Day 6 (and counting) of our 1-day engine swap

Every day I show up to the shop with a promise: “You’ll drive your car today.” But each night I go home without even hearing it run. How much longer will it be until I just don’t want to go to the shop anymore?

At the shop sits my rather clean E36-chassis BMW sedan, still waiting for a heart. That heart is about 20 feet away: a donor 2.5-liter BMW M50 drivetrain we pulled from my old rust-bucket E36.

Our publisher, Tom, had gathered the entire editorial staff for a day of hard labor disguised as a team building exercise, where he planned a “one-day engine swap” to combine my two BMWs into one.

I thought that Tom was a bit too optimistic about our “quick and easy one-day engine swap,” but he was able to sell me on a second shop day to finish it up. We planned to spend a couple hours over the weekend to prep the drivetrain before the day we would put it into the car and finish the swap.

Wouldn’t that turn it into a three-day engine swap? Who cares? I was just excited that the car would be done and I could drive it again.

So Tom and I arrived at the shop early on a Sunday morning and got right to work trying to clean 30 years of oil off everything.

This would have been a grueling job at home, but the shop has a Kärcher heated pressure washer that made quick work of it all–just one of the perks of the job.

Next, we needed to remove the old exhaust manifold, which was cracked and leaking. I’m on a tight budget thanks to the $2000 Challenge, but I figured I’d splurge on this huge quality-of-life (and -lungs) upgrade and buy a cheap eBay header for $154.99.

Photograph by Tom Suddard

I’ve never had to remove a manifold before, and Tom kept reminding me that snapping a single stud would ruin our day. Thanks, buddy, no pressure …

Fortunately, everything unscrewed without too much drama–credit to my luck, skill and of course a heavy dose of CRC Freeze-Off.

I wasn’t about to reuse the hardware I’d spent 30 minutes wrestling out of the head, so I faced a decision: Spend probably $50 at the hardware store trying to find what I needed, or use BimmerWorld’s $95 Header Install Kit to make things easy. The kit contains new gaskets and a full set of the correct studs and locking hardware. I’ve got room in my Challenge budget, so I splurged on the right stuff.

Photograph by Tom Suddard

Broken manifold out of the way and hardware ordered, our final item on the prep-day checklist was “Secure the oil pump nut.” Apparently, these engines have a weak spot: Rapid rpm changes can cause the oil pump gear nut to come loose, resulting in complete loss of oil pressure. I don’t know how familiar you are with engines, but loss of oil pressure is bad. There are two good ways to properly secure the nut, but only one of them is free: Weld it on.

Of course, before we could even get to the oil pump and its nut, we had to remove the oil pan. The process was easy, but the result was not: This was the nastiest oil pan I had seen in my life.

Photograph by Tom Suddard

Between Tom and I, we easily spent the better part of an hour with our CRC SmartWasher BenchtopPro cleaning off as much of the caked-on oil as we could. Once we had a clean pan, it was pretty easy to weld the nut, then reassemble things with a fresh pan gasket. (I’m fancy, I know.)

The hard part was done, or so I thought. This was now a pristine drivetrain ready for installation. So, we made plans for later in the week to rope in our videographer, Chris, to film the drivetrain install and first startup. In our infinite wisdom, we scheduled day three of our one-day engine swap on an afternoon that we all had plans, so we would only get about 3 hours of shop time before we all had to call it a day. Piece of cake, right?

It was not a piece of cake.

Photograph by Chris Tropea

We left the shop later than we had planned to, and all we did was bolt the engine and transmission to the chassis. It felt like the car was fighting us at every step, and all we were trying to do was put in an engine that came in this chassis from the factory. I’m a pretty upbeat guy, but this was the first day I drove home from working on this car wondering if all this effort was really worth it.

Almost two weeks later, we finally found the time to get the band back together again for day four of our one-day engine swap. At least the engine was in the car!

We started by installing the new exhaust header that I had ordered, and of course it didn’t want to fit well. The BimmerWorld Header Install Kit and a mallet ended up being the right tools to install the poorly made header, but this took much longer than we’d expected. Thankfully the back half of the factory exhaust bolted right to the cheap header, so at least we could cross that off our list.

Photograph by Chris Tropea

The next order of business was to plug the engine harness into the chassis harness and hope everything would live in harmony. This didn’t seem hard: It’s basically two giant round plugs and a battery cable, which only took us a few seconds.

We plugged everything where we thought it would logically go, turned the key, and nothing. No fuel pump, no crank, nothing.

Photograph by Chris Tropea

Turns out the previous owner had removed a fuse, and we finally got the fuel pump to prime when we turned the key. Success? Sort of, if our goal was to find every place that the car could leak fuel from. I started cleaning the spots where fuel had ended up on the ground, while Tom ordered some fuel hose from the local part store, and we poked around looking for more leaks until the hose arrived.

Not long after fixing the fuel lines, we had to wash up and head to dinner for a birthday celebration, where not even the joys of Indian food and ice cream could take my mind off of another long day with minimal progress.

Surely if we had just put this many hours into the rusty E36, it would be further along than this car, right? My mind papered over the Flinstones-style holes in the floor, and all I could remember was the fact that it ran, no, it drove! Something my new car would never do.

The following week we got together again and decided that today would be the day. We had all of the parts we needed. We had a full day to work in the shop and make the car run. Tom told me to get a ride to the shop so I could drive the E36 home that night, but his optimism far outweighed mine.

Now that we were sure the car wouldn’t pour fuel everywhere, we decided to prep all the little things for the car to run. We quickly hit a snag while trying to connect the throttle cable, because the four-cylinder throttle cable is longer and has a different bracket than the six-cylinder throttle bracket.

Photograph by Chris Tropea

Of course, we did not think we needed to remove the throttle cable from the rusty car before we scrapped it, so Tom 3D printed a replacement bracket for a temporary “fix.”

The next order of business was the cooling system. I had ordered an aluminum radiator with an electric fan to help keep the car cool, as these older BMWs have fragile plastic systems that always fail. I opened the radiator box and was met with another heartbreak: The fan arrived broken.

Photograph by Chris Tropea

Thankfully it hadn’t damaged the radiator, but we couldn’t install the shroud without the fan. I went ahead and put the cooling system together for now, knowing I would have to take it all apart again to install the fan when it arrived.

Once we put some oil in the engine and double-checked that everything was installed, we tried to fire up the car. The car cranked but did not start.

We weren’t sure why it didn’t start, so we went online to do some research. It turns out we aren’t the first people to have a problem trying to put a BMW engine into a BMW chassis from a different year.

Apparently BMW changed its entire security system electronics multiple times throughout the E36’s run, but thanks to a guide some guy on a forum wrote, we were able to find a specific wire to jump that would solve all of our problems. Except it didn’t. The car did the same thing: crank but not fire.

Time check: 10 p.m.

We checked all of the grounds, looked through the security bypass guide again and even got out the multimeter to make sure things were getting the power they needed. After verifying that everything looked good, we spent a couple more hours unsuccessfully trying to start the car until we finally killed the battery well after the sun had gone down.

We really, really wanted to hear the car run, but Tom made the call that we should go home, get some sleep and come back in the morning to try again.

That was my roughest drive home of the entire project, and I was completely defeated. This was the fifth time I had shown up to the shop expecting to drive the car and the fifth time I had left the shop without getting to drive it.

It wasn’t like we were waiting on a part or forgetting to plug in something or were doing anything wrong. My car just didn’t want to start.

I rolled into the shop early the next morning, not even sure what the plan was for the day. Tom suggested we read the security bypass guide again, which I’m pretty sure we had done the night before, but I figured I would humor him and read it aloud.

Of course, while rereading the guide, we found that we missed a section about cutting a wire in the engine harness, so maybe going home the night before and having a reset wasn’t such a bad idea.

“I’m going to laugh so hard if we just forgot to cut one wire–not like ‘haha’ fun but like ‘haha’ depression,” Tom said before reconnecting the battery and telling me to hop back in the car. I tried to start the car again, and absolutely nothing happened. No crank, no fuel pump, nothing. Did we just kill it?

Photograph by Chris Tropea

Or did Tom just forget to plug back in the engine harness after that cut? Turns out that’s exactly what happened. I glared at Tom through the windshield while he reconnected the engine harness. Then he told me to try again.

I probably wouldn’t believe it if we didn’t have it on video, but the car fired up immediately. Anyone who spends time with me knows that I am never at a loss for words, but a wave of emotions and relief hit me all at once.

For weeks I had been doubting that swapping chassis was the right call as we spent more and more hours trying to make this work, but in an instant all of that went away.

Photograph by Chris Tropea

We spent a few minutes checking fluids and making sure that the wheels were tight (they weren’t) before we were going to take it on its maiden voyage. Tom suggested we hop on the highway real quick to see what it could do, but I told him that a quick drive through the parking lot would be enough for me.

I never went faster than second gear, but at least we made it around the parking lot and could verify that the car could start, steer and stop. And in an instant, I realized that this ordeal was worth it: I’d suffered in the shop for days, but that’s all it took for my E36 to become rust-free and legally registered. Now it’s time to drive it home and get it ready for the $2000 Challenge.

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