Knock on startup
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Senior Member
Joined: Feb 2005
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From: via Mulholland
2024 GLE63s
Knock on startup
When I start up the car after sitting for a couple of hours or more I can hear a faint but distinct knocking sound for about one second until the oil pressure builds up and it goes away.
Do you guys think this is a typical MB thing? In the old days, I could understand the lifters needed to "pump up" but on a new motor - it makes we wonder. It's a 2009, so this could not be related to the timing gear issue, right...?
Do you guys think this is a typical MB thing? In the old days, I could understand the lifters needed to "pump up" but on a new motor - it makes we wonder. It's a 2009, so this could not be related to the timing gear issue, right...?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
You are out of the chain sprocket trouble window.
There are basically 3 potential areas for rattle/knock in the engine. Hydraulic lifters, cam chain until under full hydraulic tension & slight piston slap until oil pressure is up & the engine warm with all clearances normalised due to ultra short skirt pistons.
Should this happen - No. But in reality it does. A lot of Benz V6 & V8 engines have the slightest cluck, cluck noise until warm. I would not worry about it but just monitor it & see that it does not get worse.
My previous car with an M112 V6 had a slight cluck, cluck when new that went away as mileage went up never to return. The present M272 is silent thusfar but only has 15,000 miles on it.
There are of course a number of accessories on the Poly V belt drive that make noises from time to time. I hate to say it but German engines have never been the quietest. But they are generally extremely durable.
There are basically 3 potential areas for rattle/knock in the engine. Hydraulic lifters, cam chain until under full hydraulic tension & slight piston slap until oil pressure is up & the engine warm with all clearances normalised due to ultra short skirt pistons.
Should this happen - No. But in reality it does. A lot of Benz V6 & V8 engines have the slightest cluck, cluck noise until warm. I would not worry about it but just monitor it & see that it does not get worse.
My previous car with an M112 V6 had a slight cluck, cluck when new that went away as mileage went up never to return. The present M272 is silent thusfar but only has 15,000 miles on it.
There are of course a number of accessories on the Poly V belt drive that make noises from time to time. I hate to say it but German engines have never been the quietest. But they are generally extremely durable.
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Joined: Nov 2007
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I drive the racism out of BadDebt. ;)
my m112 makes a clacking sound upon startup after a cold night...only for about 3 seconds. I now have 200,000 kms on it...not to worried until it makes a clacking sound while I'm driving....
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NO LONGER ACTIVE
Yep, both M112 engines I've owned did this. Our C240 has over 100K miles and it's fine, and the ML must have over 200K and is still going strong. I sold it 6 years ago at 90K, that guy put another 80K on it, and another guy who works at the local dealership bought it and has been driving it the last two years.
