The new bolts and spring washers finally arrived this week, and last night I got the new vacuum pump put back on, with all hardware intact this time. I started the engine without the belt and fan back in place, just to verify nothing was leaking, and the engine made such a racket I swore there was something gravely wrong with it. Looking back, I think it was mostly just because I was starting the engine in my enclosed garage, with the hood up, and the door open - I think I wasn't used to hearing the engine that clearly. And, of course, it was stone cold, not having been started in days, with the pan full of oil, I'm sure.

Anyway, today I finished the job and reinstalled the new parts: tensioner arm and pulley (with dust covers this time), tensioner spring, serpentine belt, OM606 fan and clutch, and fan shroud. Took her for a shakedown afterward - cold start was again a little noisy, but in no time at all the engine was idling smoothly, making good power, and seemed to be operating more quietly overall - I think some of the racket I attributed to the engine was definitely due to the worn tensioner bearings rattling around. And the engine just sounds better somehow under load - I don't know, maybe the new fan is louder or something? I can't really think of what else has changed that might alter the sound of the motor.

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