'51 Mercedes-Benz 170S

Eight years ago, I was introduced to a man who would ultimately become an incredible friend after realizing we shared a common love for cars and having graduated from the same DoDDS high school in Germany, albeit 50 years apart.

Behind his shop sat a 1951 170S, sans motor and transmission, but otherwise in good shape save for a small section of the trunk floor which will still need to be addressed. Being German myself, born and raised, and growing up around MBs (my uncle is a master mechanic, and taught me as I grew up), I had to have it.

All this time later, not too much has happened and it's now time to really get back into this project. I've begun the 6V to 12V conversion, and seeing as how there aren't too many independent circuits, the process has been easy. I just need to acquire 12V replacement bulbs for all around.

The main stumbling block that has dragged this project out for so long has been my inability to decide on a motor. The original motor and transmission combination would not be safe for road use here in Texas where everyone is flying, and I'd like to have this car as an occasional daily driver here and there. Resale value is moot to me as I don't believe I'll ever part with it in my lifetime, it's a handsome vehicle that just needs to be brought back and livened up a little bit.

Seeing as Corky (my aforementioned friend) has been working with Miatas since they first came out, his suggestion was using a 1.6 from an NA. I was on board with this until I fit one in and discovered an issue that would involve modifying the steering column as the exhaust is on the driver's side of the motor. Even a custom exhaust header wouldn't have enough space to avoid having to modify the steering column. I also received a lot of flak from purists about using a Mazda motor in a Mercedes (not that I really cared, it's ultimately my vehicle).

I looked for ways to keep it in the MB family, and while the M102 (4cyl) from a 190E sports passenger side exhaust ports, remedying the need for touching the steering column, those 4 cylinders are large for what they are, and finding one with a manual transmission is even more difficult. Part of me toyed with taking the DOHC M102.983 out of my '85 190E 2.3-16 for the 170S and tossing an M104 in 190E, but that motor is already perfect for that car; it just needs EFI and some quality forced induction (a project for a later date).

Then I remembered I have a spare 5.0L M117 motor that needs a rebuild, so I attempted to fit that in the engine bay only to discover it's long and wide, meaning the firewall would need to be cut into (something I'd actually like to avoid), so that put an MB V8 out of the question. I was all for adapting a manual to that motor, too.

I have a 13B rotary with transmission in my possession, and while that would fit easy and is simple enough to get running, I don't know if I would want to live with a rotary for something I could be dailying. Maintenance doesn't scare me, I'd just rather not have to engineer in potential problems (not knocking the 13B, they sound great and are a riot to drive in an RX).

So that leaves me where I am now; looking for a 4 cylinder motor that's compact, easy to get running, passenger side exhaust ports, and provides more than the factory 52HP!

The 3-cyl 1.0 EcoBoost was tempting, and there are plenty around for cheap, but without knowing how easy they'd be to adapt to a RWD platform (besides just sitting it in the trunk) and standalone management for the DI system, it seems it would be a daunting task to complete.

Now for some photos! They're a little older, but depict the car how it currently is:

When the 1.6 was test-fit, not quite centered either, you can see how the intake manifold is close to the fender and that's without the throttle body and any intake tubing:

Thanks for reading!

Looks like a solid start and another Texan to follow is always nice.  

What about a tdi with rwd adapter? 

Like a 1.9 R4? I thought about going the diesel route, as these were also available in diesel form back, then.

Admittedly, I don't know too much about VWs diesel lineup to consider them.

I did look at the OM601 which is a 4-cyl available in 2.0, 2.2, and 2.3 displacements, but they also end up being fairly wide, and finding a 4- or 5-speed manual is hard!

The OM616 found in the 240D here in the US is another option, but those are only punching out about 64HP! Later models I think hit 72HP.

If this were the 220-series (W187 chassis), I'd be able to choose from a world of inline 6s and even have an easier time with a V8, but I've got the smaller car which equates to an E-Class in the MB heirarchy.

Have you looked into fitting any of the BMW four cyclinders? M10 if you want carbs. M42/44 if you'd prefer EFI. They all have passenger side exhaust as well.  

Here’s a left field suggestion: how about a carb’ed 302 ford V8? They’re narrow and it might fit (although it’s hard for me to gauge how much room is available).It would certainly give it a street rod vibe.

It all based on what you plan to use the car for.  Based on what you have said that you plan to occasionally daily the 170 I'd Be leaning towards a  diesel powertrain combination.  Read up on what transmission will hook up to a VW tdi engine.  You can Pickup a used tdi beetle or similar wrecked or with dead transmission for next to nothing.  If it were me I would likely have to stay with the marque and find a m102 or m110 (not sure that wouldn't be a bit long).

German car, German owner. 

Use a German engine!

I’m kinda glad that Miata engine didn’t fit... that just doesn’t work for me. 

The Ford suggestion is a very good one. 

MTechnically said:

Have you looked into fitting any of the BMW four cyclinders? M10 if you want carbs. M42/44 if you'd prefer EFI. They all have passenger side exhaust as well.  

I thought of this too when I first read the thread, but given that both are canted over significantly, I'm not sure they would clear the hood on the right side. If they fit, they'd fit the character of the car well, I think, and manuals are easy.

I'm not a VW guy, but given the array of powertrain options and ways to arrange them, and that they're German, I'm inclined to think that's the first place to look.

Om617 doesn't fit? Turbo or non-turbo. 

Dodge 2.4 dohc

Gm 3.4 camaro engine 

Kia fe3 and mazda b2200 trans

All narrow and short!

Or, could you use a steer clear box on the firewall to fix the column isse?

Link to one manufacturer i found

If you want to go old school carbed solution: B20 + manual trans from Volvo 240? They have both exhaust and carbs on the cars right/passenger side. The BF230i from the 940-platform is of course a much nicer engine, but it is pretty large and taaaaall. A B20 with dual carbs would probably look pretty correct in the bay and fit the characteristics of the car.

How about a nice 2.3 Ford Lima, passenger exhaust, cheap, available, sturdy, manual, sounds like a tractor, plenty of aftermarket, carb or FI.  Don't shoot, I just happen to have a few.

Edit: Also look like they could have been from the fifties.

Have you looked at the Datsun L16/L18 series of motors? They look like copy of the MB motors and if you can find the SSS versions they have the dual side draft carbs.  

Or turbo an om616. 

I was going to suggest a B20 Volvo myself.  They are really tiny and even stock make over double the that MB engine did.

Was also thinking about a 2.3 pinto ford I4.

Here's a left field idea- flathead Ford V8?  They're pretty compact, will make plenty of power and torque for you, and sound great.  

Oh- and I daily drove an '83 240D with a 4 speed stick up until recently.  Despite being a pretty heavy car, the 2.4 N/A diesel moved it along pretty well.  I could hit over 80mph on flat ground.  I imagine the 170 is a lighter car.  Wonder what the stock rear axle ratio is (if you're keeping that).

Some people have turbo'd the 2.4 mercedes diesel.  If you keep the boost reasonable 100 hp is pretty doable, without holing the pistons.  

There was never a better car for an OM616/OM617 swap. Kind of a no-brainer to me, but it's also not my car. Anything to get this driving again will be amazing.

Here is another vote for a B20 Volvo with an overdrive gearbox to make up for the short final drive in the Benz. Much as I like the Datsun engine mentioned by jr02518, they have everything on the left side, so clearance problems abound.

I'd look at a 2.5 Duratec and manual trans. These cars aren't very heavy and a torquey 4 cylinder would move it out nicely. Find the appropriate Ranger and scavenge what you need for drive train and ancillaries.

Hell of a lot of feedback! I'll be honest, I wasn't expecting it to blow up so quickly!

Regarding the Ford 302, they used to be pretty plentiful around here with the M5OD box, but there is an array of more suited transmissions that would likely bolt up to it that would serve the car better. I also did have ideas of using a flathead V8, as that sound is just something you can't help but appreciate. The size is appealing too. In fact, there was a 170 that had a flathead V8 swapped in it, but I don't recall any further details.

BMW was another top choice, but parts are harder to come by here and I couldn't bring myself to part out an E30, no matter how rough of a shape it is in. While Mercedes is my number 1 brand, as a Bavarian-born German, I have a soft spot for the Bavarian automaker as well. Incidentally, it seems I was born almost halfway between either plant in Munich and Sindelfingen...

Carb'd or EFI is okay with me.

An OM616 with a 4-speed and a small amount of boost probably wouldn't be a bad choice at all; I believe the OM617 ends up a little long despite being a 5-cyl. It's interesting to see so many suggestions for a diesel and I can't deny my love for the sounds of these motors. My first ride home after I was born was in an 123-chassis 200TD wagon, and I always have pleasant memories of going to the local man-made lake with a raft up top as I got older. Miss the hell out of that car.

A diesel option puts me in an interesting position between VW and MB; I know next to nothing about VW, but I'm intimately familiar with the MB variants. I had a chance to snag an OM602 that had a 5-speed conversion, but it was sold before I could PM in time.

The rear end on this car is gone, in fact, the entire rear suspension is... it turns out it had been sold before I bought the car, and never pulled or disclosed to me. I came up to the shop one day to find my car without a rear-end. I had plans to adapt a beefier diff to the existing rear suspension setup, but now I need to engineer a new solution. Factory width of the rear track is 55.9" and I'd like to keep it in that area for aesthetics; use of the original 15" wheels with a 6.40x15 tires is also a must. Solid axle is likely going to be what's run, but I'm open to suggestions.

I'll be looking at adapting 126/R107 disc brakes up front, so I'll need to pop a wheel off my 500SE to study it and get the drum brake and other stuff off the front of the 170 to examine how the two knuckles/hubs compare.

In reply to volvoclearinghouse :

I saw your for-sale post last night, looked like a car with some great potential after some rust repair (which ain't a big deal back in Europe).

When I moved back to the states, I was wanting a 240D, or another 190E 2.6 since I couldn't bring mine with me from over there. Ended up finding a 500SE and a few years later grabbing my 190E 2.3-16.

In reply to yupididit :

Boi I didn't know you were on here.

Azryael said:

In reply to yupididit :

Boi I didn't know you were on here.

Who dis? Josh? Lol

I'm hoping to get the rest of wiring done for the basic stuff in the car this weekend, but I'm not sure I'll have any time to do so.

I still need to find the key for this car which is somewhere around the shop.

Need to grab my snake cam and look inside the fuel tank to see how it looks on the inside. Like to get that mounted back up too with a fresh fuel pump.

I've been sitting here in my office at work just mulling over the diesel idea some more. These cars were available with the OM636 which came in both 1.7 and 1.8L displacements making 38 and 39HP respectively. The 180D (W120, first of the ponton bodystyle, which I kinda wish this one was!) had a 1.8L OM636 cranked up to 43HP, but it had slightly lower peak torque and reached peak torque 500RPM lower than preceeding variants.

When I inquired about getting an OM636 for this car on a forum dedicated (but no longer frequented by anyone) to these early pre-war and post-war cars, I was offered to buy one in need of a rebuild for $5000, not including a gearbox! Such is the price for period-correctness, I s'pose.