Mercedes M272 and M273 Balance Shaft Problem

#Which Mercedes models and years are affected (W203, W211, W164, W221)

Mercedes never defined this problem by model year. It defined it by engine serial number, in one bulletin, with two numbers. An M272 V6 is in range if its serial is 468993 or lower. An M273 V8 is in range if its serial is 088611 or lower. Engines built past those numbers got the corrected gear material at the factory.

That boundary comes from Mercedes-Benz DTB S-B-03.30/08, first issued August 23, 2007 and revised repeatedly through 2009 as the applicable model list was amended. Revision 08i of April 23, 2009 is the copy that circulates publicly, and it carries these serial numbers, the wording quoted below and the full repair procedure. Everything you read online about years and production months is an approximation of those two numbers.

Mercedes writes the cutoffs as 2729..30 468993 and 2739..30 088611. The dots stand in for variant digits; the six numbers on the end are the serial you compare. It is stamped into the block, but on most of these cars you will not see it without pulling intake plumbing. The quickest route is usually a Mercedes dealer parts counter, which can often look it up from your VIN. Send us that number, or the VIN, and we will tell you what it means and what the job costs on your chassis.

The serial range works out to roughly 2005 through early or mid-2007 production, which shows up as 2005-2007 cars plus a few early 2008 builds. The bulletin gives serial numbers, not a date, so treat any changeover date you read as an estimate. The 3.5L M272 also went into the gasoline Dodge Sprinter 2500 and 3500 for 2007 and 2008. The bulletin does not list the Sprinter, so treat that as unconfirmed and check the serial.

#M272 and M273 balance shaft replacement cost

These are estimates for an independent European specialist using genuine Mercedes parts. Members take 5 to 15 percent off labor depending on tier, roughly $200 to $950 on a job this size. Your number comes from a written estimate after diagnosis.

What swings the number is which engine you have, then which chassis. Mercedes' engine removal times for the V6 run 6.0 to 11.8 hours across the affected models, and that spread is the biggest variable on an M272 job: rear-drive W203 and W211 sedans at the cheap end, 4MATIC cars, the W164 ML and the W251 R-Class at the top. The V8 is governed by the 10.4 to 16.4 hour cover-removal spread instead. Summed, Mercedes' warranty operations for the V6 come to roughly 25 to 35 hours before overlap is deducted. An independent shop working without that operation structure lands lower, which is where 18 to 28 hours comes from.

Adding the timing chain, guide and tensioning rails puts another $400 to $900 of parts in and adds little labor once the engine is apart. If the camshaft journals are already scored, this stops being a timing job and becomes an engine decision. Dealer estimates usually run higher, mostly on labor rate. Compare written estimates line by line.

Plan on the car being down for days, not an afternoon. Two oil changes with a road test between them are part of the repair, and the kit is ordered against your VIN, so ask your shop for its own timeline and parts lead time.

Is it worth fixing on a 2006 E350 or ML350?

Most of these cars are seventeen to twenty-one years old, and on a lot of them the repair estimate is a real fraction of what the car is worth. That is a fair question, and the answer is not always yes.

Look up your own car's private-party value before you decide; we are not going to invent a number for your VIN. Our rule of thumb: if the repair is more than about half of what the car is worth in running order, and other deferred work is stacked behind it, we will tell you to sell it and put that in writing.

#Is it safe to drive with P0016 and P0017?

For weeks or months after the light comes on, the car drives normally. The cam adjusters are quietly compensating, and nothing about the way it drives suggests urgency. That is what makes this failure expensive. Often an emissions inspection is what finally forces the issue.

Meanwhile the worn teeth keep shedding metal into the oil, and that debris goes through the pump, the galleries, the cam adjusters and the bearing surfaces. Contaminated adjusters can throw their own faults, which is how a shop ends up chasing solenoid codes that are really a symptom of something else.

Further along, the tensioner runs out of travel and the chain rattles, worst on a cold start. Chain slap then works on the plastic guide rails, and pieces of broken rail can end up in the oil pan. The end state is scored camshaft bearing journals. The valve covers on these engines double as the camshaft upper bearing carriers, so journal damage means heads and covers, or a used or remanufactured engine, typically estimated at $8,000 to $16,000 installed. On a 2006 E350 that can be more than the car is worth.

Owners have also reported chains jumping far enough for valves to hit pistons. That is the worst case, not the usual progression, but it becomes possible once the chain rattles. For a general take on which warning lights can wait, see BMW Check Engine Light: Flashing vs Steady, Cost to Fix.

#P0016 and P0017: reading the codes correctly

A generic reader hands you P0016 and P0017. A tool that speaks Mercedes gives you the factory codes and the camshaft adaptation data behind them, which is what separates a gear problem from a solenoid problem. The bulletin covers three scenarios, and only one is expensive.

The defining characteristic of the gear scenario is in the bulletin's own words: "When the fault memory is erased and the engine is restarted, the fault codes reoccur immediately." That is not the same as the dash light going out by itself. The MIL can extinguish after a few clean drive cycles while the codes stay stored in the module, which is why an owner can tell you the light went away for a week. What matters is whether the codes come straight back after a clear and restart. Codes that genuinely stay gone for days are telling you something else.

The solenoid scenarios carry much higher serial cutoffs: up to 759427 on the M272 and 193592 on the M273 for the fault-code version, and 895140 and 236360 for the oil-leak version. Far more cars are in range for the cheap problems than for the expensive one.

One caution, because it trips up good shops. Some published guides list the solenoid codes as the balance shaft codes, and some list P0008, P0009 or P0019 as indicators. Mercedes' bulletin names only 1200 and 1208 for the gear. The same solenoid-versus-mechanical fork shows up on BMW VANOS Solenoid Failure: 2A82/2A87 Symptoms, Cost, Fix.

#How it gets diagnosed without guessing

1. 01
   Screen by engine number firstBefore anything is touched, compare the engine serial to the cutoff. Above 468993 on an M272 or 088611 on an M273, this is almost certainly not your problem, and the work should turn to solenoids, sensors, oil condition or chain stretch.
2. 02
   Pull codes with a Mercedes-capable toolFactory XENTRY or DAS, or a capable aftermarket platform, gets you the native 1200 and 1208 codes plus live camshaft adaptation values. A $30 reader gives you P0016 and P0017 and nothing else useful.
3. 03
   Triage which of the three scenarios you are inGear codes that return instantly on restart, solenoid codes, or a solenoid leaking oil with no codes. Confirm oil level, specification and condition here too, then actuate the cam adjusters and watch the position data respond. Degraded oil produces adjuster faults that mimic this.
4. 04
   Run the 305-degree basic timing checkThe factory method, and the definitive test short of teardown. With all four camshaft Hall sensors out, the crank is turned in the direction of rotation to the 305 degree mark against the front cover pointer and the impulse wheel markings are read through the sensor openings. Healthy, they sit centered; on this failure the left bank centers and the right bank sits off. It is a shop procedure: turning the engine the wrong way or dropping debris into a sensor opening creates a new problem.
5. 05
   Look at the gear before anyone sells the jobThe bulletin's first repair step is a visual inspection of the tooth profile with the timing case cover off, which on the V6 means the engine is already out. Short of that, some shops pull the right cylinder head cover and borescope down at the sprocket. It is not a factory-documented method and does not always give a clean view, but paired with the 305-degree result it is usually enough to commit.

The 305-degree check confirms or kills the diagnosis before anybody quotes an engine-out job, and comparing bank to bank is what makes it readable. If a shop wants to sell you a balance shaft on code evidence alone, ask whether they ran it.

One more check before you spend anything. A Mercedes dealer can run a VMI, a Vehicle Master Inquiry, on your VIN, which shows warranty, goodwill and settlement repair history. Dealers generally run it for the registered owner, so on a car you are shopping, ask the seller to request it.

#What the repair actually involves

This is a timing drive teardown with a mandatory decontamination protocol attached. The bulletin lays out the sequence, and the order matters.

1. Inspect the gear visually with the timing case cover removed.
2. Only if the tooth profile is damaged, replace the balance shaft on an M272 or the guide/idler gear on an M273. The cylinder heads stay on. On the M272 the counterweight goes with the shaft, and both are specific to the engine designation, so parts are ordered against the VIN.
3. Replace the engine oil pump.
4. Replace the chain tensioner, installed last, after the valve covers are bolted on.
5. Change oil and filter with inexpensive oil to MB 229.1 or 229.3.
6. Road test under load for about 15 miles to circulate the flush oil. That is a shop step, not something to improvise on public roads.
7. Change oil and filter again, this time with MB 229.5 oil.
8. Replace all four camshaft adjustment solenoids.

Steps three, five, six and seven exist to flush out the metal the worn gear shed into the engine. Skip them and that metal stays in circulation, where it can go on to score the camshaft journals. Ask any shop whether their estimate includes the full sequence. The bulletin is equally blunt about cleanliness: no abrasives on sealing surfaces and no excess sealant, because either one can do permanent engine damage on its own.

Does the engine have to come out?

This point gets misreported a lot online, and Mercedes' own labor operations settle it. For the M272, the warranty operations include engine removal, and both the balance shaft operation and the timing chain cover operation are written as performed with engine 272 removed. There is a fastener behind the flywheel. The engine comes out.

For the M273 the operation is timing chain cover removal in the vehicle at 10.4 to 16.4 hours, with no engine R&R operation listed at all, and the idler sprocket swap itself allowed at 0.1 hours. On the V8 the gear is trivial once you are in. The whole cost is getting the cover off.

Doing the V8 in the car is not easy. Depending on chassis it can mean pulling the cam gears, both oil pans and the exhaust manifold, then raising the engine to clear the oil pump. Some shops pull the engine anyway and work on a stand. Which way it goes gets decided per car and shows up in the written estimate.

#What the gear does and why it wears out

The M272 is a 90-degree V6 derived from the M112. A 90-degree V6 is not inherently balanced, so Mercedes fitted a counter-rotating balance shaft in the vee of the block. Its sprocket sits in the timing chain path, so it does two jobs: spin the shaft, and route the chain.

The M273 V8 has a cross-plane crank and needs no balancing, so Mercedes put a plain guide gear in the same spot, which the bulletin calls the "guide (idler) gear for the timing chain on engine M273." The job is different, but the location and the failure are the same.

The defect is stated plainly: "The material for the balance shaft sprocket and the timing chain guide wheel (idler) was modified on engines past the serial numbers listed above." That is the extent of what Mercedes admitted. The material changed, not the design, and the early tooth flanks were too soft for the load the chain puts on them.

1. 01
   The chain machines the teeth awayA chain running over a gear softer than it should be removes material from the tooth flanks, until the teeth go from a correct profile to thin, hooked and pointed. The bulletin includes photographs of worn sprockets beside a new one, because the visual difference is the diagnosis.
2. 02
   The tensioner hides itAs material disappears the chain rides lower on that gear and the chain path length changes. The hydraulic tensioner takes up the slack, which is why there is no noise and no driveability complaint early on.
3. 03
   Bank 1 cam timing drifts retardedRedistributing that slack leaves the camshafts on the right bank, cylinders 1 through 3, retarded relative to the crank. Nothing jumped a tooth. Both cams move together because the chain drives the intake cam and the intake cam drives the exhaust cam through a gear pair on the head, which is why P0016 and P0017 arrive as a pair.
4. 04
   The adjusters run out of authorityThe cam adjusters compensate until the error exceeds what they can correct, and then the module sets the correlation faults and the MIL comes on. Everything removed from those teeth is by then in the oil, which is the reason the repair mandates a new oil pump and two oil changes.

#Is there a recall? The class action and whether yours was fixed

There was never a recall. There was a class action: Seifi v. Mercedes-Benz USA, LLC, case 3:12-cv-05493 in the Northern District of California, filed in 2012. The court preliminarily approved the settlement on April 8, 2015, and Judge Thelton E. Henderson granted final approval on August 17, 2015. The class was nationwide, every US purchaser or lessee of an in-range M272 or M273 car, not just California buyers.

It extended coverage on those vehicles from 4 years / 50,000 miles out to 10 years / 125,000 miles, with reimbursement tiered by age and mileage at the time of repair: full inside 4 years / 50,000 miles, 70 percent to 8 years / 80,000 miles, 37.5 percent to 10 years / 125,000 miles, and nothing past that. The claim deadlines passed years ago. If you think a past repair should have been covered, that is a question for the settlement administrator or a consumer attorney, not a repair shop.

That is why the VMI lookup matters. If it shows the gear was replaced, the car has the revised-material part. Repeat failures of the updated gear are not a known pattern, but Mercedes has never published data either way, so treat that as trade experience, not a guarantee.

#Buying a 2005-2007 Mercedes with an M272 or M273

You cannot prevent this. It is a manufacturing defect in a batch of parts, and oil, driving style and service intervals do not change the hardness of a gear that left the factory too soft. What you control is whether you find it early and whether you buy one blind.

• Check the engine number before you buy. On any 2005-2007 M272 or M273 car, the serial decides whether you are buying a known liability.
• If you own one in range, a 305-degree timing check will show drift before a light comes on. It is optional, and it is diagnostic time you pay for.
• Take the first check engine light seriously. On an in-range engine, codes that return immediately after a clear are the clearest warning you get.
• Do not let a shop throw sensors and solenoids at it before the mechanical timing check.
• Stop driving it once there is an audible rattle. At that point the chain and guides wear with every mile.
• Request a VMI. If it shows the gear was already replaced, this specific problem has been dealt with.
• Insist on the full bulletin sequence: new oil pump, single-use tensioner last, new impulse wheels, both oil changes with the road test between them.

If the engine number is in range and there is no record of the repair, price the car as though the repair is owed. It may never need it, but nobody can promise that it will not. The W204 C-Class, the GLK and M276-powered cars from 2011 on are not part of this bulletin.

One caveat on the range. There are owner reports of the same symptoms and the same repair on engines above the cutoff, and Mercedes never extended the range. Treat those as outliers, and remember a stretched chain sets identical codes. The same wear-versus-tensioner logic runs through BMW N20/N26 Timing Chain Failure: Symptoms, Cost, Real Fix.

#Doing it yourself: tools, parts and specs

Honest verdict first. On the M272 this is not a driveway job: the factory procedure has the engine out, the tensioner is single use, and the impulse wheels and adjuster holding pins are easy to get wrong in a way that costs you the engine. On the M273 the gear itself is a 0.1-hour operation, but it sits behind the longest single operation in the job. If you are still reading, here is what the paperwork says.

Bulletin

Mercedes-Benz DTB S-B-03.30/08, revision 08i dated April 23, 2009. Supersedes 08h of October 24, 2008; initial issue August 23, 2007.

Serial cutoffs, gear

M272 to 468993, M273 to 088611. Not applicable to model 164.156, 204 or 216.386.

Serial cutoffs, solenoids

Fault codes: M272 to 759427, M273 to 193592. Oil leak: M272 to 895140, M273 to 236360.

Balance shaft kit, M272 2.5L (272.920)

A272 030 00 13, now supplied as 2720300413

Balance shaft kit, M272 3.0L (272.94X)

A272 030 01 13, now supplied as 2720300513

Balance shaft kit, M272 3.5L (272.96X / 272.97X)

A272 030 02 13, now supplied as 2720300613

Guide / idler gear kit, M273

A272 030 03 13, now supplied as 2720300713

Camshaft adjustment solenoid

A272 051 01 77, four required

Chain tensioner

A272 050 08 11, single use. The bulletin footnotes it: confirm the number for your model in EPC.

Before you order

The bulletin says to refer to EPC and order against the VIN. Balance shaft and counterweight are specific to engine designation, and these numbers have superseded at least once.

Special tool

W001 589 81 09 00, to remove and install the timing case cover

WIS procedures

Timing case cover AR01.40-P-8000*, balance shaft and idler gear AR03.20-P-1000*, oil pump AR18.10-P-6020*, solenoids AR05.20-P-7295*. The asterisk is a model suffix, e.g. AR03.20-P-1000VA on model 171.

Labor operations

M272: 01-8005 cover with engine removed, 01-2800 engine R&R, 03-4731 balance shaft, 18-6022 oil pump, 05-7290 four solenoids. M273: 01-8000 cover in the vehicle, 05-8052 idler sprocket at 0.1 hours.

Torque

We do not publish torque values here. They are model and build specific and several fasteners are single use. Use the current WIS figures for your engine designation.

The bulletin lists the M272 kits as shaft, counterweights and chain tensioner, and the M273 kit as guide sprocket with bearing, tensioner, oil pump, solenoids and seals. Current listings for the 3.5L kit also show the adjuster magnets, four impulse sender wheels, filter kits and the crankshaft sealing flange, so check the contents for your engine designation rather than assuming.

While the front of the engine is open, the timing chain, guide and tensioning rails, water pump, thermostat, crankshaft front seal and valve cover gaskets all overlap on labor. None are required by the bulletin, so decide on mileage and condition. On the M272 the intake manifold swirl flap assembly is a separate common failure, and doing it now avoids paying that labor twice.

We do this work at the shop in Melissa. Every visit starts with a free 49-point inspection and a written estimate before anything is touched, and we photograph what we find, which here means your gear teeth next to the bulletin's reference photo. Repairs carry a 24-month/24,000-mile warranty on parts and labor, whichever comes first, on the work we perform. It does not cover damage that was already in the engine. Terms are on our terms page.