Looking to buy a M272, wondering about the balance shaft gears
 

I'm looking at a 2006 C230 with the M272 engine with 170,000 miles on it and I've heard this engine has a problem with the balance shaft gears. Somewhere it was mentioned it would fail at about 70,000 miles, could I assume that it's ok now? I'm thinking either it was already fixed or it's not a problem with this engine, that is if it hasn't failed by now it's not going to.

I just took it for a test drive and the engine seems a little rough for a six cylinder, but i'm used to my smooth as silk in line six M103. It almost seems like the balance shaft was removed. Is this normal for this engine?

I once looked at buying an otherwise very nice car from dealer. It had the M272. Dealer told me that only a small percentage failed (he was trying to SELL car). I found out that he was partly right, but the problem was that MB had no record of which engines received the bad parts. I decided to walk away. And the engine should not run rough. Recommend you find a better car to buy.

Have your local MB dealer run a VMI for you. This will tell you if the repair has been done or not. The balance shaft issue has been covered in a Tech Bulletin which lists the engine number range affected........

It's true that only a certain range of engines might have the problem. But the range of possibly affected cars is quite wide. This is a useful link and covers almost everything you will need to know:

Mercedes Benz balance shaft engine issues. How to check by VIN. M272/273 - MB Medic

If its running rough it could have a failed intake runner flap, or bad engine mounts.
It should be smooth. Just did the repair on mine -- You can see the broken plastic in the center.

http://w124-zone.com/downloads/photo...manifold/1.jpg

http://w124-zone.com/downloads/photo...lerflap/10.jpg

http://w124-zone.com/downloads/photo...lerflap/11.jpg

At 170k I would replace the entire manifold due to the plastic inside if that is the problem -- so thats $550 in parts at best (wont always show CEL! needs to be scanned by MB or good scanner).

Balance shaft is a lot more and requires engine out, so priority #1 would be verify if its been done. If its within the engine range and has not been done, I would walk.

The car has just under 170,000 miles on it. Could I assume that if it hasn't failed by now it's not going to, or already been fixed. I'm guessing the fix was good?

The VIN is WDBRF52H36A907204 if anybody can do anything with it. Soon I'm going to pay to get a CarFax on it, unless anybody has a better place.

While the engine seems to run rough it definatly has the power.

To echo what others have already said, if you can't definitively prove that the balance shafts have been redone (BY A MERCEDES DEALER), simply WALK AWAY. Another one will come up that fits the bill and has had the repair done.

The balance shaft is there for make the engine SMOOTH. If it's rough, there's a problem. Could be one of many things, including fuel, ignition, or other mechanical issues. If you're dead-set on the car, take it to a reputable indy and have them check it over for faults (if it's running rough it certainly has some sort of fault).

I wouldn't waste too much money on Carfax, or if you do, take their report with a gain of salt. It certainly won't show if any recalls or dealer service have been performed. One of my friends totaled their car and elected to have it repaired (salvage/rebuilt title). When they went to trade it in a couple years later, they ran a CarFax and it showed it had a clear title with no accident history. Not exactly accurate...

If the balance shaft gears strip, the effect isnt just a rough engine, its a very noisy engine accompanied with cam position (TDC) failures showing up as check engine lamp codes as the cam timing goes out of sync because the timing chain is flopping about.

If its just a rough effect while driving it mostly bad motor mounts or that broken piece on the intake manifold as shown by p2scho. The 112 engines also feel very rough when the motor mounts collapse - specially pronounced if the engine is dead cold and in D. The roughness also can be due to a bad torque converter but thats when your trans fluid mixes with antifreeze.

The 272 balance shaft repair is not a very user freindly job due to the design of the engine. So dont buy one as a fixer upper.

Jim:
Pull the stored codes. If you show P0016 and P0017 you have the problem. Mine is a 2006 C230 Sport with 108K. I got the problem. You need to pulll the engine to replace the balance shaft. I fortunetly can do the repair myself. The dealer wants about 5K. For a 5K car this makes no financial sense. So if you can't do the work yourself, its scrap, or part it out on ebay. These M272 engines are problematic.
The intake linkage is also another common failure. In my opinion these engines are over complicated junk. Four overhead cams, mulitvalves per cylinder, variable valve timing, variable intake runners. For what? A wopping 200hp! I have a 1972 chevy pick-up with a straight six that makes 200hp. The Emperor is naked!
Late model Merc's aren't what they used to be. The Emperor is naked!

My M103 makes what 160HP out of 6-cylinders and gets me 22mpg. My E350 puts out 270HP, has permanent AWD and all the additional features and gives me 24mpg.

So ~120HP +2mpg along with a fraction of the emissions...I wouldn't say its "junk".

As if the M272 didn't have enough of a bad repuation for :

(a) Balance shaft sprocket failure and associated timing chain failure.
(b) Cam plug oil leak

It seems that there was an OEM source who provided Big End bearings which were slightly too undersized. Latest engines run very hot for reduced emission control. The hot engine feature causes the faulty big end bearings to expand a little. Engines with these bearings produce a sort of Donk Donk noise for a few seconds after cold start up.
Repair is engine out, sump off and replace with better tolerance units.
This is a pot luck problem. You will be unlucky if you have an engine with this issue.

When I was shopping for a w211 wagon I tried to avoid the m272 like the plague because of these very issues. And from what I saw the early m112 and m113 powered w211s now sell for more than the later m272/273. The cat is out of the bag and people know to avoid these cars. MB fixed the balance shaft issue half way through the 07 model year but all m272s before that are suspect.

Beyond the balance shaft issue the 272/273 are too complicated for their own good. The intake manifold is just one example.

That's why I got my 272 outside of the balance shaft range. If you stick with 2008-2009, the only real expensive engine related issue is the runner flaps. Did mine earlier this year and I expect the engine to be very reliable and have little issues for a while now.

But yes nobody wants any V6 MB from 2006-2007. The ML's sell for absolutely nothing and I feel bad for suckers who fall into that money pit trap.

M272
 

Bought my ML350 new in 2006. Replaced cam plugs at 60K, Replaced every coil at various miles, Replaced intake at 80K, replaced The Balance Shaft at 100K. And that was just the engine., The other big job was sending out the 722.9 trans electronic conductor plate to have the solder re-flowed because of the bad speed sensor problem.
It is a good thing I Love working on cars!:D
......And I will never buy a new car again! I have no problems with all the used cars I have purchased . Just minor stuff nothing like the Ml350 M272.