This 1991 BMW 850i gets much deserved love from its new owner
by Dim Angelov, on May 4, 2021, 12:00
YouTube is full of people creating automotive content. The amount of car content is staggering and ever-increasing, but among the oddest bunch of people on YouTube are the “automotive masochists”. Although not the first one to come to mind (that would probably be Hoovie’s Garage), “M539 Restorations” is a channel focused on the unenviable task of bringing old BMWs back from the dead.
Sreten – the founder of the channel – is an IT guy, but you’d never guess from watching him engaging in this sadistic endeavor. This is actually part four of his “project Marseille” – he names every project after a city and this is the codename of his 1991 BMW 851 E31. He previously got “this glorious turd” running, and now, he’s going to attempt to get it driving.
The first issue Sreten tackles is the clutch pedal, which is “refusing to cooperate”. Essentially, after pressing the clutch pedal, it doesn’t return to its natural position and stays on the floor. He correctly assumes the problem is caused by bad brakeclutch fluid and a shot slave cylinder. “This is what happens when you don’t change your brake fluid for ten years”, he adds. At least, it’s an easy replacement job.
A car that’s been sitting for 10 years needs to have its brake system serviced. The brake fluid can absorb water, which can lead to rust issues and a clogged ABS pump, as explained by Sreten. Luckily, the ABS pump works fine, but new brake lines are still in order for the old 8-series
Next stop – cooling system and timing chain tensioner
Removing the radiator reveals a deteriorated hose and a small radiator leak. Since removing the radiator frees up space, Sreten decides to change the chain tensioner. After that, a new OEM radiator from “Mahle” is being installed.
Sreten decides to check the transmission fluid, which is more of a preventative measure. According to manufacturers, many manual transmission cars have a life-long transmission fluid. However, that doesn’t account for scenarios where a car has not been driven in years.
Cleaning the throttle bodies after 30 years
The BMW 850i has been sitting for 10 years, but some things haven’t been done since it came out of the factory.
“Last time I’ve done this, it made a huge impact on how the car idled”,
Sreten explains. Since there are two throttle bodies, they need synching. This involves driving the car, reaching 5,000 RPM, and letting the car slow down. The process is repeated a couple of times.
There are still some final touches to be done on this BMW 850i, such as addressing a potential manifold gasket leak and the brake pressure regulator. The video ends with a “drive” in the yard of Sreten’s workshop, showing that the car is fully functional and can be enjoyed. Most of the interventions in the video are not very complicated and if you are a DIY guy, this video could be considered a guide of sorts.
It also shows that, back in the day, even a flagship car like this amazing BMW 850i was a relatively simple car, at least compared to more modern equivalents.