BMW Z4 E89 Starter Motor: What Fails, Which Part You Need, and How to Fit It
A single loud click and nothing else when you turn the key is the classic sign of a failing starter on the E89. The complication on this car is that it was built across three distinct engine families — N52, N54 and N20/N55 — and each one uses a different starter, sitting in a different spot. Get the family right before you order parts, because the numbers below are not interchangeable between them.
Symptoms of a failing starter
- A single click, then nothing. The solenoid is engaging but the motor itself isn't turning — usually worn brushes or a pitted solenoid contact.
- Heat-soaked no-start. Starts fine from cold but won't start again straight after a run, once the engine bay has heated up — a classic sign of a starter on its way out, since heat makes worn internals expand just enough to lose contact.
- Intermittent cranking. Sometimes it turns over fine, sometimes it doesn't, with no obvious pattern — worth ruling out a loose battery terminal or earth strap before blaming the starter itself.
- Grinding on engagement. A harsh grinding noise as you turn the key points to the starter's pinion gear not meshing cleanly with the flywheel.
Why this job takes longer than you'd expect
On every E89 engine variant, the starter sits buried underneath the intake manifold, which has to come off to get at it. Budget three to five hours for the job even if you've done starters before on other cars — most of that time is the manifold removal and refit, not the starter itself.
Parts by engine family
Confirm which engine you have before ordering — the badge on the back of the car (20i, 23i, 28i, 30i, 35i, 35is) doesn't always map cleanly to a single engine code across the model's life, so check your V5/logbook or VIN if you're not certain.
| Engine family | Confirmed part number(s) |
|---|---|
| N52 (naturally aspirated, 23i/28i/30i) | 12412354701 or 12412354706 |
| N20 / N55 (turbo, later 28i/35i facelift) | 12417626547, 12417638194, 12417638195 or 12417638197 |
| N54 (twin-turbo, 35i/35is) | Not confirmed — see below |
We could not pin down a single confirmed part number for the N54 specifically. If your car has the N54, take your VIN to a BMW parts counter or a reputable specialist rather than guessing from the N52 or N20/N55 numbers above — they are not a safe substitute.
Torque specifications
| Fastener | Torque |
|---|---|
| N52 starter mounting bolts, upper | 20 Nm + 180° |
| N52 starter mounting bolts, lower | 20 Nm + 90° |
| N20/N55 starter mounting bolt, lower | 38 Nm |
| N20/N55 starter mounting bolt, upper | Not found — use your own manual |
| Intake manifold bolts | 15 Nm |
| Starter positive cable nut | 13 Nm |
A second angle on the manifold removal and starter access, useful if the first video's engine variant isn't quite the same as yours:
Safety first
Disconnect the battery negative terminal before you start — the starter's positive cable is live straight from the battery even with the ignition off, and a dropped spanner across it will do real damage to you and the car. Let the engine bay cool fully if the car's just been driven.
Tools & parts required
- Socket set and ratchet, plus a selection of extensions for the awkward reach under the manifold
- Torque wrench
- New intake manifold gasket(s), if your car's design calls for one
- Replacement starter motor, engine-matched
- Battery disconnect tool or spanner for the negative terminal
Removing the old starter
- Disconnect the battery negative terminal and wait a few minutes before continuing.
- Remove the engine cover, then disconnect the intake ducting and any sensors/connectors in the way of the intake manifold.
- Undo the intake manifold bolts and lift the manifold clear, supporting it so you don't strain any hoses still attached.
- Locate the starter beneath the manifold. Disconnect the positive cable and the solenoid trigger wire, noting their positions.
- Remove the starter mounting bolts and withdraw the starter — it's a tight, fiddly space, so take your time rather than forcing it.
Fitting the new starter
- Offer the new starter into position and fit the mounting bolts, torquing to the figures above for your engine family (or your own manual's figure for the N20/N55 upper bolt).
- Reconnect the positive cable and solenoid wire, torquing the positive cable nut to 13 Nm.
- Refit the intake manifold with a new gasket if applicable, torquing the bolts to 15 Nm in the sequence your manual specifies.
- Reconnect the intake ducting, sensors and engine cover, then reconnect the battery.
Final checks and road test
Start the car several times from cold, checking for any unusual noise on engagement. If you've got access to a diagnostic reader, clear any fault codes that were logged while the starter was failing and confirm none return after a short drive.
Troubleshooting & tips
- Still clicking after the swap. Check the battery terminals and main earth strap for corrosion before assuming the new starter is faulty — a poor earth can mimic starter failure.
- Grinding on engagement persists. Usually means the flywheel's starter ring gear is also worn, not just the starter pinion — worth inspecting before refitting everything.
- Intermittent fault returns. Double-check both cable connections are fully tight; a loose positive cable nut can reproduce an intermittent no-start almost identically.
Getting the engine family right before ordering is the single biggest time-saver on this job. For other Z4 electrical and engine jobs, see our guides to the water pump & thermostat and the convertible roof motor.