BMW M328i, Starter Motor Replacement

Ugh, What a terrible place to hide a starter motor. I had to do it though, mine was getting worse and worse.

Yet another issue I wasn’t made aware of when I obtained the car, was that it has an intermittent starting issue, where the starter motor will whirr into life, but not engage the flywheel. This only seems to happen when the engine is hot, and usually it takes a couple of tries and then the solenoid will throw the bendix correctly, and start the engine.

BMW loves to hide critical items, in terrible places. The starter is a good example of this. As something that shouldn’t need to be replaced often, of course it’s going to be hard to get at, and the bolts super tight/seized.

Here it is, hiding at the back of the engine, under where the intake would be

“Oh, that’s not so bad” I hear you say. Well, here are the two retaining bolts.

Oh come on. Why do they have to face the back of the car?!

What isn’t that obvious, is that they are up against the fire wall, so you would need a very specifically angled spanner, of a certain length, to get to them. A straight spanner does not work (I tried. Even purchased a lovely new set of E-Torx spanners for the job. Sigh).

This is what is needed

A 1/2″ ratchet, six extensions, an adaptor, a wobbly, and an E10 E-Torx socket. Don’t try to use a 10mm 12 sided socket on them, or you will be in a world of pain when you strip them.

The main thing that was useful here, is that most of the extensions I used were of the wobbly ended variety, which means they can operate at a slight angle instead of being dead straight. Without this, it would’ve been much harder.

First step is to disconnect the battery, lest you short the starter motor terminals and either run yourself over, or burn the car to the ground.

Now you need to slide under the car, and undo the bolts holding the transmission mount brace on. I didn’t need to support the transmission, the engine stopped it dropping too far, but you will need a small jack to lower it slowly and raise it back up again once done. Also keep in mind that the fan on the front of the engine might get mighty friendly with the radiator; mine was already removed, but keep an eye on that, or remove it.

With the engine and trans tilted back, and the help of your lovely assistant in the engine bay (using handy dandy step ladder), guide massive undoing rod of power up from under the car, onto the bolts and then using your muscles in the limited space, crank that ratchet and crack them bolts. Be damn sure to have your helper make sure the socket doesn’t slip off the bolts though!

My bolts were well seized, and took all my muscles and then some to crack them.

Before removing the bolts, it’d be a good idea to undo the wiring on the solenoid, as this can be tight.

Once they are cracked you can undo them 1/16th of a turn at a time with your fingertips until they finally come out. You will probably swear a lot at this part.

The starter should be free to come out once they have been removed. There is a dowel at the top that the motor sits on, apparently this can seize, but mine was OK. Employ some percussive persuasion if it doesn’t want to play ball.

Once mine was out, I stripped it down to see the dirt packed, rusty mess that it was, and straight into the bin it went.

Now, replacements are damn expensive. A genuine, remanufactured one is about $200NZD plus shipping from your preferred overseas supplier (and they aint light), a brand new one, is about $1100NZD plus shipping. It’s also M3 and Z3M specific.

Being the tight arse I am (or more like, being sick of pouring money into this car), I went with a different alternative. A seller on Trademe, RareElectrical, out of the US of A, sells a lot of starter motors and associated bits. One of their starters that was listed, matches the part number for my starter, and states it will suit an M3 3.0. Its only $157 including shipping. Cheaper than a second-hand one even.

I know it’s not genuine, it’s a knockoff, but the seller has good feedback, so it can’t be all bad. I took a punt and ordered one.

It arrived quick smart, and it looks the part

A quick side by side with the old one shows the solenoid is clocked slightly differently on the new one. This is one thing I had been made aware of, is that a BMW M52 starter (from a 328i for example) will fit and work, but the inlet plenum will contact the solenoid. Well, guess that’s that, this is an M52 starter.

No matter, I can make it work.

Installation is the reverse, except I did the bolts up from the top with a 10mm ratchet. I said a prayer to the car gods, and I managed to not damage the bolts. I would highly recommend copper grease on the bolts, and dowel, before installation, just in case you need to remove it in future.

And the wiring goes on OK.

You can see how far upwards the new solenoid is when compared to the photos of the old one above.

I insulated the main terminal with insulation tape, just as a precaution, but ideally what I have seen done is to ziptie a small flap of rubber over the top of the solenoid. The plenum does come very close to the solenoid, so I used some washers under the mounts on the plenum, to space it up slightly. It gives me about 3-4mm space now, using two washers on each mount. This is enough to easily clear the terminals and not pinch the wires.

Before I put everything back together, I reconnected the battery. No sparks, no smoke and no flames. It’s a win so far.

Turn the key, the starter turns and the engine starts up. Obviously without the intake on I shut it off quickly, but now I know the new starter worked, so back on went the intake.

With it all reassembled, still no sparks, smoke or flames. The new starter sounds very good, it spins so much smoother and quicker than the old one, and with repeated testing, hot or cold, it starts every time the ignition barrel lets it.

Great success, now I just need to fix the ignition barrel.