Flat Idler Pulley Compatible with John Deere Zero Turn Lawn Mower Z425 Z435 Z445 with 48" 54" Deck Replaces AM135526 AM128118 AM143737/AM136693, Idler Deck Pulley

What It Is

This is a flat idler pulley designed to guide and tension the drive belt on John Deere zero-turn mowers. It replaces OEM parts AM135526, AM128118, AM143737, and AM136693, and is intended for 48" and 54" decks on the Z425, Z435, and Z445 models.

Fitment & Compatibility

Before buying, verify your mower’s model and deck size. This pulley fits:

• John Deere zero-turn models: Z425, Z435, Z445
• Deck sizes: 48-inch (48C) and 54-inch (54C) decks only
• OEM part numbers it replaces: AM135526, AM128118, AM143737, AM136693

Critical checks:

• Measure the pulley’s outer diameter (should be ~4.0 inches) and the bearing bore diameter (usually 5/8 inch) to confirm match.
• Inspect the belt routing diagram on your deck; this pulley is typically one of two or three idlers on the deck belt path.
• If your deck uses a different OEM part number (e.g., AM108810 or AM137332), this will not fit.

Key Things to Know

• Quality: Aftermarket replacement, but rated 5.0/5.0. Likely uses a sealed bearing—check for smooth spin before installing.
• Installation difficulty: Moderate. Requires basic tools (socket wrench, possibly a puller if the old pulley is seized). No special skills needed.
• Common gotcha: The pulley may be slightly thicker or thinner than OEM—verify belt clearance to avoid rubbing or misalignment.
• Wear indicator: If your old pulley wobbles or the bearing is rough, replace it immediately to prevent belt damage or deck vibration.

Should You Buy It

Buy this if you own a Z425, Z435, or Z445 with a 48" or 54" deck and need a direct replacement for AM135526, AM128118, AM143737, or AM136693. It’s a solid, affordable aftermarket option for DIY maintenance, but if you prefer OEM or have a different deck size, look elsewhere.