After many hours of internet research over the past couple of months, I have been unable to find an online Mercedes engine number database, through which one could cross-reference engine serial numbers against engine specifications, year of manufacture and vehicle compatibility data.

I have been searching local car engine importers' stocks here in Africa, to locate a M273 E55 (5.5 liter V8) engine for my 2009 C209 CLK550, whose original factory motor, bearing serial number 273 967 30 281 116, is now destined to sleep with the fishes, after duly serving as a source for cannibalized engine ancillary parts, when I eventually locate and transplant in a replacement motor.

Looking at this cut-and-paste I have borrowed from Wikipedia below, the M273 was manufactured in two versions, namely the 4.663 liter V8 that was only installed in three 2007 Mercedes models, in contrast with the M273 E55 5.461 liter V8, that was a power-plant option in about twice as many Mercedes models that were marketed between 2006 and 2009.

Mercedes M273 Engine Wikipedia Extract.E47

The E47 is a 4.7 L (4663 cc) version. Bore is 92.9 mm and stroke is 86 mm. Output is 335 hp (250 kW) at 6000 rpm with 339 ft·lbf (460 N·m) of torque at 2700-5000 rpm.


Applications:
· 2007– GL450
· 2007– S450·
.2007– ML450

The E55 is a 5.5 L (5461 cc) version. Bore is increased to 98 mm and stroke is up to 90.5 mm. Output is 382 hp (285 kW) at 6000 rpm with 391 ft·lbf (530 N·m) of torque at 2800-4800 rpm.

Applications:

· 2006– E500/E550
· 2006– CL500/CL550
· 2006– CLS500/CLS550
· 2006– GL500/GL550
· 2008- ML500/ML550
· 2006–2009 S500/S550
· 2006–2009 CLK500/CLK550
*Note: 500 or 550 model naming varies depending on geographical market.

Now, since all M273 engines bearing serial numbers whose last 6 digits range up to 088 611, are susceptible to timing chain idler sprocket failure, while all M273 engines bearing serial numbers whose last 6 digits range up to 236 360 could develop leaks around the camshaft adjustment solenoids, I obviously hoped to find a used M273 whose serial number’s last 6 digits would be above 236,360.

Cutting to the chase, I would like to find out if it is possible to refer to the engine number so as to distinguish a M273 E55 engine made after late 2008, from an earlier M273 E47 engine that was an option in just three 2007 Mercedes models. I ask this question because Wikipedia does not make it clear as to whether the same serial number sequence was used on ALL M273 engines, or whether the M273 E55 and M273 E47 do NOT bear serial numbers in a common numerical sequence.

If I am correct in presuming that ALL M273 engines bear the same serial number sequence regardless of whether they are the E47 and E55 variants, then of course my search for a M273 motor will boil down to simply checking the last 6 digits of the engine serial number, to be sure that the number is greater than 236,360. I sure would be grateful to read any assurances that can be offered by the experts here, that this simple serial number search will identify the right engine for me.

Finally, the first six characters of the serial number stamped in “Braille” on my car’s original engine, are 273 967 30 - - -. Thus far, my used engine search has yielded M273 engines whose serial numbers begin with 273 960 30 - - - and 273 963 30 - - -273 968 30- - - and 273 969 30 - - - . For now I have chosen to hold off on buying any of those engines, on account of my determination to find an engine whose serial number starts with 273 967 30 - - -, so as to ensure a perfect engine-mount match for the transplant motor in my 2009 CLK550.

My uncertainty with the first 6 digits of the M273 engine serial number centers around whether I can go ahead and purchase any M273 engine bearing a serial number whose last 6 digits are in the “safe range ” above 236 360, regardless of whether the FIRST six digits of the serial number are not a perfect match with 273 967, but rather a close match such as 273 960 or 273 963, as I found on the engines on sale here thus far. I don't want to be faced with calling in a welder to relocate engine mount bracket positions on the car's frame, unless the right engine cannot be found here after an even more exhaustive search.

Despite my futile online search thus far, I am convinced that there has got to be a Mercedes database somewhere online, where it is possible to conduct engine serial number searches, in the same way as is available with numerous websites that offer VIN check facilities.

Any thoughts that can be shared on my engine serial number questions would be very helpful indeed, as I push forward with my search for the elusive year 2009 M273 E55 engine that will finally revive my currently mothballed CLK550 project car.

 

I would not worry about an engine beyond serial number 088611. If the camshaft solenoids fail or leak, you can just replace them. Here in the USA, all four are under $100 total.

 

Much thanks Rodney. I was already thinking along the lines of re-using the solenoids off the damaged engine I have here, if the only engine I can find to buy falls within the leaky solenoid range, just as a stop-gap measure to test run the motor before the sellers short warranty period expires, and until new solenoids arrive in the post.

Regarding the FIRST six characters of the engine serial number, and my inability thus far to locate an exact match to the 273 967 engine model that this car requires, I will probably go with the mechanic's idea of dismantling the old non-running engine, and taking the crank-case along to match up the engine mounts on my car's crank-case, with those of any 273 motor that I intend to buy, provided that the serial numbers's last six digits are greater than 088 611, to stay clear of the idler sprocket defect.

Thus far, we were shown M273 engines whose serial numbers start with 273 960, with 273 963, as well as 273 968 and 273 969, but NONE thus far which perfectly matches the first 6 digits of my CLK550's engine, namely 273 967, so a physical comparison of the crank cases, at the engine sellers' shop may be the way to go, in the absence of an online Mercedes engine serial number decoding website.

 

These engines all have identical blocks and heads. The differences are in the attachment parts like the bell housing , oil pan and belt-driven accessories. If you can't find an exact match, then you can just swap the different parts. Note that the last eight digits is the block serial number, and even with the different variations, the serial numbers run sequentially, so there is only one M273 engine with the last eight digits of "30 362335" and it's an M273.965 (R230 SL550 engine, the one in my car).

 

This clarification does make my search much easier, Rodney. My hopeful speculation is now confirmed, that all M273 V8 engines, regardless of specifics unique to each family of Mercedes vehicle for which they were intended, do bear the same numerical sequence in the last 6 digits. This fact does simplify my engine search for sure. It is also a relief to learn that all ancillary engine parts such as the oil sump and power steering pump, can all be transplanted from the damaged engine to the replacement motor with ease. The one facet of the engine that remains unknown to me is whether or not the engine mounts on all M273 engines are identical, regardless of the vehicle for which they were originally designated.

I just got done transplanting a 5-liter M119 engine from a 1991 year R129 , into my 1994 year E420, and during that swap, it became apparent that the engine-mount positions on the car's chassis frame had to be relocated with some tricky welding, before the R129's M119 engine could be shoe-horned into the E420's engine bay. My DIY E500 does run just fine after this swap, but that experience alerted me to the fact that even within the various Mercedes engine designs, it is possible for the engine crank cases to have been manufactured with more than one engine mount configuration.

Once again sir I must convey my gratitude for these design specifications that you have been kind enough to share here. My M273 engine search just got a whole lot easier, thanks to this information. The mechanics are heading over today, and they will dismantle the damaged M273 motor, so I can store all the ancillaries in readiness for when the replacement M273 is located. The stripped-down crank case will be a lot easier to lug around the city for use in matching up to confirm engine mount compatibility with that replacement M273, just in case the engine mounts do vary from one car to another, as we discovered was the case with the M119 V8 motor.

 

Hi, i know this is an old post, was just wondering what eventually came of it.
However the last 3 digits of the first six in the engine number differentiates the engines variants;
273.962.....E550 4MATIC
273.960.....E550 RWD
273.968.....S550 4MATIC
273.961.....S550 RWD
273.963.....GL550 4MATIC
273.923.....GL450 4MATIC

 

Hello Ekene and thanks for this very informative listing of M273 engine variants. I have cut and pasted this serial number classification list you have kindly provided, for addition to my database of all things Mercedes. Just so happens that I am currently toying with the idea of buying a 2009 Mercedes E550 (W211), whose air suspension I would immediately convert to standard shocks and springs that are sold as a kit by Strutmasters and Suncore, online. Ever on the lookout for cheapskate car deals, I may wind up with an E550 that either has no engine, or needs one replaced, meaning of course that I may well in the near future need to once again delve into the list of motors that would work with my intended purchase of a W211 E550,

My original questions about the M273 engine were in relation to my 2009 CLK550, whose water damaged engine I replaced with a M273 motor that came out of a 2008 Mercedes S550, and which, knock on wood, is still running smooth and strong.

 

To answer a few questions...

The last 8 digits is the serial number and it is totally sequential through the entire M273 series, regardless of displacement or sub-code.

The three digits after the "273" do indicate various different applications. While there are no differences among these with the same displacement, there are differences in things like engine mount locations and accessory (alternator, AC compressor, etc.) bolt locations.

 

Clearly the 4th, 5th and 6th digits of the engine serial number are the ones to watch for anyone contemplating a M273 engine transplant. Also, the last three digits of the serial number must run sequentially across all M273 engine models, to make for easier tracking of manufacture date.

 

Hi everyone and those that might reference in future.
Amoungst my Merc's I have 2x 2006 NZ new, special order CLK500's, both with M273 and 7speed.
In both cases Mercedes NZ was able to confirm from there database that both of my engines had comprehensive work done under warranty replacing the sprocket, timing chain etc.
Both are brilliant cars, with differing options, one has now done over 100,000 miles and is my favourite daily driver (in black) even more so than even my CLK63.
My thoughts are that the early versions are not a right off, far from it, especially if you can identify if they were addressed under warranty early, and have a history.