosis.

Has anyone had similar issues with a factory new GLC300?

Weird...I hope it gets figured out for ya soon.

If I was in your shoes I would trade for another Model.

Wanted you to get miles on it so you cannot return it and ask for another one. I would have asked for a different car. Now that you have many more miles on it you cannot without a lolt of complaining. Slick dealer

moved to X253 forum...

If I'm not mistaken we all have the same 9g gearbox. Can you video the noise you are hearing?

Thanks for the several replies. I found a video posted on YouTube with an identical sound and a similar problem description. The posting is three years old though and our GLC is a 2017. I would have thought that if there was a recurring issue, Mercedes would have incorporated a design fix by now. The video may be viewed here: One of the comments in this video suggest a Prop Shaft Bearing, another says its the Differential.

I think if either of these were defective, the dealer would have been able to identify the problem without having to escalate to MB factory engineering.
Meanwhile we're enjoying the loaner car and we are anxiously waiting for the MB engineer to arrive from New Jersey.

The W205 has a different transmission in this video than the the the GLC. The GLC has a9G while the w205 has a 7G. Dealer needs MB to figure out the problem. Hopefully they will get you an answer soon.

Oh dear that sounds horrible, but as dieseldoc already stated that is a totally different gearbox. Whilst it may be a similar issue (always difficult to tell from sounds) I don't think you can conclude it is a recurring issue. Ultimately it is a mechanical and electrical machine, things fail unfortunately. Best to just let the dealer/MB find out what it is.