Harmonic Balancer Defect Investigation by NHTSA
 

FYI -

NHTSA Action Number : PE03058 NHTSA Recall Campaign Number : N/A
Make : MERCEDES BENZ Model: ML320
Manufacturer : MERCEDES-BENZ USA, LLC. Year : 2000
Component : ENGINE AND ENGINE COOLING:ENGINE:GASOLINE:BELTS AND ASSOCIATED PULLEYS
Date Investigation Opened : December 17, 2003
Date Investigation Closed : Open
Summary:
ODI HAS RECEIVED 35 REPORTS OF ENGINE CRANKSHAFT PULLEY HARMONIC BALANCER FAILURE ON THE SUBJECT VEHICLES EQUIPPED WITH M112 OR M113 ENGINES. THE M112 SERIES IS MERCEDES-BENZ'S FIRST EVER PRODUCTION V6 ENGINE AND ITS MODULAR DESIGN ALLOWS IT TO SHARE MANY COMPONENTS, INCLUDING THE ENGINE CRANKSHAFT PULLEY HARMONIC BALANCER, WITH THE M113 SERIES V8 ENGINES. THE M112 AND M113 ENGINE CRANKSHAFT PULLEY PROVIDES ACCESSORY POWER VIA A SERPENTINE BELT. THE COMPLAINANTS ALLEGE THAT ENGINE CRANKSHAFT PULLEY FAILURE CAUSES LOSS OF POWER STEERING ASSIST WHICH MAY INCREASE THE RISK OF A CRASH. A PRELIMINARY EVALUATION HAS BEEN OPENED TO ASSESS THE SCOPE AND SAFETY CONSEQUENCES OF THE ALLEGED DEFECT.

Filed report yesterday with NHTSA
 

My dealer found cracks in the rubber component of the harmonic balancer, while my 1998 ML-320 was in for a Mass Air Flow sensor replacement at 57,435 miles ($512), and recommended it be replaced before it failed completely. Replacement only took about an hour and cost $239. I'll be more relaxed now on trips not having to worry about the harmonic balancer coming apart, with all of the safety issues; costly repairs; and inconvenience this would entail. I reported the failure to NHTSA through their web site. If they get enough reports this repair cost may be refunded.

Harmonic Balancer
 

I had the exact same problem as Tom at 70000 miles. Dealer replace it for $90.00 ( labor only MB paid for the part )

Harmonic Balancer
 

Correct me if I am wrong but I believe MB has a bulletin on this one that dates back a year or two. I had mine fixed during the warranty period not requesting to have it done, an automatic replacement triggered by a service bulletin I believe...