M156 Engine Whistling
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W164 ML63 AMG W163 ML55 AMG X164 GL550
M156 Engine Whistling
[size=16px]Hi there ! I have a strange problem when i drive a few mile and when the engine is hot runing and stand next the car its whistling .. when i open the engine oil intake cap ( lot of air or gas coming out ) its stop the whistling . [/size]
[size=16px]Somebody can help ?[/size]
[size=16px]Somebody can help ?[/size]
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Joined: Jun 2014
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
The air/gas coming out of the oil filler cap is known as Blowby. Its exhaust gases that seep past the piston rings and into the crankcase. All engines do it to some extent, and much of that is recirculated through the intake system via a rebreather valve or Positive Crankcase Ventilation ("PCV") and reburnt in the cylinders. As a result, it keeps the pressure you are experiencing under control.
Depending upon engine age and health, I'd be looking at your PCV system to make sure its working properly as it appears you have too much pressure in the crankcase, hence the air is trying to escape in areas other than the PCV causing the whistling sound.
Time to take it to a decent shop if you're not confident in doing it yourself. From memory, these engines have a plastic cap on the back of the RHS valve cover that feeds those gases back into the inlet manifold.
You might have either too much blowby due to poor engine condition, or a blockage in the PCV system (or may be even both).
How many miles on the engine? Does it use oil? Do you change your oil frequently? Depending upon the answers to those, it might simply be that your engine is worn, allowing excess gases past the piston rings and into the crankcase.
Depending upon engine age and health, I'd be looking at your PCV system to make sure its working properly as it appears you have too much pressure in the crankcase, hence the air is trying to escape in areas other than the PCV causing the whistling sound.
Time to take it to a decent shop if you're not confident in doing it yourself. From memory, these engines have a plastic cap on the back of the RHS valve cover that feeds those gases back into the inlet manifold.
You might have either too much blowby due to poor engine condition, or a blockage in the PCV system (or may be even both).
How many miles on the engine? Does it use oil? Do you change your oil frequently? Depending upon the answers to those, it might simply be that your engine is worn, allowing excess gases past the piston rings and into the crankcase.
Last edited by BlackML550; Jan 27, 2024 at 04:46 AM.
