AM143737 Gen uine Idler Pulley Replaces AM136693 Compatible with John Dee re Z235 Z245 Z255 Z355E Z425 Z435 Z445 Z225

What It Is

The AM143737 idler pulley is a replacement tensioner pulley for the mower deck drive belt system on select John Deere Z-Series zero-turn mowers. It keeps proper belt tension so the blades engage and spin at full speed.

Fitment & Compatibility

Before buying, confirm your mower deck model—this pulley fits Deere Z225, Z235, Z245, Z255, Z355E, Z425, Z435, and Z445 models, but only with 48-inch, 54-inch, or 60-inch decks. Measure your old pulley’s outer diameter (should be roughly 4 inches) and bearing hole size (typically 5/8-inch). This is an aftermarket replacement for OEM parts AM136693 and AM143737. Verify your mower’s serial number range if possible; some early Z425s use a different pulley. If your deck belt is frayed or damaged, replace the belt at the same time.

Key Things to Know

• Quality: Made from stamped steel with a sealed ball bearing. Expect similar lifespan to OEM (2-3 seasons with normal use), but check bearing smoothness before installation—some aftermarket units arrive with slight roughness.
• Installation: Easy—remove the deck belt, unbolt the old pulley (usually a single 5/8-inch bolt), and bolt on the new one. No special tools needed. Torque to 25-30 ft-lbs.
• Gotchas: The pulley’s flange orientation matters—install it with the flanged side facing the belt to prevent belt slippage. Also, if your deck has a spring-loaded tensioner arm, ensure the pulley sits squarely on the arm after tightening.
• Common issue: The bearing seal may weep grease in the first few hours. Wipe off excess; it’s normal and doesn’t affect performance.

Should You Buy It

If you’re a DIY owner of a compatible Z-Series Deere with a 48-60-inch deck and want a low-cost, drop-in replacement for a worn or noisy pulley, this is a solid buy. It’s not a premium OEM part, but for $18.99, it’s a reliable fix that’s easy to install and holds up well for residential use. Avoid it if you need exact OEM spec for a commercial machine or if your deck uses a metric-sized pulley.