Hi NAM forumers!

I have a 2005 R53 Mini Cooper S with manual transmission and 136k miles on it.

Recently, I started it, and there was some horrible grinding noise for a second or two, and then nothing, no engine crank etc.

Trying to start again, now there is no grinding noise anymore. Just the clicking of the starter when I turn the ignition key, then nothing, and when I release the key, it sounds like something mechanical is running until it stops about a second later. Listen to it on this video (also attached to this post): https://drive.google.com/file/d/13Az...BL6OORGUi/view

Engine:
As seen on the video, when trying to start the car, the crankshaft pulley moves a few degrees, but then reverses after the starter motor turns off. At the alternator pulley, the belt is basically not moving. Not sure if this indicates the starter is underpowered or there is something seized.

Battery:
After trickle-charging the battery, a batter tester shows 98% charge and 450 CCA, which is a bit low. Also, there's a 0.1 V voltage drop between the terminals in the trunk and the terminals in the engine bay, not sure how relevant that is. The start problem also happens with a battery jump starter (Noco GB40, fully charged) connected to the terminals in the engine bay, so it looks like the battery might not be the issue.

Codes:
The car doesn't show any suspicious OBD codes. The only ones are 00000A "Steering Angle Sensor - LWS, CAN version incorrect" and 000003 "Passenger Seat Occupancy - SBBF, undervoltage", which don't seem relevant.

Mechanically, from what I am reading on the forums, it could be anything: broken or worn starter, broken or worn flywheel teeth, seized engine (for a variety of reasons), seized supercharger, broken alternator, broken A/C compressor. (The supercharger was put in at 111k, the alternator is new as of 119k, and the clutch kit was replaced at 98k, the starter and A/C compressor are original.)

Electrically, I don't fully understand the ignition/immobilizer circuitry, so not sure whether anything there could be out of normal.

Does anybody have suggestions on how to narrow down the problem?

Thank you!

 

Well, you can determine if it's a seized engine or not by putting it in something like 4th gear or higher, then try to manually move the car by pushing at the rear or pulling from the front.

 

Thanks for the tip!

Just to close the loop on this, for future reference. Due to the terrible grinding noise I heard the last time, I decided to proceed very cautiously.

I took the belt off, took the spark plugs out and then hand-cranked the engine (clockwise) using a breaker bar. It turned over easily and smoothly, both with and without clutch depressed. Then I put the spark plugs back in, started the engine (without belt) and let it run for a couple seconds - not longer, since it was running on battery and the water pump was disconnected. Smooth idle. Yay!

Then I hand-turned all the other pulleys. The idler, tensioner, A/C compressor and supercharger pulleys turned fine, but the alternator was seized. Culprit localized!

I took the alternator out (from the top, with just the left side of the modular front end pulled forward, A/C condenser left in place) and disassembled it. The rear bearing was completely shot - one of the ***** dropped out as soon as I opened the alternator.

This Bosch alternator (AL9434X) lasted only 17k miles. RIP. The alternator before that (the original one) latest 119k.

I now ordered a Denso 210-1060 alternator.