Hi
I have just bought a 6 year old Mercedes A170 automatic from my local dealer. Fortunately they gave me a 12 month full Merc warranty on it.
The engine when warm makes a groaning/low humming noise which almost matches the engine revs. In other words a slight delay. It sounds like a big belt fighting for grip on a pulley or a kind of air pressure build up being slowly released. sounds almost like a trumpet noise but lower pitched. It is more noticeable when driving slowly accelerating away from traffic lights etc. This is intermittent and only happens when warm. Merc dealer has no idea what it could be & I have insisted that they take it for a thorough test drive this time (not just two miles like the last time). I have ruled out the Air-Con. They have suggested that it is some sort of belt tensioner mechanism that needs changing & they are doing that next Tuesday. But even the technician said it is probably not that causing the noise.
I have only had the car three weeks & it is driving me insane.
I am going to take my camera out and make a video recording.
I am in need of advise please on what it could be
Thanks in advance.
I have just bought a 6 year old Mercedes A170 automatic from my local dealer. Fortunately they gave me a 12 month full Merc warranty on it.
The engine when warm makes a groaning/low humming noise which almost matches the engine revs. In other words a slight delay. It sounds like a big belt fighting for grip on a pulley or a kind of air pressure build up being slowly released. sounds almost like a trumpet noise but lower pitched. It is more noticeable when driving slowly accelerating away from traffic lights etc. This is intermittent and only happens when warm. Merc dealer has no idea what it could be & I have insisted that they take it for a thorough test drive this time (not just two miles like the last time). I have ruled out the Air-Con. They have suggested that it is some sort of belt tensioner mechanism that needs changing & they are doing that next Tuesday. But even the technician said it is probably not that causing the noise.
I have only had the car three weeks & it is driving me insane.
I am going to take my camera out and make a video recording.
I am in need of advise please on what it could be
Thanks in advance.