Noticed start-ups were taking longer than usual so took MINI to an Advance Auto Parts to have them test the battery and starter.

Battery came back as fine. With the starter, the test said the voltage is normal, but the current is low. The tester device advised to check for loose, worn, or corroded wiring.

From what I can tell, just to check the wiring on the starter would require removing everything I would have to remove to replace the starter (exhaust manifold, heat shielding, etc.).

Wondering if others have had similar symptoms and whether it is most likely just the starter failing as opposed to worn/corroded wiring.

 

One thing to add - the problem is definitely worse the longer the car sits. Was out of town for a few days and it started up really slow. It makes me think it's the battery, but the tests have shown otherwise. What would cause a starter to start more slowly the longer it sits unused?

Whatever the case, I've ordered a new starter and will be installing it and cleaning all connections soon...

 

Took a closer look at the test printout from Advance and noticed that the test must be flawed. Said the starter current was 0 Amps. The car would not start if 0 Amps were going to the starter. Will be taking it to a different auto store tonight to have the battery/starter tested again.

All signs seem to be pointing to a bad battery...

 

If the battery is the original one, it needs to be replaced.
MINI's are very demanding about the amount of volts & amperage.
Your battery can check out fine on the test but if it's older than 5 years, it's time to replace it.

 

Not the original in there - replaced it with a Duralast from AutoZone about 6 months ago. Could just be failing early. Good news is its a free replacement if it is. We'll see...

 

The second test came back saying everything was okay - battery, starter, alternator all fine. Since I have a replacement starter already, I'm still going to give putting it in a try anyway.

If the new starter doesn't fix it, I'm thinking it may have something to do with the fuel lines losing pressure over time

Has anyone had something similar happen? Basic symptom is slower startup the longer the car sits unused, with the battery being fine.

 

I think my problem is with the fuel lines (fuel pressure regulator or fuel pump), not the starter. Found this thread which mentions the same symptoms I'm having:

https://www.northamericanmotoring.co...nt-get-it.html

 

did you end up replacing the starter? Tell how you got to it. Was it by removing manifold or taking the air intake box out???

 

Didn't end up replacing it since I pinpointed it as a fuel pressure issue - bad non-return valve in the fuel pump.

However, I did attempt to replace my starter before I figured that out and got as far as removing the exhaust manifold. Couldn't get a good angle on the bolts that attach the starter to the transmission and just ended up putting it all back together without the new starter. Was good in the end, since I returned the new starter (which I didn't need anyway) and got a refund.

If you're going to replace your starter, you'll need to remove the exhaust manifold and the heat shielding. Watch out for the bolts on the exhaust manifold - they tend to rust. I replaced mine. The post-cat bolts that connect to the resonator pipe flange on my MINI were completely rusted - I had to remove the entire exhaust - manifold with resonator/muffler still attached. You may run into the same problem. Also, make sure you get a new manifold gasket and flange gasket (if you're able to unscrew the flange). My manifold gasket was completely shot.

After that the hard part is getting a good angle for the 2 bolts that attach the starter to the transmission. They are on at a high torque, and there isn't much room to move. You'll need an extension, and either a ratcheting breaker bar or metal pipe to put on your ratchet to do it.

Here is the way MINI does it, with torque values:

http://tis.spaghetticoder.org/s/view.pl?1/07/12/34