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It all started one faithful evening. I was doing my all-too-frequent search for any sort of wagon in the Northeast to occupy my time over winter break. Then I saw it.
"So it needs a little bit of TLC," I thought. "What could go wrong?" as I stared down those 3 massive letters following the "price". Immediately, I sent a message. The next day, having received a response, I practically begged the owner for his venmo so I could secure it. How I would be getting it from where it sat in Vermont to Southern New York from where I was in my dorm room in Ohio; that became a challenge for another day.
But, a few phone calls in between final exams and classes eventually yielded this. The "mom-spec" wagon was mine.
Now, as there are much more important (and interesting) details to cover, I'll summarize some of the "boring" stuff. It showed up, barely starting with a jump, whereupon I immediately drove it around the block for a test-drive. The driver-side suspension had completely failed. The rear self-leveling air spring was dead. Front coil spring dislodged from its mount. It was squatting on one side. So I replaced the rear spring, had a local shop install the new front coil and mount, all while thinking "this is a piece of cake!" Not so fast.
Then I got the call, the crucial call. "We have to show you something on the car, when can you come in?" P1208 was the code on the check-engine light that I had assumed was something simple. Moving on.
So, now I have about $2,500 in a wagon that was just diagnosed with a terminal heart-condition. I was not that worried about the money, but my dream was in jeopardy. My mom-wagon was just starting to come together, only to fall apart completely. Luckily, I have crazy friends.
"Have you ever done a balance shaft on an M272?"
"Sure, but usually I just replace with an M273."
*Google search and rabbit hole of learning ensues*
"Ok. When?"
SE4TS7 is born.
I immediately got to work researching how this could come together. Again, not getting bogged down this details, my findings were that the M273 was pretty much a drop-in-swap. So, I shipped it off to Cleveland, Ohio to Euroformance where the surgery would be taking place. Once I was back at university, sourcing the engine would occur. A $950 M273 was located in the Pittsburgh area, pulled out of a 2008 E550 with 115k miles that was wrecked.
New motor mounts and front axles were added into the mix. The M273 dropped in, as expected. From that point forward, there were two main things to cover now that, mechanically speaking, the wagon now had a new heart. The challenge was to get it beating.
Full transparency, I am a mere dreamer, and a spectator, as I did not actually perform any of the work involved in the swap. But, I have followed along as I wanted to be more involved than just writing a check, so to speak. With the new engine, a virginized ME9.7 ECU was necessary, which was ultimately programmed with an Autel setup. As far as I'm aware, with the autel setup it was a pretty straightforward reprogram (oxymoron, I know), as the pairing of the M273 + 722.6 + 4Matic was factory, minus the wagon body style.
The last piece of the puzzle, thus far, was perfecting the transmission linkage. The V8 required slight adjustment of the linkage, so now the gear selector was not lined up on the shift bezel. So, the shift linkage was shortened to accommodate. It now lined up perfectly!
As I am writing this on March 9th, 2023, I have now put about 260 miles on the swap. With the exception of an unfortunate flat tire and a slightly severed (now repaired) radiator hose because of contact with the serpentine belt, it has been flawless. Later today, I embark on its first real test, hauling from Cleveland back home to New York for spring break. I am cautiously optimistic, we'll see.
Long time reader, first time caller. Hopefully someone enjoys this write-up of my 7 seater. Follow me on instagram (xjhigg) too!
Last edited by xjhigg; 03-09-2023 at 09:28 AM.
Reason: Forgot to add detail
On the radiator to belt contact, the E500 and E550 use a larger (thicker) radiator that was moved forward away from the engine about 1" compared to the V6 models. You might want to source that V8 radiator, especially before summer.
Thank you! I am looking into swapping the radiator as it is definitely a good idea like you said. So far I have put just over 2,500 miles on the build and it's been great!
03-09-2023, 09:22 AM
SE4TS7 (5.5L M273 V8 Wagon Swap)
Follow me on instagram (xjhigg) too!
