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c300 Engine Whine upon Acceleration
#26
I have had a whine for 3 1/2 years which is only heard when the air-conditioner is on & only under light load. On a hot day ie 34'C it is not present.
The whine sounds very rpm dependent ie raises & lowers the pitch.
It takes about 40 seconds to disappear when the A/C is turned off but disappears immediately when the set point is lowered.
Sounds like a gas/ liquid throttling noise to me, not mechanical.
Any advice welcome.
The whine sounds very rpm dependent ie raises & lowers the pitch.
It takes about 40 seconds to disappear when the A/C is turned off but disappears immediately when the set point is lowered.
Sounds like a gas/ liquid throttling noise to me, not mechanical.
Any advice welcome.
Thanks very much
#27
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Join Date: Nov 2013
Location: NY
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2012 C63 AMG, 2009 C300 4matic
I notice it as well...
i ONLY get the noise when my AC is on and while accelerating. The noise correlates with the RPM of the engine.
Has anyone heard of a fix for this issue?
i ONLY get the noise when my AC is on and while accelerating. The noise correlates with the RPM of the engine.
Has anyone heard of a fix for this issue?
#28
Super Member
Here's a TSB i found on alldatadiy.com
Replacement of Refrigerant Compressor Belt Pulley Due to Noise Complaints If you receive customer reports in the above model vehicles of noises at the refrigerant compressor with air conditioning activated and deactivated, the cause could be a defective belt pulley or belt pulley bearing. The pulley and pulley bearing can be diagnosed and replaced with the compressor still installed in the vehicle by following the procedures below.
1. Locate the noise by duplicating the conditions under which the complaint occurred.
2. If there is also a cooling performance complaint, the noise could be caused by low refrigerant level, perform a Refrigerant Circuit Test as per SDS and follow instructions for corrective actions.
3. Before the belt pulley on the refrigerant compressor is replaced, verify that the following components in the belt drive are not the source of the noise and repair as required.
^ Alternator
^ Power steering pump
^ Guide pulleys / tensioner pulleys
^ Water pump
4. If there is a whining noise that is RPM-dependant which is present with the air conditioning on AND off and is determined to be caused by the tensioner pulleys, guide pulleys or refrigerant compressor, continue with step 5.
I would assume it's the alternator, power steering pump or water pump then.
Replacement of Refrigerant Compressor Belt Pulley Due to Noise Complaints If you receive customer reports in the above model vehicles of noises at the refrigerant compressor with air conditioning activated and deactivated, the cause could be a defective belt pulley or belt pulley bearing. The pulley and pulley bearing can be diagnosed and replaced with the compressor still installed in the vehicle by following the procedures below.
1. Locate the noise by duplicating the conditions under which the complaint occurred.
2. If there is also a cooling performance complaint, the noise could be caused by low refrigerant level, perform a Refrigerant Circuit Test as per SDS and follow instructions for corrective actions.
3. Before the belt pulley on the refrigerant compressor is replaced, verify that the following components in the belt drive are not the source of the noise and repair as required.
^ Alternator
^ Power steering pump
^ Guide pulleys / tensioner pulleys
^ Water pump
4. If there is a whining noise that is RPM-dependant which is present with the air conditioning on AND off and is determined to be caused by the tensioner pulleys, guide pulleys or refrigerant compressor, continue with step 5.
I would assume it's the alternator, power steering pump or water pump then.
Idler Pulley - Whining Noise - Page 1
Idler Pulley - Whining Noise - Page 2
Idler Pulley - Whining Noise - Page 3
#29
MBWorld Fanatic!
When it is occurring I lower the set point to make the A/C work harder & have the cabin a little cooler.
I really think it is a throttling of gas or fluid noise at a certain valve position. By opening the valve the throttling resonance disappears. Therefore I do not worry about it.
I have been told by an A/C mechanic that raising the gas pressure a little ie recharging may fix it. I have not bothered as it does not happen very often.
I would be interested to know the result if you follow through with the diagnosis.
John.