HOW IT ALL BEGAN...
It all started when I once bought a Mercedes Sprinter without an engine. I didn't want to install the original OM651. I already knew that people put OM612 and OM613 engines (2.7cdi, 3.2cdi) into Sprinters. I wanted an automatic transmission, but the 5-speed gearbox from the 612-613 engines didn't suit me — it provides a comfortable ride only at around 90-100 km/h (even with a 51:13 final drive), and beyond that, the engine RPM exceeds 2600, making it uncomfortable, although the gearboxes themselves are very reliable. I found a person who had already installed the 7G-tronic automatic. I bought the ECU software and some advice from him — it was expensive, but good things are never cheap. I also bought an adapter plate. It cost me 270 euros with delivery. I installed everything, assembled it, flashed the ECU, and started the engine. Everything was great. The engine had more than enough power. The 7G-tronic transmission worked perfectly, and the cabin was quiet. It was a real pleasure. I drove the car for about a year and then sold it. While the car was on sale, someone noticed the swap and wanted to do the same. I never thought I would be doing swaps, but since the person wanted it... 
Here’s the engine with the transmission already installed in the car.
After some time, a friend of mine also wanted to do the 648+7G swap. And the first thing you need is an adapter. I couldn’t find any good options, so I decided to make the adapter plate myself. I borrowed a caliper and an angle meter from a friend, turned some plugs for the threaded holes and the crankshaft. Then I started measuring and drawing up the design. After three attempts and some refinements, I managed to create something that resembled an adapter plate.
The first adapter plate I made myself.
Everything fit beautifully, and each bolt screwed in without any effort — no need for any adjustments. When installing, it’s important to align the center of the crankshaft properly. I assembled the swap for my friend using my own plate, but there was one issue: there were no guides for the transmission. So far, everything is working fine. He’s been driving it for two years and has covered more than 150,000 kilometers.
I bought myself a tow truck "pomoc drogowa." The vehicle had over 500,000 kilometers on it and came with an OM651 engine and a 7G-tronic automatic transmission. I decided that while the engine was still running, I’d sell it. I wanted to install an OM648 engine with a 7G transmission for myself. I assembled everything on my own adapter plate, but this time I added guides for the transmission. Then I went to the Czech Republic to pick up two more Sprinters. I loaded them up and headed back.
The truck doesn’t really feel the weight of the load, but with such a heavy load, it’s very sensitive to the wind. With a headwind, fuel consumption was around 20 liters per 100 km through the mountains. If I drove at 60-70 km/h, the consumption was noticeably lower.
When I entered Poland, I was cruising at 90 km/h. The vehicle maintained its speed both uphill and downhill, only occasionally shifting gears. The engine temperature climbed to around 105°C during the ascents. I drove like this for 500 km, and with less than 100 km to Wroclaw, I suddenly noticed that the engine rpm started fluctuating while overtaking a truck. The revs dropped from 2000 to 1200 and then stabilized again. I pulled over at the nearest exit, connected the diagnostic tool, and saw error codes related to the transmission: "Incorrect gear or gearbox slipping." The transmission oil temperature was 114°C. I opened the hood — everything seemed fine, but I could smell transmission oil. I started checking the pipes leading to the radiator — everything was dry. Then I looked under the car and saw oil dripping at the junction between the engine and transmission. I managed to drive a couple of kilometers to the nearest rest area and waited for some friends to come pick me up.
The next morning, I started looking for transportation to bring my car to Wroclaw, to my friend’s service. By evening, I had found a transporter. I was waiting for the morning to figure out what had happened. Although, I was 90% sure I already knew the cause. But hope dies last, and I was still hoping that I wouldn’t have to replace the transmission, and that it would just be a seal issue.
The morning came. As expected, the car didn’t fit into the service, so I had to repair it by the gates. After removing the transmission and pulling the torque converter towards me, I felt it snagging on something... I pulled harder, and it came out. And on the bushing of the torque converter, there was a seized, rotated bushing from the transmission oil pump.
My fears were confirmed.
In the photos above, you can see that the center of the transmission was misaligned with the engine! Later, when everything was measured with an accuracy of 0.01mm, I checked the drawings, and the transmission axis was 1.3mm lower than the engine axis. This is according to the drawing!
I had to look for a new transmission, plus oil, gaskets, and filters, as well as a new transmission oil cooler radiator. That’s when I realized that the adapter plate wasn’t accurate enough. From installation to failure, I drove about 2000 kilometers on it. Now, I needed to install the transmission without guides and try to align the axis of the transmission shaft and the engine crankshaft as precisely as possible. To do this, I decided to remove the engine and set it vertically for centering, so that gravity would pull straight down and the transmission could settle into its free position without any interference.
After this incident, it was decided to approach the measurements more responsibly. During the measuring process, differences were found between the 613 and 648 engines, with a discrepancy of 0.136mm.
To date, the adapter plates presented on the website only undergo visual quality control. When the plate is installed on the engine with guides, with the torque converter installed and the bell housing from the 7G-tronic transmission on top, it’s clear that the bushing of the torque converter is centered in the hole of the oil pump. This is noticeable by the uniform edge of the visible part of the bushing.
However, it’s also important to consider that the torque converter is attached to a flexible flywheel, and during engine rotation, under the influence of centrifugal force, it aligns itself!
