Vauxhall Astra Alternator: Specs, Fitment & Common Faults
A genuine, documented parts-manufacturer finding: a missing protective cap on the free-wheeling clutch causes premature bearing failure — with a specific replacement part number.
Illustration for editorial purposes
Opens live listings in a new tab.
OEM Part Number: 13588306 (genuine alternator — confirm via VIN) — aftermarket alternators Bosch 1 986 A01 511 / Valeo 444476
| Alternators (aftermarket) | Bosch 1 986 A01 511 (130 A, freewheel pulley, 5 ribs, 54 mm, new, plug 180, excludes vacuum pump, 168 mm length); Valeo 444476 (140 A, rigid V-ribbed pulley, 6 ribs, 54 mm, remanufactured exchange, clamp F/L, core charge £50.79); Denso DAN1331 (140 A, rigid multi-rib pulley, 6 ribs, 54 mm, new, OE quality); AS-PL A0781S (145 A, freewheel pulley, 5 ribs, 54 mm, new, plug PL_2201); AS-PL A0863S (130 A, rigid belt pulley, 5 ribs, 54 mm, new, plug PL_2201); Ridex 4G1452 (140 A, rigid multi-rib pulley, 6 ribs, 54 mm, new, integrated regulator, excludes vacuum pump); BV PSH 135.970.170.500 (170 A, freewheel pulley, 5 ribs, 54 mm, new, Valeo-new quality). |
|---|---|
| Outputs & variants | Five outputs appear: 130 A, 140 A, 145 A, 150 A and 170 A. The 130 A and 145 A units are five-rib on a 54 mm pulley (Bosch, AS-PL, BV PSH); the 140 A and 150 A units are six-rib (Valeo, Denso, Ridex, Walker); the 170 A units appear in both five-rib (BV PSH 135.970.170.500) and four-rib 57 mm form (BV PSH 135.901.170.500). Both freewheel and rigid pulleys are listed, with Walker WAL00821 explicitly supplied without freewheel. |
| Genuine (OE) numbers quoted | AS-PL A0863S for OE 0126312100; AS-PL A0781S for OE 0126312147. |
| Fitment notes | Only the Bosch and Ridex entries state they exclude the vacuum pump, which matters on CDTi diesels. The Valeo exchange unit carries a £50.79 core charge and Walker units £25.12 to £50.24, refunded on return of the old alternator. |
A Genuine, Documented Cause: A Missing Protective Cap on the Free-Wheeling Clutch — Vauxhall Astra Alternator
On the Astra H specifically, parts manufacturer HELLA has documented a genuine, specific cause of premature alternator bearing failure: a missing or faulty protective cap on the belt pulley's free-wheeling clutch. Without this cap in place, the bearing is exposed to dirt and moisture it isn't designed to tolerate, wearing out considerably faster than it should and producing a whining or grinding noise that gets progressively worse. This is worth checking specifically if you're replacing an alternator or buying a used/reconditioned unit — the protective cap (available separately under part number 93167817) needs to be present and correctly fitted, since its absence is a documented, specific cause of the exact failure you'd otherwise be trying to fix.
Vauxhall Astra Alternator: Often Blamed on the Battery Instead
On the Vauxhall Astra, a failing alternator and a simply weak battery share almost the same symptom set at first: dim lights, sluggish starts, charge that won't hold. Mixing the two up is common, which is why plenty of people replace the battery only to find themselves back at the garage shortly after.
Vauxhall Astra Alternator: Watch: Replacing It
Astra K 1.4 turbo petrol
Vauxhall Astra Alternator: What It Does
The Vauxhall Astra's electrical systems and battery charging both depend on the alternator generating electricity whenever the engine runs. If it's healthy, the battery's job shrinks down to starting the engine and handling brief surges in demand, not powering everything else on its own.
Opens live listings in a new tab.
Vauxhall Astra Alternator: Warning Signs, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Alternator Guide for symptoms to watch for (plus a genuinely useful two-minute test to confirm it's not the battery instead), confirming the right amperage and fitment against your VIN, and which brands are worth trusting.
More Vauxhall Alternator
The same part, covered across other Vauxhall models.