M157 piston slap

[AlexM]

Hi All,

Now that the temperature has dropped to around 5 degrees, I've noticed that my car has a noticeable amount of what sounds like piston slap that lasts for a few minutes until the engine starts to warm up.

I know that the m157 isn't exactly a Lexus, but is this 'normal'?. Does the m157 use forged or hypereutectic cast alloy pistons? I know that clearances when cold are usually set a bit on the high side to allow for their greater coefficient of expansion. I guess the relatively short piston skirts don't help either.

Any info or opinions? Has anyone else noticed this?

Regards,
Alex

Sent from my ONEPLUS A5010 using Tapatalk

 

[AlexM]

Hi All,

Now that the temperature has dropped to around 5 degrees, I've noticed that my car has a noticeable amount of what sounds like piston slap that lasts for a few minutes until the engine starts to warm up.

I know that the m157 isn't exactly a Lexus, but is this 'normal'?. Does the m157 use forged or hypereutectic cast alloy pistons? I know that clearances when cold are usually set a bit on the high side to allow for their greater coefficient of expansion. I guess the relatively short piston skirts don't help either.

Any info or opinions? Has anyone else noticed this?

Regards,
Alex

Sent from my ONEPLUS A5010 using Tapatalk

Ok, it seems the m157 has cast pistons, so that theory is out of the window. I don't like the noises this engine makes really. Its is all less refined than you would expect from a Mercedes (even an amg!).

Noisy injectors, valvegear and now piston slap?.

Sent from my ONEPLUS A5010 using Tapatalk

 

[Psilonaught]

i must say mine also sounds quite "clicky" and mechanical when standing at the engine bay. I'm in the look out for a 97 CL600 V12, now THAT is silky...!

 

[zenman63]

Direct injection click but thats it.

 

[AlexM]

Maybe I'm just being too sensitive - the car certainly pulls well..

My dealer says that their senior technician, who came from MB Brooklands says that they are all quite noisy and there is some sample to sample variation. They insist that they didn't hear anyting wrong with my engine, but I get occasional tapping from a hydraulic element, the usual injector noise and now some slight piston slap when very cold.

 

[SteveWUK]

Mine can be fairly noisy just after start up and as you remark the sound at tick over when cold isn't exactly ''refined''
For what it's worth though I haven't noticed this get worse during the recent cold weather.