Common problem? Help diagnose please? M113 whining, high pitch squeeling engine noise
05-07-2018, 04:47 AM
#1
Common problem? Help diagnose please? M113 whining, high pitch squeeling engine noise
Hi everybody.
A bit of a mystery one for you today. Click on the attached video and listen to this.
This is my CLK430 4.3L V8 engine, with 310000 km (about 220000 miles). This engine noise used to only occur on startup, and would disappear after a short time. Now, it is making this kind of noise ALL the time. The pitch of the noise appears to be almost proportional to the air pressure/vacuum inside the intake plenium chamber (MAP). When the pressure difference is higher, the note is a higher note or pitch. The noise does not change intensity or octave in proportion to the speed of the car, or the RPM. The noise is not coming from the fan belt at all, and continues to make this same sound, even after removing the fan belt and after removing the electrical plug for the secondary air pump (at the front of the engine). It seems loudest at the rear right and front left sides of the top of the engine. I do not believe it is related to the cam shaft as engine rpm doesn't alter the sound.
Notice how the noise seems to stop a split second after the engine has stopped?
If you have experienced this kind of noise before, or you think you have a good idea of what this noise probably is, please let me know your thoughts, thank you.
A bit of a mystery one for you today. Click on the attached video and listen to this.
This is my CLK430 4.3L V8 engine, with 310000 km (about 220000 miles). This engine noise used to only occur on startup, and would disappear after a short time. Now, it is making this kind of noise ALL the time. The pitch of the noise appears to be almost proportional to the air pressure/vacuum inside the intake plenium chamber (MAP). When the pressure difference is higher, the note is a higher note or pitch. The noise does not change intensity or octave in proportion to the speed of the car, or the RPM. The noise is not coming from the fan belt at all, and continues to make this same sound, even after removing the fan belt and after removing the electrical plug for the secondary air pump (at the front of the engine). It seems loudest at the rear right and front left sides of the top of the engine. I do not believe it is related to the cam shaft as engine rpm doesn't alter the sound.
Notice how the noise seems to stop a split second after the engine has stopped?
If you have experienced this kind of noise before, or you think you have a good idea of what this noise probably is, please let me know your thoughts, thank you.
Last edited by MercedesOEM; 05-07-2018 at 05:23 AM. Reason: Video error
05-14-2018, 08:54 AM
#2
Further update
After listening to the noise, I have a suspicion that the breather hose that runs into the centre of the plenium is "whistling". I plan to disassemble this and take a look, and I have already ordered the replacement breather hoses and associated parts. Will continue to investigate.
10-15-2018, 12:47 AM
#4
Super Member
After listening to the noise, I have a suspicion that the breather hose that runs into the centre of the plenium is "whistling". I plan to disassemble this and take a look, and I have already ordered the replacement breather hoses and associated parts. Will continue to investigate.
