M103 vs. M104
 

What was the first year MB used the M104 engine in the W124 Chassis? Was it '93?

What was the last year of the W124 chassis?

How does it compare to the M103 in power, reliability and longevity?

Any problems inherent in the early model years of the M104 (not just the engine, but the car in general)?

What octane gas is recommended for the M104?

I'm trying to decide between an 92 300E and a 93 to 95 model.

Thanks

Some answers to your questions ...
 

Last year for W124's in USA was 1995.

M104 requires permium unleaded - I'd say 92 octane or higher.

In 1990, 300CE was first W124 to have the M104 engine.

First year of the 104 was 92 in the 2.8 300E I believe (? not sure)
Last year of the W124 was 95.
Personally I would get the 103 if its in good condition and near 100k :)
Mainly, because in the later cars, ASR is a pain when it goes bad and the engine harness problem can cause serious issues. But if these problems have been dealt with and certified in the one you are considering then the later 94-95 W124 is almost a perfect W124.

First year of the 104 in the 124 sedan was the 2.8 and 3.2 of 1993 but as mentioned it was in the 1990 coupe as a 3.0. Both 103 and 104 have their strong points and weak points - there's no clear answer on which is better. The 104 has a little more power and actually gets better gas mileage with HFM in 93. For a DIYer it's tough to beat a 103 motor - simple and lots of room.

One of the thread experts, MBdoc says the 92 300e is one of the best Mercedes ever built. He said he'd own one.

That was a pretty strong endorsement.

deanyel is correct.

1993 300E's badged "300E" have the same 3.2 liter M104 engine (M104.992) found in 1994-1995 E320's. MB (in the U.S.) for some reason didn't change the badge until 1994, but in the rest of the world, 1993 300E's were badged as 320E's.

This 3.2 liter engine was also used in W210 chassis 1996-1997 E320's as well as 1993-1999 S320's (W140 chassis).

1993 models badged as 300E 2.8 have the same 2.8 liter M104 found in 1994-1997 C280's.

1990-1992 300CE's have a different M104 engien (M104.990). This 3.0 liter-24 valve M104 engine is an early version of the 24-valve DOHC 3.2 liter M104 engine used from 1993-on. The 3.0 liter version still used the CIS-E fuel injection system as 1986-1992 3.0 liter M103 engines, using a distributor with one coil wire and 6 spark plug wires. This is basically a mechanical injection system with electronic control.

The 3.2 liter M104 engine uses a different ignition system - HFM (hot-film mass air flow sensor), fully electronic with integrated electronic ignition and sequential fuel injection. This system combines fuel injection and ignition control in one module. HFM-SFI systems use coils that are mounted directly on the spark plugs, replacing the distributor at the front of the engine. Each coil pack provides spark to two spark plugs at the same time, one connected directly to one plug, and the other with a short high tension lead to the next spark plug. So there are 3 coil wires and 3 high tension lead wires.

HFM fuel injection systems are designed so that idle speed can't be adjusted. Idle speed is completely controlled electronically. This HFM injection system also has adaptive technology that compensates for conditions such as engine wear and unmeasured intake air and is designed to maintain driveability as the engine ages.

HFM-SFI can retard engine knocking to just the knocking cylinders, unlike EZL technology, which retards spark timing across the entire engine. This keeps the ignition timing point as advanced as possible for maximum power output.

The 3.2 liter M104 engines also have variable valve timing on the intake cam, making the torque curve broad and flat, developing HP at a much lower rpm. This makes the power much more useable and noticeable.

The problem with the M104 engine, in my opinion, is that they are more expensive to run. Why?

Early M104 engines had head gasket problems. Also, all 1993-1995 Mercedes have bad engine wiring harnesses. Last, M104 engines have an electronic throttle actuator which is notorious for failing. All three items are expensive to fix.

1992 300E's don't have the dreaded engine wiring harness problem, and also don't have a throttle actuator. Instead, they hava an idle control valve, which are not problematic.

Thanks guys, great information. It's really helping me to narrow down what I want.

Gary

I had a 93 briefly...fast car, noticeably faster off the line than my 420SEL (W126). I got rid of it because the interior seemed so small, and the black interior accentuated the tight feeling.

Before I bought my E430, I owned a 1993 300E (3.2).

In fact, I decided to correct the badging error and re-engineered the badge to "E320".

It was a great car, but in my ownership I spent $1,800 on a new headgasket with new valve guides and seals, $1,500 in a new throttle actuator, along with about $2,000 in other various repairs.

both deliver...
 

Hello All!

Suginami just provided an excellent breakdown on the 90's W124 engine variations. Besides significant technicalities under the hood there are also modifications and changes in body design which make the 94 and 95 models look noticable different.
Maybe it is a preference, but I think the last of the W124 in 94 & 95 appeare more like 'fully matured' in design.

I have to admit, if I would have known all the details in electronic control systems of the late models I probably would have chosen an earlier model.

Well, I went by the condition of the vehicle. As those models all together are getting older, I think it is paramount to find one that really is in the best possible condition with low documented miles.

As far as driving experience goes, it feels like the DOHC 320 acts with more ease then the SOHC 300. Yet, they both deliver nice 6 cylinder power.

It's pretty simple - the later W124s with the M104 have more power in the lower RPMs which is very noticeable in everyday in-town driving. But that added power comes with a price in added complexity, somewhat reduced reliability, and somewhat higher cost of maintenance.

The earlier W124s with the M103 have less low-end power, though they are not slow by any means, especially on the highway. In exchange for a little less low-end power, you get simplicity and ease of repair which tends to equate to somewhat greater reliability and lower cost of maintenance.

Take your pick. In 2004 I bought a 91 with 120K on the odometer and it is easily the best car I have ever owned. Though it now sits in the garage as my fair weather third car, I put 30K miles on it using it as a daily commuter the first year I bought it. In that 30K I spent less than $1,000 in total repairs and maintenance which included oil changes with dino every 5K, tune-up, a set of Kumho tires, tie rod end and alignment, a water pump, tranny throttle body rebuild, tranny fluid change, and alternator voltage regulator. Of course I provided the free labor, which is key if you want to own one of these. Otherwise, doing the math I would have easily spent somewhere around $4,000 to $5,000.