I have a 1.5L F55 and need to remove the alternator to get to a leaky water pump, but the alternator is stuck! I removed the two mounting bolts and now it will rotate (around the bottom bolt hole it seems), but it won't actually come off the engine. I came across a post on a different site where someone had the same issue and they said they finally resolved it with a pry bar, so I tried the same thing to no avail. But it does seem like I shifted something because now if I try to replace the mounting bolts, I can't get either one to engage with their threads. So I'm stuck with an alternator that rotates, but doesn't come off and no way to secure it again. Please help!

Here's a video of how it moves: https://photos.app.goo.gl/zcik4NsvyFvimPYs5

 

Might consider removing the intake manifold so you have better access to the rear of the alternator. No promises that it will make a difference, just an idea. It's literally in your way; but who knows, even if you get that access, the alternator may still remain uncooperative.

Intake manifold is held in place with 5 bolts (EDIT, see post 2 below this, ON THE 1.5L it's 4 bolts). Easy removal and reassembly. Obviously there's a bunch of stuff attached to it -- electrical connectors, fuel tank vent valve (perched on top), blah blah. But if one wants to remove it, the only thing that really needs to undo beyond the five bolts and various connectors is its connection to the throttle body and then charged air pipe -- leave the throttle body attached to the intake manifold, and the charged air pipe is easy enough to get detached from the other side of the throttle body to let you remove the intake manifold and the throttle body together.

Again, just an idea. May or may not be helpful. Use *your* best judgment.

 

Thank you cjv2. I almost went down the path of removing the manifold, and actually the only reason I didn't is because my Haynes manual says that there are only 3 bolts at the top of the manifold, but of course it wouldn't come off with those three removed. I moved on because I just wasn't sure it was going to help that much anyway, thought I think it may have given me additional room for prying.

In the end , prying is what it took. After looking at lots of pictures of the alternator and trying to imagine what it might be like at the bottom mounting bolt (and using a mirror to get at least some view of things), I figured the bottom threaded nut insert must fit in a groove on the engine block and that the alternator must need to slide directly toward the front of the car after the mounting bolts are removed. Which is more or less true, but there really is no groove. So if anyone out there ever runs into this issue, it seems, at least for me, that the bottom mount "ears" on the alternator just fit too tightly onto the engine mounting point. I did have to pry, which there is almost no room anywhere to do. But if you do pry make sure that all your forces are working to slide the alternator forward. Don't try to pry it off toward the passenger wheel well until it's actually free at the bottom mount at which point it should be ready to just lift away. I've attached some pictures, which just show what it all looks like with the alternator removed.

I also had to remove the valvetronic servomotor to squeeze the alternator out of the engine bay. Haynes has instructions for removing the valvetronic motor, but they don't mention that it needs to be done in the section on removing the alternator. That's what the oil you can see in the first picture is from.

 

Nice work -- I see the notch you're talking about down low for the alternator bolt. Quite the non-intuitive setup to be sure.

FYI BMW TIS does mention removing the servomotor as prerequisite to getting the alternator out. But in re the alternator itself, all it says is to remove the top and bottom mounting bolts and "feed out alternator." Maybe if you take that literally and give it cookies or french fries it comes out more easily, I dunno. Yeah, prying would be the only way.

May interest you to know that I had it wrong -- but so does Haynes from your description -- for the number of bolts on the intake manifold (or "intake plenum" as BMW TIS calls it) for a 1.5L F55 (base Cooper). Not 5 bolts, and not 3 bolts.

The 2.0L engines have 4 cylinders and 5 bolts. In the case of the 1.5L, it's 3 cylinders and 4 bolts. Here ya go.