OK so now I'm researching the M104 engines. I'm looking at getting a W124 coupe. I prefer the exterior styling of the 94-95, but ANY year can be easily updated with just a new hood and lights, so my concern now is the engine.

Both put out 217HP. But which one is better in terms of reliability and cost of ownership?

I'd like to hear which cars mechanics see in the shop more. I'll be buying this car (W124 coupe) in June of 2007 so I have a few months to research this model and find my "perfect" car.

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JR
1986 Gold 300E 4Dr automatic

Well the 94-95 have a wire harness problem that MB won't do a recall on the car for this problem. My son has a 94 E320 and looks are nice on this model witch i need a hood for this car since the antilock brakes didn't work and the air bag didn't deploy either other than that it a great car
love the dual over head cam's rev's a lot quicker than my 300sel and 300E
i will be posting pic's of the progress on his car's repair and paint job

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Keeping 'em Running
1990 300SEL
1994 E320
1989 E300

The wiring harness issue is actually 93 to 95 but the vast majority of them have already been replaced. The 93 to 95s have more torque and noticeable better performance as well as better gas mileage. The 90 to 92 might actually be less trouble overall but have one big problem that would rule them out for me - the ignition control modules are failing. Used ones are very scarce, and expensive, and new ones are unavailable from MB even at a ridiculously lucrative list price. This is taking cars off the road for months at a time. Try a search - there's been some threads on the subject. The later 3.2 cars may be a nuissance at times but at least they can be kept on the road.

I ended up buying a 91 300CE for my wife last Christmas and both she and I love the car. I bought a pre 92 car because I was told by a Mercedes salesperson that after 1992 Mercedes started to cut corners to compete with Lexus and other luxury vehicles produced by the Japanese. I believe he is right and it made a difference in my choice.

Antonino

las769 - Thanks for the heads up on the wiring harness. I'll definitely get one with the updated harness (or adjust the purchase price for a replacement)

deanyel - The ICM on the 90-92 is what's scaring me. I believe it's something like $3,000 to replace. But my question to the mechanics is whether or not this is a big problem or only limited to a small number of cars. Also, if this unit is replaced, is the replacement better than the original? (Will I still have to worry about it if it's been replaced?

antonino - I believe it was in 96 that Mercedes started cutting corners to compete with the Japanese models. The 93-95 models are almost the same as the 90-92 except it has HFM. Don't get me wrong, if I find a well kept 90-92 W124 coupe I'd buy it. Right now I'm just trying to do my research to avoid the headaches.


All models have problems with the head gasket, evaporator, radiator neck
90-92 have problems with the ICM ($3,000 fix)
93-95 have problems with the wiring harness ($600 fix DIY)

88-89 have the M103...so far this seems like a "SOLID" engine, but I'm not sure if I'd be able to find a well kept one. Downside with these engines are is lack of power and poorer gas mileage.

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JR
1986 Gold 300E 4Dr automatic

Don't immediately discount these vehicles due to the M103. Though less powerful and, depending on driving style, yes you can get poorer gas mileage, the tradeoff is simplicity and robustness, as well as readily available parts and knowledge.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

IMHO, the HFM-SFI version M104 is far superior to the early CIS-E/LH-SFI engines. At the time I bought my '94 E320, I had the chance to buy a couple of earlier cars as well. The better diagnostics and performance of the HFM system made it an easy decision.

ILUVMILS, you have in-depth technical knowledge that a lot of members here don't have. Having had to chase faults on both engines, I can say that the M103 is much more DIY-friendly. No special computers needed, and much less intricate. I don't think the M103s are any more problematic than the M104s. Of course this is all just my opinion.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

JR, the 94-95 104 engines are lower revving for a given speed and have more torque at a lower rpm than the 90-92 104 engines. Specifically, the 94-95 104 engines develop 217hp at 5,500rpm and 229ft-lb torque at 3,750rpm while the 90-92 104 engines develop 217hp at 6,400rpm and 195ft-lb torque at 4,600rpm. I own each and the 1995 E320 is quicker than the 1992 300CE, and is more refined due to the lower revving engine.

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Fred Hoelzle

The 88-89s have the old style leather which has a different feel and a different stitch pattern - which gives it a somewhat dated look. Of course the 95s are now 11 years old so that could be considered a dated look too. In my view the car should have 8 hole wheels which may set you back about $500 on the earlier cars. Life is simply too short to clean 15 hole wheels.

I agree with you regarding the need for special computers. Without SDS, diagnosing M104 issues would be tough. With SDS, it's very easy. The reason I prefer the M104 though, is the performance. The combination of adjustable camshaft timing and the resonance intake manifold, along with four-valve technology, make these things fun to drive.

We had a 103 in a 90 E and I now have the 104 in my TE. LOVE the 104 and with 124K it still has the original harness and head gasket,,,, knock on wood. [ I didn't really say that].

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

Just a note for more accuracy, the 1993 300E also got the HFM-SFI 3.2 liter M104 engine. It shares the same chassis code as 94-95 E320's --- 124.032.

MB didn't change the badging nomenclature until 1994, so in 1993 300E's with the 3.2 liter engine were badged as simply 300E.

1993 300E's with the 2.8 liter M104 engine were badged as 300E 2.8.

In the rest of the world there wasn't a badging error as they were badged 320E or 280E.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I took the time to write a nice piece on the difference of these engines.

I found it and will copy and paste it here:

1990-1992 300CE's have a different M104 engime (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.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

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Due to the low cam swipe angle of the 104, there is no side force on the valve stems as the valves are pushed directly. Which is a big technical improvement over the 103 cam/valve arrangment. 103 has the common fault of worn guides ... one hardly ever sees this in the better 104 design.
.. and DIS w/full electronic HFM/SFI is far superior.