113 Engine Noise

[Capp]

Does anyone have any information or experienced the following engine fault on a 2001 CL500.

113 engine sounds fine when cold but when it warms up there is a knocking noise more noticable at idle.

There were no prevoius engine noises or problems it happened instantly.
If I let it cool down it's quiet again at first.

When driving with the windows closed you cannot hear it but when I stop it's very loud.

I suspect at this stage it's from the engine but not 100% sure.

 

[steve333]

Does anyone have any information or experienced the following engine fault on a 2001 CL500.

113 engine sounds fine when cold but when it warms up there is a knocking noise more noticable at idle.

There were no prevoius engine noises or problems it happened instantly.
If I let it cool down it's quiet again at first.

When driving with the windows closed you cannot hear it but when I stop it's very loud.

I suspect at this stage it's from the engine but not 100% sure.

Have any warning messages appeared on the dash?(best to get the car checked/fault codes read on star diagnostics).

 

[Capp]

No faults appear and drives perfect, just the noise when warm.

 

[steve333]

No faults appear and drives perfect, just the noise when warm.

I would still get it looked at just in case it developes in to something more.

 

[Capp]

What do you suggest a main dealer or an independant specialist. Do you think MB would contribute to a car that old if it turns out to be a major engine fault. 2001 year 55,000 miles, should not really happen to a car like that.

 

[Coggers]

Unfortunately, engines do sometimes fail prematurely.

I suspect at this stage it's from the engine but not 100% sure.

If the speed of the knocking changes as you increase the revs of the engine, then its more likely to be linked to the engine (though not 100% of course). If the speed of the knocking increases as the wheel speed increases, rather than the revs, then its more likely to be linked to the other side of the transmission. I know this sounds simple, but its something that people overlook sometimes.

 

[GadgetBoy]

At the lights try this.

Slip the gearbox into N. Does the noise go away or change?
Switch the A/C off. Does the noise go away or change?

 

[steve333]

What do you suggest a main dealer or an independant specialist. Do you think MB would contribute to a car that old if it turns out to be a major engine fault. 2001 year 55,000 miles, should not really happen to a car like that.

My choice would be a good independant mb specialist,to answer the 2nd part of your question,as your car is well out of the 3 year warranty period any engine fault would not be covered but hey it might turn out to be something simple,good luck.

 

[JonathanC250]

Have you had the oil changed recently?

The oil used could have been too thin? Just a guess!

 

[mercedescl500]

Here's a thought, maybe its your ABC Tandem pump main pulley bearing on the way out. If you don't have a warranty you could be facing at least a 1k bill to remedy the problem. Sometimes the pump can get noisy but still able to make pressure, its the pulley bearing which can go bad. Unfortunately you would have to change to pump if the noise is coming from there. HTH