W123 vs w124 in 2021
 

Ive owned 5 w123s and am looking at now getting a w124. We are talking something i will probably DD... But was just curious as to the driving styke 30+ yrs after these were built.

Furthermore... Im specifically looking at a te vs td. I have only owned diesels in the past and am not sure i sould be ok with the m103 motor.... How long do they last? Are they the same diy as their w123 counterparts?

Ive seen some posts on here from like 2002... But we are talking almost 20yrs later now.


Thanks!

I got 3 w124s. Wife and daughter drive theirs and I drive my w124 as a work beater about 120 miles a day. Once I got the issues squared away it runs drives great. Good mpg smooth quiet comfy ride. Personally I’d only get the 94-95 models. They seem to have stuff sorted out more than the earlier models. I’ve never owned a w123 so can’t compare. but I do know that they can’t touch a 124 on the gas mileage.

The W124 is quantum leaps ahead of the W123, they are even better then the W126 in my in ride, build quality and smoothness. The W123 is more charming tho.

93-95 have worse rust protection and bio wiring. 92 and older dont have these problems.

M103 was improved sometime in 89 and it no longer suffers from valve guide or camshaft wear. And not all pre 89 had problems.

M103 takes a lot more upkeep than a 616 or a 617.

I would say that a diesel w123 economy is about the same as a gas w124

An om617 will have the same mileage as the m103? Really?

Finding a td is gonna be challenging... I dont care about speed as much as simplicity to own and operate. (if it does 80 on the freeway without killing itself i am good).

I owned a 240d .. my god getting that to 70 mph was a herculean effort. My 300td (turbo) glides at 80mph.


Is it better to hold out for the om602/603?

My final question. Is it still diyable? How much more difficult are day to day items vs the w123?

Thanks

I went through this just recently and decided on a W124. My last purchase on a car this old was on my 80s 911, which although much more fun and athletic, is generally mechanically much simpler than the W124. I went with an M103 W124 with the cleanest body I could find at the cheapest price I could find, and I’m basically going through and refreshing everything plastic or rubber. Suspension, seals, etc. I figured that even well-sorted ones would need a fair amount of refreshing so I just went for something that was as cheap and nice as I could get, and I got lucky.

I went M103 because they take boost like champs.

But I’m also a DIY maniac and I will for sure rip that engine apart in my garage this winter, just like I dove into the suspension refresh totally blind. But it won’t be my first engine rebuild, and it wasn’t my first suspension refresh either so, I figured it out. My guess is that the W123 might be easier to repair, just based on that rear multi link suspension. But take that with a grain of salt.

The W124 will be a better daily, but with the age of these cars, unless someone went through and replaced all the bushings, even if it drives well, expect to do the subframe, bushings, tie rods, trans mounts, and a bunch of other while you’re in there stuff, if not all at once, over time. Especially if you want it driving tight.

Best of luck and enjoy.

Having owned and driven W123 240D, 300D Turbo, 300TD, W124 300TE (M103) and 300E (M104 3.2L) I'd prefer a W124 all day, every day as a DD and preferably the M104 version. As a classic once in awhile driver I'd prefer an uber clean W123 300D Turbodiesel.

My $0.02.

It's not just the engines but the chassis. W124 is more aerodynamic and has longer axle ratios than the w123. That's why when cruising the w124 m103 will have similar milage to w123 om617. But in the city the w123 om617 will be more economical than w124 m103 because in the city aerodynamics and axle ratios don't matter that much.

W124 suspension is more complex and harder to maintain than w123. And again om616 or 617 is much easier to maintain than the m103. If you want an easy and reliable engine in a w124 then get a om601 200D. But other diesels are good as well

The m104 is the bees knees tho. Powerful rev happy smooth running engine

What kind of issues/reliability proboes will i run into on a 103/104?

On my 617 i have rebuilt injectors, done valve adjustments.

What kind of maintenance do you need to do on a 103/104 that isnconsidered 'more taxing to maintain?'

Thanks

It should have the updated wiring harness, updated throttle actuator, updated ovp, updated head gasket. If not you’ll be the one replacing those parts. Not really expensive or hard to replace

Smog pump bearings seem to not last long.

I agree with you 100 percent

To add to mr. Speednjay's list are plug wires, cap, rotor, spark plugs and sometimes ignition coil (later m104 have coil-on-plug ignition), m103 timing chains wear out by 140k miles, early 104 motors like to break the EZL and used working ones are worth a lot of money, fuel injectors, if k-jet then the EHA valve can go sometimes, head gaskets don't last 100k on m104 and m103 gasket is a little better but not much. Fan bearing brackets like to go too on both motors.

Thanks for all the feedback. Im going to go with an m104 unless i can find an om603 (super unlikely).

Most of these issues seem very fixable. Probably wnat to make sure the head gasket and wiring harness have been replaced... The rest seems very doable.

Wiring harness is that hard to do. Maybe a 30 min job. If your good with a wrench the head gasket isn’t that tough either. Just saying