50-99418A2 Aftermarket Mercruiser/Volvo Penta GM 305 5.0L Starter Motor (1976-95) | Sawley's Select Marine Parts

🔧 Product Description

Aftermarket replacement GM V6/V8 Delco 10MT Marine Starter Motor - Replaces Part Number: 50-99418A2

New aftermarket original-style Delco 10MT high-torque marine starter replacing MerCruiser 50-99418A2. It uses a 12-volt, 9-tooth clockwise drive and the staggered two-long-bolt mounting pattern for GM engines with a 14-inch flywheel.

⚙️ Key Features

• 12-volt electrical system

• Clockwise rotation viewed from the drive end

• 9-tooth original-style starter pinion

• Delco 10MT high-torque direct-drive construction

• Two long mounting bolts in a staggered/offset pattern

• Designed for a 14-inch GM flywheel

• Marine ignition-protected construction

• Complete new starter motor with integrated solenoid

• Marine or engine-grade corrosion-resistant construction

• Direct replacement only after voltage, rotation, tooth count and mounting pattern are confirmed

🧰 Kit / Assembly Contents

• 1 × Complete starter motor assembly - P/N 50-99418A2

• 1 × Integrated starter solenoid and shift mechanism

• 1 × Installed pinion gear and overrunning clutch/Bendix assembly

• 1 × Installed armature, brush holder, field-magnet/winding and drive housing

• Mounting bolts, battery cables, relays and external wiring are transferred or renewed separately unless supplied

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 50-99418A2 → Cross-references MerCruiser 50-12121A2, 50-12177A2, 50-77328A1, 50-77328A3, 50-806964A2/A3/A4, 50-812428A3 and 50-812604A2

• Modern PMGR replacements such as ARCO 30433/30470-A and later Mercury 50-863007A1 can use an 11-tooth pinion while replacing the original 9-tooth 10MT starter

OEM / Related Numbers:

• 50-99418A2

• 50-12121A2

• 50-12177A2

• 50-77328A1

• 50-77328A3

• 50-806964A2

• 50-806964A3

• 50-806964A4

• 50-812428A3

• 50-812604A2

• OMC 984456

• OMC 986505

• Volvo Penta 3850525

• 3853982

• 3854751

• 3855177

• 3856004

• 3860764

• Delco 9000735

• 9000819

• 9000840

Aftermarket / Verified Equivalents:

• Sierra: 18-5910 original-style 10MT family

• ARCO: 30433 PMGR replacement

• ARCO: 30470-A 1.7kW PMGR replacement

• API/Protorque marine GM starter family

• Recmar: REC50-99418A2

🚤 Compatibility

Commonly used on:

• MerCruiser, Volvo Penta, OMC, PCM and other GM-block marine petrol starting systems

Typically suits:

• Engine / Component models:

• MerCruiser GM 4.3L V6 and 5.0L/5.7L V8 applications using the staggered 14-inch-flywheel starter

• MerCruiser 7.4L and 8.2L GM V8 applications whose parts catalogue specifies 50-99418A2

• Volvo Penta and OMC GM V6/V8 marine engines using the equivalent 3850xxx/3860764 starter family

• PCM, Indmar and Marine Power GM engines using the same two-bolt staggered starter pattern

• HP Range: Engine-rating dependent

• Year Range: Principally mid-1970s through mid-1990s for the original 10MT application; later PMGR replacements cover additional years

• Component Identification: Confirm 12V, clockwise rotation, 14-inch flywheel and staggered two-long-bolt mounting. Original 10MT is 9-tooth; a correctly designed PMGR replacement may use 11 teeth.

🔌 Function

The starter motor converts battery electrical energy into high-torque mechanical rotation to crank the engine. When the start circuit energises the solenoid, the pinion moves into the flywheel ring gear and the motor turns the crankshaft until combustion begins. The overrunning clutch then protects the starter as engine speed rises.

Common signs of failure / service requirement:

• No-crank condition even though the battery and start-control circuit test correctly

• Solenoid clicks but the starter motor does not rotate

• Starter turns slowly, draws excessive current or overheats the battery cables

• Pinion spins without engaging the flywheel ring gear

• Grinding, clashing or repeated pinion kick-out during cranking

• Intermittent cranking caused by worn brushes, solenoid contacts or heat soak

• Corrosion, water intrusion, burnt windings or excessive shaft/bearing play

📦 Condition

• New aftermarket replacement starter motor

• Brand new

• Supplied in original or equivalent packaging