If your ***1989 Buick Century***’s starter motor ***spins but the Bendix gear (the part that engages the flywheel) doesn’t pop out***, you're likely facing ***one or more of the following issues***—especially since the starter cables were disconnected when you got the car.
Let’s go step by step:
=== ✅ First: Basic Starter Wiring (for 1982–1996 Buick Century 2.5L & 3.3L engines) ===
Your ***starter motor*** has ***two or three terminals***:
# ***B (Battery terminal)*** — large stud for ***thick cable directly from the battery (+)***
# ***S (Solenoid signal terminal)*** — smaller terminal, gets 12V from the ***ignition switch when you turn the key***
# (Sometimes) ***R terminal*** — not always used; originally sent power to the coil during cranking on older systems
***Correct wiring:***
* ***Thick battery cable (positive)*** from the battery goes to the ***B terminal*** (large post).
* A ***smaller wire (usually purple)*** goes from the ignition switch to the ***S terminal***.
* The ***starter must be grounded*** through its mounting bolts to the engine block.
📌 Make sure the ***ground strap from engine to chassis is intact***!
=== 🔧 Now: Why the starter spins but doesn’t engage (Bendix issue) ===
If your wiring is correct and:
* You hear the ***starter spinning***, but it ***doesn’t crank the engine*** → the ***Bendix gear isn't engaging*** the flywheel.
==== Possible Causes: ====
# ***Low battery voltage***
** 🔋 Starter might spin but solenoid doesn't have enough juice to push the Bendix out.
** ✅ Try jump-starting it or use a multimeter: make sure battery is at ***12.6V+***.
# ***Weak or broken solenoid***
** Solenoid is the part that pushes the Bendix gear out.
** If it clicks or buzzes but doesn't move the gear → it's likely ***bad or sticky***.
** 🔧 Try tapping the starter ***lightly*** with a hammer while someone turns the key.
# ***Incorrect wiring***
** If the small wire is on the wrong terminal, the solenoid might never get signal.
** ✅ Double-check the small wire goes to ***S terminal***.
# ***Bad starter (even if new or rebuilt)***
** If it was sitting for a while or is used, the Bendix can get ***jammed***.
** May need disassembly and cleaning or complete replacement.
=== 🧪 Test trick (if safe to do): ===
* Turn ignition key to ON (not START).
* Use a screwdriver or remote starter to ***short the large post (battery) to the S terminal*** on the starter.
** If the Bendix kicks out and turns engine = ignition circuit may be at fault.
** If it ***still doesn’t engage*** the flywheel = starter itself is likely bad.
=== 🔄 Final checklist ===
Component Check Battery voltage 12.6V+ at rest Starter wiring Big cable to large post, purple wire to S terminal Engine ground strap Tight, clean contact Starter mounting Bolted firmly to engine Solenoid action Clicking and pushing Bendix gear forward Flywheel Not damaged or missing teeth (remove starter to see)