OM606 turbo: 'Whirring' noise @ 2000-2200 rpm - PeachParts Mercedes-Benz Forum

scott19_68 · #1 03-23-2007, 08:12 AM

I've search these forums for something that matches my symptoms but I feel I am not using the correct verb to describe the sound I am hearing. I used the term 'whirring' but more descriptive would be 'like an old washing machine'. It seems to be more noticeable when the engine is not a full operating temperature and is only fairly faint. The turn up the radio 'repair' method works great on this one!

One condition to produce the odd noise is that the engine has to be under load - revving it in park/neutral up to 2200 rpm does not produce the sound. From the driver's seat I swear it is coming from the injection pump side of the engine but I cannot rule out the turbo. There seems to be slightly less power in this RPM range and if I try to accelerate quickly from ~2000 rpm, there is a definite pause and even a slowdown before the engine revs up.

Just to get some probable follow-up questions out of the way:

1) Timing - never had it checked
2) Timing chain - engine has only 115k mi
3) MAF sensor - original since I bought the case (20k mi ago)
4) IP - new delivery valve O-rings, otherwise never had it checked
5) Injectors - never had them checked - idle is slightly uneven when warm
6) Engine - burns pratically no oil - Rotella-T 5w40 + filter every 5k miles

Any help is greatly appreciated.

WINGAS · #2 03-23-2007, 08:59 AM

Purge and timing check. Simple tune up stuff.

TMAllison · #3 03-23-2007, 09:37 AM

Try dropping the serp belt on a cold engine and running it for 30 secs to rule out if is accessory pulley or tensioner related.

Not burning alternative fuels right? I notice when burning B99 my turbo is much more active than on D2.

aklim · #4 03-23-2007, 07:29 PM

I think I have that sound too when it spools up.

BioPOWER · #5 03-23-2007, 11:56 PM

If it's only a 'whirring' sound, my guess is it's your turbo operating normally. Mine kicks in right around 2000rpm, but I can only hear it with a window down.

Second guess is a serpentine belt tensioner (if the noise is more of a 'roar').

85chedeng300D · #6 03-24-2007, 11:02 AM

At 2000 to 2200 RPMs, sound normal to me. My 617 turbo does it especially when upshifting between gears or whenever it's coasting or while letting go of the accel. pedal. Does it have an ARV? Try to disconnect and plug the ARV vacuum hose and drive and listen.

scott19_68 · #7 03-24-2007, 01:51 PM

I performed a purge a few months ago - no change. Timing advance is controlled electronically on these turbo 606's, correct? Is timing change stretch the only way for it to be off from the factory setting?

I took a look at the serpentine belt and it is pretty loose - I can deflect it about an inch with moderate thumb pressure. The tensioner spring is encased in a rubber sleeve so it is hard to tell if it is broken.

What is an ARV? If that is synonymous with a wastegate valve? If rev it up to +3k RPM and let off the accelerator I do hear the hissing of boost escaping the wastegate so that is operating properly.

It seems the noise is getting progressively worse in the past few months. What kind of sound does a loose timing chain tensioner and/or worn upper chain guide sound like?

TMAllison · #8 03-24-2007, 02:03 PM

Try dropping the serp belt and see if the sound disappears.

If the spring breaks you will know it. Big Bang....No tension. Belt jumping and making noise.

85chedeng300D · #9 03-24-2007, 02:04 PM

ARV: Air Recirculating Valve, located just forward of the air intake manifold coming from the air tube from the turbo, and there should be a tiny vacuum hose attached to it.

Wastegate valve is at the bottom of the turbo and the should be a thick rubber hose attached.

I don't know much about the timing chain noise but if it's too lose enough to make noise, it gonna be obvious and alarming, I guess it's going to sound like a loud clicking sound from inside the engine and not a whine sound.

Hatterasguy · #10 03-24-2007, 02:08 PM

Its probably the serp belt, or something related to that.