Buffeting sound in rear of cabin
06-09-2018, 02:03 PM
#1
Senior Member
Thread Starter
Buffeting sound in rear of cabin
I know there’s been lots of discussion about the Acoustical glass for the front windows to alleviate wind noise. I don’t have too much of a problem with true “wind noise”up front, but I have noticed since I’ve had the car, almost a year, that there is some sort of buffeting sound that sounds like it’s towards the rear of the cabin, high up towards the roof. I noticed it the first time while traveling at 60-65 MPH, but have noticed it occurs at much slower speeds as well, if the radio is turned down. I would liken it to something flapping outside, but at a low pitch, almost like a thumping sound. Obviously there is nothing there except the roof rails and I assume it’s not them. I had crossbars on my ‘06 Highlander and they never made any sound whatsoever. I would expect my GLC to be just as quiet as that.
And BTW, I don’t think it’s anything mechanical at all. No whining or grinding, just a thumping sound like there’s a balloon flapping in the wind.
Any ideas?
And BTW, I don’t think it’s anything mechanical at all. No whining or grinding, just a thumping sound like there’s a balloon flapping in the wind.
Any ideas?
06-09-2018, 10:33 PM
#3
Senior Member
Thread Starter
No crossbars. I wondered if it could be the Pano moving at speed, but they did the Pano recall check when it was in for other work and said it was ok.
Also wondered about something aerodynamically wrong underneath or if the spoiler accessory would break up the wind flow over the lift gate. My Highlander had a built in spoiler. It’s a separate option on the GLC that I didn’t get, mainly because I didn’t like the the idea of it being added on as an accessory.
Also wondered about something aerodynamically wrong underneath or if the spoiler accessory would break up the wind flow over the lift gate. My Highlander had a built in spoiler. It’s a separate option on the GLC that I didn’t get, mainly because I didn’t like the the idea of it being added on as an accessory.
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bad habit (07-06-2020)
06-12-2018, 03:26 PM
#6
Senior Member
I've had this problem in other cars but not in my GLC300. Here are a few things I'd suggest based on my experience:
First, ask your dealer to perform service campaign LI46.35-P-062791, a re-programming of the power steering parameters. There's a known issue with the GLC300 steering rack. This fix has been effective for some problems with GLCs that involve vibration. I had a Subaru that had a terrible thrumming/vibration problem at high speeds and it turned out to be the steering rack on that car, too.
Second, check the pano roof at speed by opening/closing and then manually pushing on the panels at speed. You need to have someone else driving to do this properly.
Third, check tire pressure and be sure the wheels are properly balanced. Mercedes recommends 32 PSI cold all around unless running max vehicle load. Once you've done the pressures, ask the dealer to pull the wheels and confirm they are all properly balanced.
I would be interested to hear if you get this resolved, and how.
First, ask your dealer to perform service campaign LI46.35-P-062791, a re-programming of the power steering parameters. There's a known issue with the GLC300 steering rack. This fix has been effective for some problems with GLCs that involve vibration. I had a Subaru that had a terrible thrumming/vibration problem at high speeds and it turned out to be the steering rack on that car, too.
Second, check the pano roof at speed by opening/closing and then manually pushing on the panels at speed. You need to have someone else driving to do this properly.
Third, check tire pressure and be sure the wheels are properly balanced. Mercedes recommends 32 PSI cold all around unless running max vehicle load. Once you've done the pressures, ask the dealer to pull the wheels and confirm they are all properly balanced.
I would be interested to hear if you get this resolved, and how.
06-12-2018, 05:21 PM
#7
Senior Member
Thread Starter
I've had this problem in other cars but not in my GLC300. Here are a few things I'd suggest based on my experience:
First, ask your dealer to perform service campaign LI46.35-P-062791, a re-programming of the power steering parameters. There's a known issue with the GLC300 steering rack. This fix has been effective for some problems with GLCs that involve vibration. I had a Subaru that had a terrible thrumming/vibration problem at high speeds and it turned out to be the steering rack on that car, too.
Second, check the pano roof at speed by opening/closing and then manually pushing on the panels at speed. You need to have someone else driving to do this properly.
Third, check tire pressure and be sure the wheels are properly balanced. Mercedes recommends 32 PSI cold all around unless running max vehicle load. Once you've done the pressures, ask the dealer to pull the wheels and confirm they are all properly balanced.
I would be interested to hear if you get this resolved, and how.
First, ask your dealer to perform service campaign LI46.35-P-062791, a re-programming of the power steering parameters. There's a known issue with the GLC300 steering rack. This fix has been effective for some problems with GLCs that involve vibration. I had a Subaru that had a terrible thrumming/vibration problem at high speeds and it turned out to be the steering rack on that car, too.
Second, check the pano roof at speed by opening/closing and then manually pushing on the panels at speed. You need to have someone else driving to do this properly.
Third, check tire pressure and be sure the wheels are properly balanced. Mercedes recommends 32 PSI cold all around unless running max vehicle load. Once you've done the pressures, ask the dealer to pull the wheels and confirm they are all properly balanced.
I would be interested to hear if you get this resolved, and how.
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06-13-2018, 03:01 PM
#8
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GLC43, GTI, X3, Mazda3
Is the buffeting like the "helicopter effect" that you might hear if one window is down...usually in the back? I experienced that type of sound last weekend while driving my 43 with the front and rear driver's windows down slightly. I'm guessing I was in the 35-45mph range. That seemed odd to me with having 2 windows down, as it usually is an effect with a rear window down only. If this is the same sound you are experiencing, I'm theorizing it is because of the large pano roof, along with the GLC being so tight and solid with all the doors shut. If not the same thing, disregard and hope you figure it out.
06-13-2018, 09:32 PM
#9
Senior Member
Thread Starter
Thanks for the idea, Chrisk, but it’s not the helicopter effect you mentioned. I’ve had that in other cars too and this is much more muted than that. What I don’t understand is my GLC has no exterior accessories, so it seems like this is something that at least SOME other owners would notice. Maybe I’m the first and I’ll be able to find a solution for others who may notice it later.
07-02-2020, 02:38 PM
#10
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Hi Vaboy, Have you found the solution for your problem? I've got the same issue for some time now (buffeting sound from the left rear mostly above 60mph). Rear door has been adjusted. Rear hatch rubber stoppers replaced and adjusted. Problem still not fixed.
07-02-2020, 03:14 PM
#11
Senior Member
Thread Starter
Sorry h3660, but I never had any luck figuring out what the buffeting noise was, even though the lead MB service technician agreed he could hear “something”. They checked several things but couldn’t eliminate the sound. The only time it disappeared was on a trip to the beach when I had the lower rear storage compartment packed full, with two adults in the back seat as well. That convinced me it had something to do with the aerodynamics of that rear storage compartment when it is empty. I could never figure out what the culprit was in that area though. I guess I finally just got used to it and don’t notice it, not that it’s not still there!
07-04-2020, 10:00 AM
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Vaboy, thanks for the feedback. I will take my GLC into the Mercedes body shop and see maybe they can find a solution. I was thinking maybe its one of the hatch seals or the rear glass not fitted correctly. Maybe with your rear compartment fully loaded the distortion in the glass/body work closes the gap.
07-04-2020, 08:15 PM
#13
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19 GLC300 4M (lunar blue/black/black ash aluminum),17 GLE350 4M (selenite grey/ espresso/eucalyptus)
Vaboy, thanks for the feedback. I will take my GLC into the Mercedes body shop and see maybe they can find a solution. I was thinking maybe its one of the hatch seals or the rear glass not fitted correctly. Maybe with your rear compartment fully loaded the distortion in the glass/body work closes the gap.
07-06-2020, 01:48 PM
#14
Senior Member
Thread Starter
Let us know....
Vaboy, thanks for the feedback. I will take my GLC into the Mercedes body shop and see maybe they can find a solution. I was thinking maybe its one of the hatch seals or the rear glass not fitted correctly. Maybe with your rear compartment fully loaded the distortion in the glass/body work closes the gap.
