akbro93704

We took in our '03 ML55 to the dealer last Monday(21st) for new pads/rotors and a routine service. The engine had also been making a clicking/rattling noise at about 1500 RPM when the engine was cold, but it had done that since the car was new, so we figured it was normal but told the service advisor anyway. We got a call the day after we took the car in saying that they had to call the factory to see what the problem could be, which made zero sense to me, don't the mechanics know?? They had to wait for a response, and got one the next day(wed.) saying to not drive the car the problem could be serious. So the only thing the factory said that it could be was the timing chain. The dealer ordered the part, and it came in on Thursday, but they didn't have the stupid tool to change the timing chain, so they had to order that too and it's supposed to come in tomorrow. They say it's a three hour job. Is this really the problem??Has anyone else had problems with the timing chain? thanks

AMG4FUN

Bump....

Shifter

Is your ml under warranty? Odd they would go that route usually only open PTSS cases for warranty or unusual issues not a noise or such. But weird stuff happens.

In my experience I have never seen a timing chain on a 112/113 motor stretch or go bad that I can remember.
But that doesn't mean it can't happen.

AMG4FUN

No it is not.

This is a link to the noise I am hearing. I am wondering if it is the same.

I just replaced the idle pulley, as I initially thought I might come from that, but the noise is still there.

http://youtu.be/mcE-NB-j8VA

kered

See if you can pinpoint where the noise is coming from. Could be lifters that have collapsed. Take a stethoscope and see if the noise is more pronounced at the valve covers or from the front cover (be careful of moving parts and the belt)

AMG4FUN

OK, A couple of things. I pulled off the serpentine belt, to try and eliminate pulley noise. The noise is still there when turning on the engine.

Next step. I am almost 99% sure the noise is coming from the area of the air pump, which I guess is also where the timing chain is somewhat located. The noise does not seem to come from the valves, and definitely from the front of the engine.

Anything else I could do?

kered

112 and 113 where pretty common for the harmonic balancer to fail. The rubber insert breaks away from the pulley, and when this happens the pulley can rub against the timing cover thus making a horrible noise. I would inspect this area carefully, because if left too long the pulley will wear through the case, and then the fix becomes a whole lot harder.

AMG4FUN

It's definitely a possibility. I ran without the air pump, and the noise is still there. I'm taking the car in friday, and will post if they are able to diagnose the noise.

Also, not completely sure what to look for on the harmonic balancer, but will take a look. I found a few youtube videos of failed harmonnic balancers, and one sounded alot like my noise....

Ausmbtech

Timing chain issues are very very rare on the M112 and M113's. The rocker gear does tend to sound quite noisy with the bonnet up (rapid clicking). I have seen some timing chains get noisy, usually very obvious when cold or below 2000rpm. Never seen one break on these engines (they do on other engines) and the 2 Ive seen that have been quite worn have had prior missed services or low grade oil used and both stretched enough to bring the engine light on (cam position sensor)

First step is to remove the drivebelt as this eleminates a number of possibilities. If the dealer says it the chain then let them change it, it certainly wouldn't hurt.