How Bad Could a Mercedes-Benz Diesel-Powered Mustang Be?

Story by Eric Road • Photography Courtesy LeMons

Ford built roughly two million Mustangs in the 1960s, so it seems only natural that a few particularly battered old pony cars end up racing in the 24 Hours of Lemons. Among those half-dozen or so early Mustangs, quality has varied greatly. Toward the bottom end of “functional” (but the top of end of “awesome”) lies the ’68 Mustang of The Mild Horses.

We first saw the Georgia-based team at Road Atlanta in 2017, when they ran the green Mustang basically as they bought it–which is to say “pre-ruined.” Its previous owners had swapped in the big-block 460 and C4 automatic transmission from a late-’70s Ford pickup. Naturally, they left the original six-cylinder car otherwise alone, including its four-wheel-drum brakes.

It’s probably fortuitous that the 460 grenaded before the team could explore the car’s braking deficiencies. Having tinkered with some diesels before, they vowed to return with such a powerplant.

Not only did they come back with a straight-five Mercedes-Benz diesel in the ’68 Mustang, but they had also basically mounted the engine in the passenger seat. Why? Your guess is as good as ours, but they rebuilt the firewall around the school bus-sounding Benz mill, then built an adapter to use a T5 transmission.

The spatially aware reader will wonder how any of that worked. In a word: poorly. The transmission tailshaft sat well behind the driver, and the driveshaft ended up about a foot long. This meant the shifter was also behind the driver, so they made a literal shift lever.

None of it worked quite right on account of the diesel Mustang’s build period of just a few weeks, but The Mild Horses promised to return later this year with the bugs worked out and the lever-shifted Mustang sputtering along.

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spkorb
spkorb New Reader
1/18/20 12:51 p.m.

I used to think the Suprang was an inspiration, but I was just riding a wave of Harbor Freight welders and old steel oxidizing in back yards across America.  I'm so very happy at how it all turned out.

_
_ Dork
1/18/20 2:53 p.m.

There was a guy with a 1jz automatic suprang at our autocross this year. Wretched gearing. Wouldn't spool the turbo with the converter he had in it. Sounded cool though, and weird hearing that noise from a gen 1 Mustang. 

msterbeau
msterbeau New Reader
1/18/20 5:45 p.m.

I would comment on how shoving the engine so far back would make it infinitely more difficult to develop the drivetrain and fix problems - but I'm pretty sure that was the whole point.

buzzboy
buzzboy HalfDork
1/19/20 8:25 a.m.

I asked why they put a complex shifter and manual trans in the car. Didn't get an answer. They spent multiple hours during track time diagnosing their clutch then gave up and drove in one gear. Mercedes 722.3 is not a good transmission but they are stone reliable.

yupididit
yupididit UberDork
1/19/20 8:33 a.m.

I'm assuming it was an om617 because that doesn't look like an om605. Is there really no space for a 617 in a first gen mustang? 

NickD
NickD PowerDork
1/19/20 8:35 a.m.

The weird thing is, I've seen a couple '60s Mustangs with Mercedes diesels in them.

buzzboy
buzzboy HalfDork
1/19/20 6:57 p.m.
yupididit said:

I'm assuming it was an om617 because that doesn't look like an om605. Is there really no space for a 617 in a first gen mustang? 

Also because we didn't get OM605s in the US. An OM617 fits well in a classic ford engine bay. I've seen a few other swaps that were non-invasive.

noddaz
noddaz UltraDork
3/10/20 8:52 a.m.

Putting a Mercedes-Benz diesel engine into a Mustang is peak LeMons ingenuity.

I am not knocking these guys because they are racing and I am not, but I am not sure if that is a proper description.  winklaughsmiley <----- (This IS smiles, laughter ect on my part.)

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