OM603 timing chain sound at the valve cover
 

Hi, please watch my video on youtube http://www.youtube.com/watch?v=7f1BXhOkfJI where I use an auto stenoscope attached to an extermal mic on a video camera.

I've already replaced the water pump as indicated in my previous post. I've also replaced the chain tensioner located above the water pump. It came with the car when I bought it so I decided to go ahead and pop it in. I couldn't tell the difference btw except that the old one was probably stiffer.

Now my question is about the sound that you can hear from the valve cover where the timing chain sprocket is. I've seen another video of same car and it sounded the same.

However, I'm concerned that something is wrong as I don't have any basis for a proper sounding engine. I'm planning to open the valve cover at some point and do valve adjustment but not until I make proper wrenches.

Please let me know what you think.

Is the vacuum pump original?

Here's something I wrote in a thread about a 1987 300D:

Also note that these valves don't adjust like the OM616 / OM617, they're hydraulic.

Interesting. I'm going to be removing that this weekend then :) But you think the sound travels upwards from the pump?

BTW this is insane. I just posted this thread. And now it shows up second item in google?

BTW You can tell I'm really bored at work, can't you?

... and we wonder why our jobs are being outsourced to India.

;)

Thanks for pointing out about the valves. I'm getting a little bit of blowby and some oil in the intake so could it be that those hydraulic bucket tappets are bad? Valve stem seals? Timing chain stretch?

I'm in the process of replacing mine (just need funds). It hasn't made a sound yet, but I think I'd sleep better with a new one.

You could always try listening to the pump with your stethoscope. Have you had any trouble turning the car off (or other vacuum related problems)?

Maybe someone more experienced could chime in with other probable culprits. I'm not sure what kind of service interval is on the timing chain or rails, or if it is common to have those parts fail.

Did this sound appear right after you replaced the water pump?

Our company did that and now I'm bored cause these guys require twice as long to come up with correct code/fix/enhancement as it did before. So I'm idling in a sense. My brain though cannot slowdown and needs constant stimulation... :D

I have no vacuum problems with the car. I think I've listened to the pump before but did not record. I'll go through records and see if it was replaced. Like some people said it's better to know it's new. The car has 260K miles on it. Dunno if the engine is original. Better be safe than sorry.

The sound was always there - in the video it's before I replaced the water pump. I still have a ratcheting noise from the fan which I'm going to post another dedicated thread about.

I think they said 150K for timing chain. Going to check the stretch of it now that I know I don't need to do valve adjustment on the car. I have the new gasket so I'll pop the valve cover.

150K miles for a Mercedes diesel double-row timing chain sounds very conservative. If the timing shows that the chain hasn't stretched/sprockets worn, I'd leave it alone. OTOH, a stretched chain could be hitting something, could have worn the guide rails, etc.

I thought I had a timing chain rattle too. It turned out that my belt tensioner
shock absorber was in need of new rubber bushings. Noise gone. Look for the cheapest thing first!