We interrupt this program for an e46 repair

I expected more from you, Klaus.

This is supposed to be one piece

All these Mustang parts are rolling in, but I've been chasing down a small vacuum leak in the BMW - it's small but it bugs me. So anyway I was replacing the MAF sensor when I realized that the steering is freaking stiff, stiff like the pump is- done (sonofa...)!  Wife confirmed that it may have occurred as she pulled a fun higher-G turn (no foul, no foul! The car should do it!)

After removing the fan, shroud, and belts, I pulled the power steering pump pulley and shaft right out the front of the housing, spilling ATF all over the driveway. For those of you who aren't intimate with the norms or mechanics here, when the pump comes apart in your hand, that's bad. So up on blocks the e46 went. I removed the bad pump and ordered a new one.

Postmortem

The shaft end was stuck in the pump housing (upper left)

Since I did have the power steering pump out of the car in July when I went through the motor, I just had to know what the hell happened to it. I mean, it was fine. I started the autopsy by removing the pulley and shaft that the pump already fractured and spit out. I disassembled the pump to see what transpired such that the splined end of the shaft broke off.

When I removed the pump cover, milky fluid escaped with a bubbling sigh and let slip the unmistakable burnt metallic scent of catastrophic mechanical failure. The valve body looked surprisingly good, the valves and springs were all lovely, so what gives?

When it comes to making a $200 part into junk, it's usually a 2-cent part that fails.

Pauvre, pauvre, borken pompe.

 Hope the picture to the right is clear enough - here's how it works: the vanes in the pump slide in and out of the hub (in which sat the splined pulley shaft end) when spun outward by centripetal (rotational) force. This drives ATF fluid pressure to the power assist in the steering rack. The vanes themselves are just little square machined bits of aluminum.

Prognosis: And one of those little bastards broke in half, wedged itself between the hub and the housing, and seized the whole damn deal up solid. The engine was still driving the shaft at a zillion RPM via the engine belt and pulley, and the shaft subsequently broke right the hell in half. So now at least I know.

If I had a half decent machine shop and lathe, I think I could rebuild this thing. But I don't, so it's going to become decorative bits on my shop wall.

Hey! Look, the box from OEMBimmerParts just arrived. Time to get this car back out on the road.