Engine Comparison (M103 vs. M104)
 

I just bought what seems to be a nice 1990 300E for my wife. This will be the first Mercedes we have owned with what I understand to be the M103 designated engine. Previously, I have had two E320’s (1995 & 1997) that had the next generation six (M104?). I really liked both cars, especially the 95; however the engine in both cars leaked oil around the timing cover and head gasket.

Was this common to that engine? Will the M103 be prone to the same? How do the engines compare in other maintenance areas and in performance?

Simply put, the M103 and M104 share the same block, primary differences are the head and the injection setup.

Head gasket and oil leaks are common to both engines.

Unrelated but tied to the M104 is the crumbling wiring issue, and evaporator failure.

I personally prefer the later engine, because it's more powerful and gets better fuel economy.

A 1990 is a good choice, you get the cosmetic updates, and it predates the wiring harness and evaporator issues.

Jim

The 103 head gasket is a problem if the car overheats....otherwise it should be ok from leaks...

The timing cover gasket is another story.... it starts leaking in small drips...then it seems to get worse.... doesn't take too long to change... a couple of hours... the part is four dollars.

i like the 104 a bit better, too..... it's smoother and a bit more powerful. We have both.

104 is smoother, much more powerful, better self-diagnostics, and better fuel mileage.

The wiring and evaporator problems are shared by the later 103 and the 104.

I had a 90 300e 2.6L that had over 200K mi on it. Had to do valve stem seals becuase it kept fouling #3 plug. Car ran like a champ just have to watch the tranny in that car. They are prone to losing reverse. Those were some of the most reliable cars MB ever built. I now own a 95 C280 with a M104. Both cars leak oil at the timing cover where they meet the lower cover and engine block. The C280 has much more power, but they are both great power plants.

-Jim

evaporator issues plague all w124's!!

I can tell you this from experience.... :P

valve stem seals are a common M103 problem, they wear over the years and causes the car to burn oil in between changes. There are kits available to replace them

Well, I've never lost one in an early W124. We had an 87 300TD that we put 175K on over 13 years, got it with 100K, never had a problem with the A/C evaporator.

The replacement car, our current 95 E320 wagon, had the evap start leaking at just over 100K.

I've had 7 W124 chassis (86, 87, 87, 93, 93, 94, 95) over a period of 18 years, and only the 95 has had the problem...

Not to rule out your experience, but my observation and personal experience has led me to believe there is a much greater risk in the late W124 chassis.

Having grown up in Tucson, and lived in Scottsdale for 10 years, functioning A/C is very near and dear to my heart. :) All the above cars had working A/C while I owned them.

Jim

I think where you are matters more than what year it is. I've had a dozen cars over 20 years or so, mostly later cars, and have never had even a sign of the problem. It's a corrosion problem - doesn't seem to happen much in the desert.

very interesting.... i have never lost an evaporator either.....but now i have cars that I would spend the time and energy to change it...

Steamboat,

Have you fixed your oil leak yet?
Did the timing chain cover gasket fix the problem?

All

I have just purchased a 1989 300CE (M103) that appears to have the infamous timing chain cover gasket leak or may need a head gasket. Of course I am hoping for the former and would greatly appreciate any "insider" tips on replacement. I have ordered the shop manual on CD and hope to start the project in about 2 weeks. Also, any special tools I should definately add to my box? any/all help , suggestions welcomed

It appears that there was a recent thermal event with new radiator and water pump installed. + paint on the value cover has major peeling

Thank You

Oil Leaks
 

No, I never did get the chance to fix them on either car.

On the 95 E320, the dealer kept insisting but it was never significant enough to warrant the cost for fixing. Perhaps it lost 1/2 quart per 4k miles. The car lost a battle with a tire tread on the highway and my insurance company totaled it.

I sold the 97 before doing anything with it.

I pick up the 90 300E this Saturday. If I understand the M103 can still have timing cover leaks, but I wonder if the head gasket oil leak is common to the M103 engine.

It seems of the two leaks the head gasket leak would be the most expensive to repair.

i;ve never had a head gasket oil leak on a 103.....lost one to overheating..

timing cover gasket is a normal repair....takes a couple of hours to do...then the car should sit for a couple of hours while the gasket goop settles.

The 103 does leak from the head, same as the 104. For all intents and purposes the engines are essentially identical in terms of how the head leaks.

somebody on here had major success with some sort of pour in the engine head gasket repair