W126 gen2 vs w124 diesels - PeachParts Mercedes-Benz Forum

JHZR2 · #1 03-18-2022, 10:07 PM

Looking to maybe add one more diesel to my collection. I’m a great w123 fan (own two), own a w126 and w140; never have had a w124, have prior experience with w210. So that sets the stage.

Looking at OM60x cars, so the gen 2 w126 vs various w124 cars, but primarily the 2.5 turbo 300D.

The w123 was an evolution towards perfect based on cars from the 1950s. I love them. I love the almost remnant fins on the back.

The w124 is boxy and modern, a vast departure.

The w126 seems like a cross between the both, more classic lines, space, comfort.

While my w140 is comfortable and posh, it lacks something of the older cars. It is a great driving car all around, don’t get me wrong, but it’s a little bit more “engineering the ultimate car”, less “classic Mercedes feel”.

Is the w124 more like the w123 or the w140 (I get it these are different classes, but the w124 is a mini w140, or vice versa).

I know the woes of the om603. Does the 2.5L 603 have the same head issues? Are there reasons to avoid the 2.5? I’m assuming that if MPGs are desired, the 2.5L w124 is the way to go (I have three kids so I’m not looking for a 201)… is it consistently a >30MPG car? My w126 3.5L is a 28ish mpg car on the highway, my w140 3.5L is a 26ish Mpg car on the highway..

Is working on a w124 2.5L harder than a 617 in a w123, or a 603 in a w126 or w140? The w124 strikes me as more compact in the front.

Creature comforts are another thing… my 1991 w126 has independent amps. It has good enough sound for me. My w140 I really like the sound of the stock system. Does a w124 of the same era (early 90s) with high line OE stereo perform more like the w126 or w140?

Is the w124 as roomy as my w123, or bigger or smaller.

I know I’m jumping all over, comparing different cars, different classes and sizes of cars, but I’m asking to compare what I know and can reference against.

Which would you buy? A 1991 SDL or a 1990 300D 2.5? (Forget rod bending).

Thanks!

Bengoshi2000 · #2 03-19-2022, 08:18 AM

I've had a 1991 300D 2.5 for about 5 years. Previously owned an '84 300D (sold due to rust issues). Never drove a w140. My answers are inline below:

Quote:

Originally Posted by JHZR2

Is the w124 more like the w123 or the w140 (I get it these are different classes, but the w124 is a mini w140, or vice versa). It doesn't drive or ride like a w123 (I owned one previously). I find it to be an order of magnitude more responsive, both at the throttle and in the handling... it's more "sporty" than the SDL. I test drove 3 w126's. Two were 350's one was a 300. The w126 is much more comfy on the highway. Smooth as glass. It's a bit hoopty around town.

Does the 2.5L 603 have the same head issues? I don't think so, and the 2.5 is the om602... 5cyl vs. 6.

I’m assuming that if MPGs are desired, the 2.5L w124 is the way to go. I get low-mid 20's with my current driving (6 mile round trip to work). All city driving. I'm getting about 350-370 miles per tank. Now when I put it on the road it consistently gets 32-35 mpg. The best I've ever gotten is 38.

Is working on a w124 2.5L harder than a 617 in a w123? I really can't tell a difference. There's more vacuum lines to follow around. But I feel like it's a wash between the two.

Creature comforts are another thing… my 1991 w126 has independent amps. It has good enough sound for me. Can't say one way or another. The stock Becker in my w124 was shot... as were the speakers. I ran new speaker wires front and back. On the one or two occasions the the stock Becker was in the mood to work, I thought it sounded like a decent 1991 stock system. My w123 had an aftermarket head unit when I got it. YMMV.

Is the w124 as roomy as my w123, or bigger or smaller. About the same. When I drive the "lunch crew" It can hold 5 adults (3 in back, 2 in front). I'd say that would be ok for say an hour or so... wouldn't want to do that for a long trip. 4 adults is ideal.

Which would you buy? A 1991 SDL or a 1990 300D 2.5? (Forget rod bending sorry, can't overlook that, too much of a risk imo). Initially, I wanted a w126 SDL. Couldn't put my hands on one that 1) wasn't a 350, 2) didn't have emerging rust issues (undersides of doors and around rear window), 3) had a service history. I could find 2 out of 3, but that was it. Then I found my 1991 300D, original owner, 113k miles, no rust. I didn't really want one, but it was simply to good to pass up. I have yet to be disappointed by it.

Thanks!

FWIW, If I could ever put my hands on a w116 that is equivalent in maintenance, lack of rust, etc. to my w124, I'd buy it.

dieselbenz1 · #3 03-19-2022, 10:25 AM

I've driven all owned a 1980 300 tdt for 20 years and have a 124 for the past 18 years. Maintenance and working on the 124 2.5 turbo is enjoyable will all that extra space compared to a 123 or a 603. I've deleted all of the egr vacuum lines so no issues and the doors are on its own vacuum/ pressure system so easy to work on vs 123. Oh and no more valve to setup.

The audio in any 30 year old car with original speakers sounds poorly in minus 30 degree weather but mostly the lower frequencies. Not certain if independent amplifiers would help any but if I don't like what I hear I take out my hearing aids haha.

Sitting in and driving a w124 is a real pleasure it feels solid, steering box is self correcting so never any play. Lively cars that love to be thrown into a tight corner that multi link rear suspension is great.

I just am seeing a tiny bit of rust developing on the drivers front fender unlike my 123 that rusted from the inside out. But nothing compared to my old w210.

W124 is an E class so large differences between S to E class. Preformance packages are more readily available for the w124 if that's important?

blue85' · #4 03-19-2022, 12:00 PM

I've been fortunate enough to drive all three. About 100K in 3 various W123's, 10K in a W126, and 60K in a W124.

The 124 is the best drivers car hands down. The 84 300TDT was second in my mind. It handled quite well.

The 86 300SDL is best on the highway. A bit cumbersome around town by comparison to ether of the others.

The W123's are magnificent in their simplicity, and dependability. Love them for that and, and for their 'older' feel. My W123's have had the most comfortable front seats. The seats in my W126 are not anything special. I adjust to them, but they are the worst of the bunch in terms of comfort.

The W124 is a magnificent car, but it is more finicky. Mine is a 300E, so many of my challenges are not relevant to the diesels... but the rear suspension is the same and if it is right, then you are all set. .. I've had mine aligned twice, and they got it so wrong both times that I have learned to do it myself.

Also the W124 is significantly smaller inside than ether of the other cars.. I'm 5'10" and I have the seat adjusted all the way back. If you fit in a W124, and find a good example, it is a magnificent car... But not quite a bomb proof as the W123, and much more athletic than ether of the others. .

JHZR2 · #5 03-19-2022, 12:34 PM

Quote:

Originally Posted by blue85'

I've been fortunate enough to drive all three. About 100K in 3 various W123's, 10K in a W126, and 60K in a W124.

The 124 is the best drivers car hands down. The 84 300TDT was second in my mind. It handled quite well.

The 86 300SDL is best on the highway. A bit cumbersome around town by comparison to ether of the others.

The W123's are magnificent in their simplicity, and dependability. Love them for that and, and for their 'older' feel. My W123's have had the most comfortable front seats. The seats in my W126 are not anything special. I adjust to them, but they are the worst of the bunch in terms of comfort.

The W124 is a magnificent car, but it is more finicky. Mine is a 300E, so many of my challenges are not relevant to the diesels... but the rear suspension is the same and if it is right, then you are all set. .. I've had mine aligned twice, and they got it so wrong both times that I have learned to do it myself.

Also the W124 is significantly smaller inside than ether of the other cars.. I'm 5'10" and I have the seat adjusted all the way back. If you fit in a W124, and find a good example, it is a magnificent car... But not quite a bomb proof as the W123, and much more athletic than ether of the others. .

The point about interior space does concern me. I’m 6ft 4 or a bit taller. My head touches the headliner on my w123 cars, but I’ve been used to it for the last 20 years…

The fit is somewhat better win the 126, and much better in the w140.

The w140 is just so big, and as a driver, while great on the highway, is too low of MPGs for one rider.

The risk is not fitting well in a w126. That said, there are lots of Germanic people who are my height, and a 124 is a pretty big car in Euro standards… so I’m kind of concerned about fit…

I’d imagine the w124 is less electronically finnicky than my w140.

It’s really a question of if I buy another w126 vs a w124.

87tdwagen · #6 03-19-2022, 05:52 PM

Given your size, I think the W124 sedan would feel like your W123, a little tight. The best W124 diesel option may be the 1987 TD. The wagons are both taller, and have more headroom than the sedans, and given the cavernous interior volume and airiness, you'll feel like you are inside a W126, but at the actual and far more tossable W124 size.

I know they are rare, but the earlier W124 OM603 diesels are IMO better built, better parts quality and and have better rust proofing than the later W124s. The OM603 makes them very peppy, but not as fuel efficient as the OM602. I get a steady 30mpg hwy at 80mph in the TD. Worth the search for a clean keeper. Otherwise stick to the W126. Personally I'm a big OM603 fan, so the 86-87 are my favorites.

JHZR2 · #7 03-19-2022, 07:37 PM

Quote:

Originally Posted by 87tdwagen

Given your size, I think the W124 sedan would feel like your W123, a little tight. The best W124 diesel option may be the 1987 TD. The wagons are both taller, and have more headroom than the sedans, and given the cavernous interior volume and airiness, you'll feel like you are inside a W126, but at the actual and far more tossable W124 size.

I know they are rare, but the earlier W124 OM603 diesels are IMO better built, better parts quality and and have better rust proofing than the later W124s. The OM603 makes them very peppy, but not as fuel efficient as the OM602. I get a steady 30mpg hwy at 80mph in the TD. Worth the search for a clean keeper. Otherwise stick to the W126. Personally I'm a big OM603 fan, so the 86-87 are my favorites.

What year did they reduce rust proofing? That is reasonably important to me.

I’ve seen some 603 w124 cars. Their rarity and premium isn’t worth it to me. What I’ve seen is that 270k+ mile examples are selling for about the same as 150k+ mi examples with the 2.5.

87tdwagen · #8 03-19-2022, 09:35 PM

Quote:

Originally Posted by JHZR2

What year did they reduce rust proofing? That is reasonably important to me.

I’ve seen some 603 w124 cars. Their rarity and premium isn’t worth it to me. What I’ve seen is that 270k+ mile examples are selling for about the same as 150k+ mi examples with the 2.5.

From what I have seen, the 86 thru 89 models had the spare no expense approach, with body wax in near all cavities including auxiliary suspension parts such as control arms. 90-92 Some of the auxiliary items came unprotected. 93-95 had even more loss of wax in the body shell, and I suspect material changes to the body shell steel eliminating the galvanized quality of the earlier bodies. Throughout the years there were many material changes to paint, moving away from solvents to water based by the last few years of production. You could argue either way, but IMO the earlier solvents paints were more durable and better at rust prevention.

Engines have their fans, a inline 6 is harmonically superior to all other engines albeit a V12, which is king of smooth. The OM603 when in proper form, runs like a Singer sewing machine. It is torquey and smooth. You get fast acceleration out of the gate, it compares favorably against comparable sized models both in the city and on the highway. You get the performance and durability at the expense of some economy compared to the inline 5 versions. In the end it all depends on how you plan on using it, how much city, hwy, and the traffic or required merge speeds needed in your area. They are also durable, to your point, the OM603 models you are seeing have nearly twice the mileage and still ticking (although that just might be a lifter)