SL55/63/65/R230 AMG: Knock coming from under rear end
#1
Knock coming from under rear end
Hello guys, i purchased a stock SL55 02', 150k kms in january, i did some things (ic pump, soft trunk close, battery leakage from teleaid), but now i would like to take care of this weird sound.
Car is running perfeclty fine i guess, engine and transmission, abc ok. I can hear a knock coming from under and behind the seat, not from the trunk. It's like something hitting the frame with a little hammer, only when i am turning. No sound when i ride on a bump, no sound when i brake or accelerate (i think). When i go to the left then to the right, clunk. Another thing i noticed, when i stop the engine after i drive of atleast 20min, i can hear this same sound (i guess) under the car. I can hear it clearly. It's like hot metal cooling down after a ride if you know what i mean but loud. Is is normal ? I could make a video if needed.
I thought of a relay (if there is) inside the end of the gearbox, of something moving freely but i have to go under the car to check this.
Thanks for your help !
Max
Car is running perfeclty fine i guess, engine and transmission, abc ok. I can hear a knock coming from under and behind the seat, not from the trunk. It's like something hitting the frame with a little hammer, only when i am turning. No sound when i ride on a bump, no sound when i brake or accelerate (i think). When i go to the left then to the right, clunk. Another thing i noticed, when i stop the engine after i drive of atleast 20min, i can hear this same sound (i guess) under the car. I can hear it clearly. It's like hot metal cooling down after a ride if you know what i mean but loud. Is is normal ? I could make a video if needed.
I thought of a relay (if there is) inside the end of the gearbox, of something moving freely but i have to go under the car to check this.
Thanks for your help !
Max
#2
SPONSOR
iTrader: (4)
Join Date: Dec 2019
Location: WWW.BENZNINJA.COM
Posts: 2,674
Received 843 Likes
on
653 Posts
WWW.BENZNINJA.COM
Hello guys, i purchased a stock SL55 02', 150k kms in january, i did some things (ic pump, soft trunk close, battery leakage from teleaid), but now i would like to take care of this weird sound.
Car is running perfeclty fine i guess, engine and transmission, abc ok. I can hear a knock coming from under and behind the seat, not from the trunk. It's like something hitting the frame with a little hammer, only when i am turning. No sound when i ride on a bump, no sound when i brake or accelerate (i think). When i go to the left then to the right, clunk. Another thing i noticed, when i stop the engine after i drive of atleast 20min, i can hear this same sound (i guess) under the car. I can hear it clearly. It's like hot metal cooling down after a ride if you know what i mean but loud. Is is normal ? I could make a video if needed.
I thought of a relay (if there is) inside the end of the gearbox, of something moving freely but i have to go under the car to check this.
Thanks for your help !
Max
Car is running perfeclty fine i guess, engine and transmission, abc ok. I can hear a knock coming from under and behind the seat, not from the trunk. It's like something hitting the frame with a little hammer, only when i am turning. No sound when i ride on a bump, no sound when i brake or accelerate (i think). When i go to the left then to the right, clunk. Another thing i noticed, when i stop the engine after i drive of atleast 20min, i can hear this same sound (i guess) under the car. I can hear it clearly. It's like hot metal cooling down after a ride if you know what i mean but loud. Is is normal ? I could make a video if needed.
I thought of a relay (if there is) inside the end of the gearbox, of something moving freely but i have to go under the car to check this.
Thanks for your help !
Max
maybe your transmission mounts/suspension
there are some mounts everywhere on this car that must be replaced especially if your car is a 2002
#3
I'm in the midst of troubleshooting what I think is the same noise on my 03 SL55 w 33k mi. It's a faint knocking—a slightly metallic noise coming from behind the seats either under the car or behind the rear bulkhead. I initially thought it was a tick not unlike an exhaust cooling but it's too rounded a sound and mine is also rhythmic (about every 20 secs). I'll hear it for awhile after shutting off the vehicle, maybe up to an hour. I suspect it makes noise while i'm driving or when the car is on, it's just not as apparent with engine and road noise going on.
I had the car up on my home lift, immediately after driving and isolated the noise to this spot:
![Knock coming from under rear end-f8vyo2k.jpg](https://mbworld.org/forums/attachments/sl55-amg-sl63-amg-sl65-amg-r230/439379d1683239935t-knock-coming-under-rear-end-f8vyo2k.jpg)
It's coming from behind that heat shield…
My indy mech has not had time to inspect yet but I suspect it's part of the ABC system as there's a valve block where lines run to.
I had the car up on my home lift, immediately after driving and isolated the noise to this spot:
![Knock coming from under rear end-f8vyo2k.jpg](https://mbworld.org/forums/attachments/sl55-amg-sl63-amg-sl65-amg-r230/439379d1683239935t-knock-coming-under-rear-end-f8vyo2k.jpg)
It's coming from behind that heat shield…
My indy mech has not had time to inspect yet but I suspect it's part of the ABC system as there's a valve block where lines run to.
#4
I'm in the midst of troubleshooting what I think is the same noise on my 03 SL55 w 33k mi. It's a faint knocking—a slightly metallic noise coming from behind the seats either under the car or behind the rear bulkhead. I initially thought it was a tick not unlike an exhaust cooling but it's too rounded a sound and mine is also rhythmic (about every 20 secs). I'll hear it for awhile after shutting off the vehicle, maybe up to an hour. I suspect it makes noise while i'm driving or when the car is on, it's just not as apparent with engine and road noise going on.
I had the car up on my home lift, immediately after driving and isolated the noise to this spot:
![](https://i.imgur.com/f8VYo2k.jpg)
It's coming from behind that heat shield…
My indy mech has not had time to inspect yet but I suspect it's part of the ABC system as there's a valve block where lines run to.
I had the car up on my home lift, immediately after driving and isolated the noise to this spot:
![](https://i.imgur.com/f8VYo2k.jpg)
It's coming from behind that heat shield…
My indy mech has not had time to inspect yet but I suspect it's part of the ABC system as there's a valve block where lines run to.
#5
Mine is definitely persistent not dynamic. I thought it might be the same as yours because yours is evident after the car is off while no components should be moving. I also thought it was a tick at first but the more I isolated it, realized it wasn't.
If you get a chance, next time you drive and park, pop your head under the car in front of the rear driver's side wheel. It wasn't until I got a lift that I pinpointed the sound. It initially sounded like it was behind the passenger seat. I had an ABC flush not too long ago and everything was in spec but it might be the valve block at the very initially signs of going.
If you get a chance, next time you drive and park, pop your head under the car in front of the rear driver's side wheel. It wasn't until I got a lift that I pinpointed the sound. It initially sounded like it was behind the passenger seat. I had an ABC flush not too long ago and everything was in spec but it might be the valve block at the very initially signs of going.
#6
So i tried many things today. I rode about 15 minutes then i stopped and recorded this the noise :
The noise is in reality stronger than what you can hear on the video. The tick can be heard every 6 sec, the more i wait the more it takes time, and stop 15 minutes after turning off the engine. Then i removed the two fuses that i believe are the ones used for the ABC system, no change, then i removed the two fuses of the gearbox, no change too. Next time i will disconnect the auxiliary battery, it be will clear if it's something related to some actuators or not. Abc fluid level is ok, but i don't have dipstick for the oil tranmission. When riding the car, i can hear the little noise when i brake hard or accelerate a bit. I know i have a little leakage coming from the gearbox cover i believe, i think i have to change the seal.
#7
So, i disconnected the auxiliary battery and i still have this noise, maybe i should try to disconnect the primary battery but i think it's only used for the starter. Veryyyyy weird