Shops quote $5,500–$8,000 for this one, and the quote usually isn't the ripoff, the job really is that big. Here's what's actually failing, what the correct repair involves, and the honest part: this is not a job I do in a driveway.
Mercedes built the 2005–2008 M272 V6 with a balance shaft idler gear made of a soft composite material instead of hardened steel. Over time the gear's teeth strip away, slowly at first, which is why the earliest sign is usually a subtle vibration at idle and low speed rather than a dramatic noise. As the teeth wear, the relationship between the crankshaft, balance shaft, and timing chain starts to drift, and the engine computer logs timing correlation faults.
Once enough material is gone, the chain no longer tracks where it should. You get rattle, rough idle, and persistent timing codes that no sensor replacement will fix, because the problem is mechanical, buried in the front of the engine. This is one of the most documented failures in the Mercedes world; affected engines fall in a known serial-number range, and if your V6 is from these years, it's worth confirming.
Left alone, the end game is the chain jumping teeth. On an interference engine like the M272, a jumped chain means pistons meeting valves, and what started as a gear replacement becomes a cylinder head rebuild or a replacement engine. Catching it at the vibration-and-codes stage is the difference between a big repair and a catastrophic one.
If your Mercedes-Benz is doing any of these, this is the likely cause:
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See how that range compares across Mississauga, Oakville, Milton, Brampton and Etobicoke in the GTA Repair Price Index, honest shop & dealer ranges for the jobs people actually get done.
Balance Shaft Idler Gear & Timing Chain Replacement is on my published list of jobs I turn down. It needs a hoist, a press or a machine shop, and I work out of driveways with hand tools. That list is public on my trust page. I'd rather lose the job than learn it on your engine, and you should be suspicious of anyone who says yes to this over the phone.
So here's what I can genuinely do for you, holding a $5,500–$8,000 quote. Both are real, both are flat-priced, and both are worth more than a bad yes.
Before you spend $5,500–$8,000, have someone independent confirm that's actually what's wrong. This is a diagnosis, not the repair, no hoist, no lift, nothing comes apart. I scan it, test it, look at it with you, and tell you straight whether their diagnosis holds up. If it does, I say so and you go pay them with confidence.
Book the second opinion →At $5,500–$8,000 on a car that might be worth not much more, plenty of people replace instead of repair, that's a completely reasonable call. If that's where you're heading, get the next car measured before you hand over money: 150 published points, at the seller's location, written report the same day.
Book a pre-purchase inspection →Tell me what you've been quoted and what the car is doing. $100–$250 flat, at your location, and you get a straight answer either way.
Rather just have the quote read? The free quote check tells you whether the number is in line, no visit needed.
Jobs on this car that ARE mine:
Not so you can do it yourself, so you can tell whether the shop quoting you understands the job:
That's the job. It's why this one belongs on a hoist instead of in a driveway, and it's why $5,500–$8,000 usually isn't a ripoff, it's a big repair honestly priced. What's worth checking is whether that's really what your car needs.
Get the diagnosis confirmed firstPlain version: Balance Shaft Idler Gear & Timing Chain Replacement needs equipment a driveway doesn't have, a hoist to get under it properly, a press or a machine shop for the parts that come out, and a controlled space for an engine or gearbox that's in pieces for days. I work out of driveways with hand tools. That's not false modesty, it's the published limit of what I take on, and it's listed on my trust page alongside the warranty.
What that means for you: this page is here to tell you what's failing and what it should cost, so you walk into a shop knowing the job instead of nodding at a number. And if you want that number checked before you pay it, that part I can do, $100–$250 flat, at your location.
The wear only goes one direction. Every kilometre, the gear loses a little more tooth material, and the margin before the chain jumps gets smaller. A jumped chain on this engine bends valves, that turns a major repair into an engine-out rebuild costing multiples more. If you have the vibration and the codes, the clock is already running.
The failure-prone gear went into 2005–2008 production. If your V6 falls in that window and you have idle vibration plus timing correlation codes, the odds are high. We can confirm with a scan and inspection at your home before committing to the full repair.
Absolutely, and any honest mechanic will tell you the same. The chain has been running on a worn gear, the labour to get there is already paid, and chain, tensioner, and guides are a fraction of the job cost. Doing it all at once means you never open this engine up twice.
No. Balance Shaft Idler Gear & Timing Chain Replacement is on my published list of jobs I turn down, it needs a hoist, a press or a machine shop, and I work out of driveways with hand tools. I'd rather lose the job than learn it on your engine.
Two things, and both are real. A second-opinion diagnostic at your car, $100–$250 flat, at your location, so somebody independent confirms that's actually what's wrong before you commit to a $5,500–$8,000 repair. And if you're weighing replacing the car instead of fixing it, a pre-purchase inspection on the replacement, $149–$399 flat, at the seller's location.
Because the useful part isn't the wrench. It's knowing what's actually failing, what the correct repair involves, and that shops quote $5,500–$8,000 for it, so you walk in knowing the job instead of nodding at a number. If you want that number checked before you pay it, that part I can do.
Send it over for a free second opinion. I'll tell you straight what the job actually involves, and if their quote is fair, I'll tell you that too.
Get a Free Second OpinionOther makes:
I'm not the guy who does this repair. I'm the guy who tells you whether you actually need it, before you spend $5,500–$8,000. Second opinion at your car, $100–$250 flat, in Mississauga, Oakville, Milton, Brampton and Etobicoke.
Book a Second Opinion Inspect a Replacement CarYour options on this one