Sierra Distributor Rotor 18-5428, OEM 243903, Volvo Penta I/O Ignition, Bosch 4 Cylinder Distributors

The Sierra 18-5428 is a distributor rotor built for Volvo Penta I/O ignition systems using Bosch 4 cylinder distributors. The rotor is the component inside the distributor cap that spins on the distributor shaft and directs the high-voltage spark from the ignition coil to the correct spark plug wire terminal in firing order. A worn, pitted, or cracked rotor causes misfires, hard starting, rough idle, or a no-start condition, so it is a standard wear item to replace along with the distributor cap and points during a tune-up.

This rotor is designed as a direct fit for Bosch 4 cylinder distributors used in Volvo Penta I/O (inboard/outboard) applications, and it corresponds to the original 243903 part number. It is a lightweight, precision-molded component sized to match factory tolerances for correct spark timing and contact alignment inside the distributor cap.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5428
• Product Name: Rotor
• Weight: 0.04 pounds
• Application: I/O - Volvo Penta Ignition System
• Distributor Type: Bosch 4 cylinder

Fitment

• Volvo Penta I/O ignition systems with Bosch 4 cylinder distributors

Replaces (OEM)

• 243903

Frequently Asked Questions

What is the Sierra 18-5428 rotor used for? The Sierra 18-5428 is a distributor rotor that fits inside the distributor cap and directs spark from the ignition coil to each spark plug wire in firing order, used on Volvo Penta I/O ignition systems with Bosch 4 cylinder distributors.

Does the 18-5428 rotor fit Volvo Penta engines? Yes, the 18-5428 rotor is designed for Volvo Penta I/O ignition systems that use a Bosch 4 cylinder distributor.

What OEM part number does the Sierra 18-5428 replace? The Sierra 18-5428 rotor corresponds to OEM part number 243903.

How much does the 18-5428 rotor weigh? The 18-5428 rotor weighs 0.04 pounds.

Will the 18-5428 rotor work with a Delco distributor? No, the 18-5428 rotor is built for Bosch 4 cylinder distributors used in Volvo Penta I/O ignition systems, not Delco distributor applications.

When should a distributor rotor like the 18-5428 be replaced? A distributor rotor should be replaced when it shows pitting, burn marks, or cracking, or as part of a routine ignition tune-up alongside the distributor cap, since a worn rotor causes misfires, rough idle, or hard starting.

Is the 18-5428 a genuine OEM part or an aftermarket replacement? The Sierra 18-5428 is an aftermarket replacement rotor manufactured to match the fit and function of OEM part 243903.

What is included when I order the 18-5428? The 18-5428 order includes one distributor rotor; it does not include the distributor cap, condenser, or other tune-up components.

What is the difference between the 18-5428 rotor and the 18-5402 rotor? The 18-5428 rotor is designed for Bosch 4 cylinder distributors in Volvo Penta I/O ignition systems, while the 18-5402 rotor is a different part designed for Delco EST V-8 distributors.

Can I install the 18-5428 rotor myself? Yes, the 18-5428 rotor is a standard distributor component that installs onto the distributor shaft in place of the old rotor, a task commonly done during routine ignition maintenance.