One of the more forgotten M cars is the Z4 M Roadster. There was only ever one generation of the Z4 M, and it came in both coupe and convertible form. But despite its uniqueness, it never garnered the same praise or enthusiasm as other M cars of its time, like the E46 M3 and E39 M5. Which always struck me as odd, since the Z4 M has the same brilliant engine as the E46 M3, just in a lighter, prettier package. However, that lack of enthusiast demand has kept prices relatively low, despite the car’s rarity, and that allowed Sreten from M539 Restorations to snag one in Seattle for just $12,000. Of course, it needed some work, but that’s his specialty.
In this new video, you get to see the Z4 M Roadster get a proper engine service, much more than just some spark plugs and an oil change. While his “Project Seattle” ran pretty well as it was, there were certainly some things that needed fixing, like the Vanos unit and cooling system. But Sreten being Sreten, he took it to the extreme and, in his words, made it “bulletproof.”
So in addition to completely rebuilding the Vanos unit, using upgraded parts, and revamping the cooling system, he also replaced the rod bearings and oil pump. The rod bearings are interesting, because his Z4 M is a later model car, which came with updated rod bearings from the factory, as BMW saw issues with early model E46 M3 and Z4 M coupe rod bearings. Despite being the better ones, his car’s still had a ton of wear, especially on the top ones. Many of them were worn down to the copper layer, which is the final wear layer before they fail. And when the fail… big problem. So it’s a good thing he got to them in time. It also goes to show that just because you have a post-LCI S54 engine, that doesn’t mean you can simply forget about your rod bearings. Regardless of mileage, at this age, they should probably be replaced with upgraded ones if they haven’t been already.
When he was done, however, he fixed or refreshed pretty much every fault point of the S54 engine, making it, well, bulletproof. So now he can drive his old Z4 M Roadster as hard as he wants without fear of it blowing up. And when you have a two-door, two-seat roadster with an inline-six that revs past 8,000 rpm, you want to drive it hard. The Z4 M Roadster is one of the coolest cars BMW made this century and this is how they should all be treated.
