Good or bad idea? Mercedes W123 as a daily?

Hey all. I've had my 2006 Honda Accord for the past 8 years, coming up on 9 years as a daily driver. It has been a great daily, has almost 200k miles on it, with a 5 speed manual transmission (2.4L 4 cylinder K24 variant). There is nothing wrong with the car, and honestly, its chugging along as expected of a Honda from that era.

However, I have been lusting over the diesel W123's on FB marketplace. A part of me wants to daily one of these beauties. I've never had a diesel before and I am kind of interested in giving one a try. I figure the W123 is a pretty good platform to give diesel a go.

The other part of me says I am absolutely insane for thinking of getting rid of a nice, reliable, modern-ish daily driver for a 40+ year old European barge. I have read about how they are reliable, but does that really stand true even today with how old these things are? Would I be dumb for getting into such an old Euro car as a daily driver?

Any insight into how bad of an idea this is or whether I will be *mostly* okay is appreciated!

I would keep the Accord as backup. I do this with my ~30 y/o BMW. If that's not an option... I'm gonna vote nah. E36 M3 is stressful. 

The other part of me says I am absolutely insane for thinking of getting rid of a nice, reliable, modern-ish daily driver for a 40+ year old European barge.

2006 Honda Accord - 191″ L x 72″ W x 57″ H

W123 Mercedes - 186" L x 70" W x 56" H

Maybe you need to look into a W126 if you really want a barge ;)

BTW I put 12k miles on a W126 500SEL in 2015. It only needed a fuel pump It had 190k miles when I sold it. 

If we know the W123 doesn't have algae in the fuel then I'd be pretty comfortable driving it to the moon and back(~440,000). I have road tripped my (then)OM617 powered W116 chassis all over the east coast and I'll do it again. These cars are electrically very simple, mechanically very robust and the vacuum system is terrifying. You may not have functioning HVAC or door locks, and you may have to open the hood to push the manual stop button on the injection pump, but the car will continue to run foreve.r

On W123, make sure the front sway bar is not rusted. PITA to change and the do rust and break. 

Slippery said:

The other part of me says I am absolutely insane for thinking of getting rid of a nice, reliable, modern-ish daily driver for a 40+ year old European barge.

2006 Honda Accord - 191″ L x 72″ W x 57″ H

W123 Mercedes - 186" L x 70" W x 56" H

Maybe you need to look into a W126 if you really want a barge ;)

 

Huh, well will ya look at that...all this time I thought the W123 looked larger than my Accord but I guess it really isn't!

EchoTreeSix said:

I would keep the Accord as backup. I do this with my ~30 y/o BMW. If that's not an option... I'm gonna vote nah. E36 M3 is stressful. 

That makes sense, thank you for your insight!

buzzboy said:

If we know the W123 doesn't have algae in the fuel then I'd be pretty comfortable driving it to the moon and back(~440,000). I have road tripped my (then)OM617 powered W116 chassis all over the east coast and I'll do it again. These cars are electrically very simple, mechanically very robust and the vacuum system is terrifying. You may not have functioning HVAC or door locks, and you may have to open the hood to push the manual stop button on the injection pump, but the car will continue to run foreve.r

I see, so the vacuum system is a bit of a nightmare but the rest of the car is not so bad?

I dd'd a om617 manual 240d from 2014 to 2017 in Southern California. Only time I didn't drive it was when I had my kid with me. It was a euro model that was bare bones, no ac even. 

I say do it but if you need to do any highway driving, you'll hate it. 

Japanspec said:

I see, so the vacuum system is a bit of a nightmare but the rest of the car is not so bad?

I race a W123 and a W116. They are pretty stout. A very common failure is the vacuum operated engine kill switch. The 45 year old vacuum lines get very brittle and crumble in place.

You'll be mostly okay. 

-Buy a vac gauge to trouble shoot the vacuum lines

-Get sheepskin covers for the MBTex seats

-Get a turbo if possible, manuals are desirable as well

-I'm a sucker for the station wagon in blue. So much room for activities!

It's the law in NY, CT and VA that you have to dress like a Vampire Weekend video if you take it to Cars and Coffee.

I'd get a gas one if possible. And if you must get a diesel, find one with the om617 swapped in.

Very slow, especially on hills, they always need work of some type, some of the parts can be expensive, and they take some special tools to work on.  Other than being too slow for modern traffic I don't see any reason not to daily drive one though, and they are very easy to work on.  If you drive on the freeway in traffic (especially with metering lights) it will be dangerous, but otherwise I say do it.

Thanks guys for your insight! Im no stranger to slow, as I have a kei truck, so they must be similar and/or the W123 a bit faster. 

Any reasoning for the gas one vs diesel?

yupididit said:

I'd get a gas one if possible. And if you must get a diesel, find one with the om617 swapped in.

I had a few W126s in college, as my commute at the time was 45-minutes each way on the highway and I was poor. If you're looking for a land barge, the W126 is your answer. W123s aren't that big. The OM617 isn't actually that smooth on the highway; later cars had the six-cylinder OM603 which was way better in every way except supposedly reliability, though mine was rock solid over plenty of commuting miles.

They don't actually get very good fuel mileage. I averaged low to mid-20s in mixed driving, which was great for a giant car in the 80s, but don't expect VW TDI fuel economy here. 

As others have said, the vacuum system sucks but the basic mechanicals are simple and easy to keep running. Parts range from dirt cheap to obscene and unavailable. I remember buying an $800 brake booster and having a custom radiator made by a race shop because both parts were basically unobtanium. At the same time, brake pads were like $3 or something crazy cheap. The cars are generally easy to work on, but you'll need a few specialty tools here and there. They're hilariously overbuilt, and drive far more modern than they are. 

That said, they make far better beaters than perfect cars. It's the kind of car where restoring it to a B+ condition costs $, while restoring it to A- condition costs $$$$$$$$$$. 

Here's my 300SDL:

Japanspec said:

Thanks guys for your insight! Im no stranger to slow, as I have a kei truck, so they must be similar and/or the W123 a bit faster. 

Any reasoning for the gas one vs diesel?

yupididit said:

I'd get a gas one if possible. And if you must get a diesel, find one with the om617 swapped in.

Diesel 123 are just slow af. Unless they're manual and have a turbo.

If mine wasn't modded with a swap and vgt turbo with a manual trans, I would not have daily drove it. It still topped out around 75mph lol

It'll do 90 on the interstate, but getting there takes a while. My gutted car ran the quarter in 19.7 @ 67mph

In reply to Japanspec :

I wouldn't get a gas one, old fuel injection is too complicated and they have too many expensive and hard to find parts.  The diesel ones are just really slow though.  Some of the places I drive have metering lights with a very short merge that takes a full throttle pull to 90mph in my Boxster just to merge safely, so trying to do that in an OM617 Mercedes would end badly.

In reply to Tom Suddard :

The OM603s have issues with the cylinder head and vacuum pump, although a lot of them are fine.  The original sdl radiator is long NLA, but I think you can either get a Chinese aluminum one for $350 or a better quality one for $800 last I checked.  I had a 300sdl for a few years and wasn't bad, the head gasket eventually started leaking (although it still ran fine) and I sold it because I wanted the space for some other projects.

I daily'd a W210, and my friend as a W126.  Both were bulletproof tanks that refused to age, decay, or show wear.  His has somewhere north of 400k and I finally sold mine with 210k, and the leather still looked nearly new.  I don't mean "it still looked pretty good," I mean it had zero wear except one small crease on the driver's seat.

Parts are getting harder for the older ones, but I wouldn't hesitate to get a diesel.  They aren't fast, but they tend to be remarkably long-lived.  Add turbo if needed.

The manuals don't really make for exciting driving.  They're a little floppy, but try getting parts for a 722.x transmission from the 80s.  Merc autos are best just scrapped when they start to die.  Very hard to get a rebuild right.  They're typical German engineering, and the originals were assembled by very precise machines.  It's hard to replicate that on a bench at Jimmy's Tranny shop.

Sub out modernish Accord for very  old German car. What could go wrong!
 

GRM says Do it! 

yupididit said:

I'd get a gas one if possible. And if you must get a diesel, find one with the om617 swapped in.

You don't have to find one with the om617 swapped in, just get one of the many that came like that already. At least in my area it's a lot more common to find a 300 with a turbo for sale than any other flavor of W123. 

Curtis73 (Forum Supporter) said:

I daily'd a W210, and my friend as a W126.  Both were bulletproof tanks that refused to age, decay, or show wear.  His has somewhere north of 400k and I finally sold mine with 210k, and the leather still looked nearly new.  I don't mean "it still looked pretty good," I mean it had zero wear except one small crease on the driver's seat.

Parts are getting harder for the older ones, but I wouldn't hesitate to get a diesel.  They aren't fast, but they tend to be remarkably long-lived.  Add turbo if needed.

The manuals don't really make for exciting driving.  They're a little floppy, but try getting parts for a 722.x transmission from the 80s.  Merc autos are best just scrapped when they start to die.  Very hard to get a rebuild right.  They're typical German engineering, and the originals were assembled by very precise machines.  It's hard to replicate that on a bench at Jimmy's Tranny shop.

They make aftermarket controllers for the 722.6 now that will bolt to an om603 and can be bolted to an om617 or most other Mercedes engines, and they made so many of those that I'm sure parts will be available for a while.  Not a simple stock replacement but it's at least a way to keep the car on the road if you want to.

In reply to EvanB :

The other problem with a 240d is they really aren't geared to drive over about 70 mph.  

In reply to Tk8398 :

I like that idea, but I'm just not a big fan of the OM617.  It's fantastic for longevity, but expensive to get it to make any reasonably fun power.  OM606 was the real gem for me.  It was the last of the really tank-ish reliable ones that was still relatively simple, and easy (but not cheap) to make big oomph.