One of the things that I don't like about the 104 is that I have seen several low mile 104s that had a very pronounced piston slap. Granted I have a little slap in my 103 cold but it has 260k of hard miles. When I see a 104 with less than 100kmi driven by a little old lady and it slaps a lot louder than mine, I have to wonder...

Considering it has the same bore/stroke/dimensions and is nearly identical beneath the head gasket, that would surprise me.

I'd be more likely to expect premature cylinder wear on a CIS car from the characteristic injector dribble that washes the oil from the cylinder walls when parked.

I'm not referring to early 104s, rather the later HFM ones with the larger bore and stroke (3.2L).

These drivetrains were made to be pushed HARD 24/7. They do NOT like 20 years of being driven by an old lady that has never revved above 3000rpm, even once. At least that's my theory, and I'm sticking to it. :D

Sorry to revive an old thread, but I just test drove an M104 (2.8) and an M103 (3.0) back to back, so I have some thoughts to share.
I drove the 103 first and it gave strong linear acceleration. It builds speed in a very even and proportional fashion. All very proper and Mercedes-like.
But then immediately driving the M104, the difference was staggering. It wasn't just the power difference, it was the whole characteristic of the delivery. The M104 is so eager to go. If you're not careful modulating the accelerator, it'll jump forward off the line without trying! But that's not even the best part. My favorite is the delicious growl it makes when it comes on the cam. I was immediately hooked. (I'm an Alfa guy, so I really appreciate cammy engines)
I can only imagine how the extra 400ccs of the 3.2 would feel!

I have both..... 104 hands down. Smoother, peppier, just as easy to work on... (or just as tough to work on: water pump)

I wonder has anyone had a head gasket made with a cut out for chain.Then it would be one peice,head and timing cover.
there a place that makes special gaskets,and they have a M104 done before. think its called Gaskets LLC. They make copper,and shim gaskets or layered

I have owned both very recently, and still drive the 300E from time to time when my mom is up visiting.

I think my m104 is a little out of whack right now (EGR pipe needs cleaning, needs a FPR) but honestly I prefer the m103 over the m104.

Power delivery is very smooth, while not as much. Makes a nice sound, easier to work on, seems to get slightly better economy (though like I said my m104 is a bit out of whack) and I think the low end is a little bit better torque wise.

Not that I dislike the 104 or anything, I think it too is a great engine, but I still really like the m103.

I average 28.5 out of my m104 and 24 mpg town.Though I drive for mileage,the 28.5 fiqure was 40% city,and 60% highway.Would love to take a trip,all interstate and see if she does better.

My 103 is a lot smoother and quieter than the 112 in my 99 e320. The 87 is certainly not faster, hands down the 210 is faster. But I find the quiet smooth power curve of the 103 to be quite comfortable. I love driving a 124 anyway, always did.

I've had both. I love the stone simplicity of the M103. But the rush of the M104 wins for me everytime. Not sure I could go back to an M103.

Getting 27.5mpg on my recent roadtrip doesn't hurt either. I don't know how oldsinner111 gets 29 in a W140 but i sure would like to know.

I drive the speed limits,and practise hyper miling.I plot my routes here in the mountains with short climbs,and lots of downhills.I've never had her on flat interstates yet.Right now with only one third throttle,I'm getting 25 mpg county,and town.However afraid to climb with TPS not workiing right.

It may be an urban legend, but I remember a story where in the 1980's the MB engineers were at odds with the MB execs. The engineers wanted to improve the performance of the engine, while the execs insisted that the engines were the best in the world. I am assuming that the engine in question is the M103.

So the engineers invited the execs to test drive a special car with a secret prototype engine. There was a lock on the hood.
After driving the prototype, all the execs agreed that the engine was a vast improvement over the existing one.
So at this point the engineers dramatically unlocked and opened the hood to reveal a BMW engine which they had transplanted into the MB chassis.
This was the impetus to develop the M104.

Can anyone verify this story? Is it true, or just an urban legend?

Probably easy to conclude the M104 is a better performer unless you owned/drove both engines from new.

The M103 when new actually performed very closely to the M104 when new.
Much of the M103 performance is attributed to a lower final drive ratio.

I always found the M103 provided a much smoother power delivery then the M104.

Difficult to compare when both are used as condition is the "wild card"....;)