Mower Deck Idler Pulley AM128118 Compatible with John Deere GT225 GT235 GT245 LT170 X324 GX335 Z245 Z255 Z355 Z425 Z435 Z445 Z465 Z625 Z645 Z655 Z665 LX255 LX266 LX277 LX279 LX288

What It Is

The AM128118 idler pulley is a replacement component for the mower deck’s belt tensioning system on select John Deere lawn tractors and zero-turn mowers. It keeps the drive belt properly tensioned to prevent slipping or premature wear during cutting.

Fitment & Compatibility

Before buying, confirm your deck size and model. This pulley fits John Deere models with 42-, 48-, 54-, and 60-inch decks (including GT225, GT235, GT245, LT170, X324, GX335, Z245, Z255, Z355, Z425, Z435, Z445, Z465, Z625, Z645, Z655, Z665, LX255, LX266, LX277, LX279, LX288). Measure your existing pulley’s outside diameter (typically 3.5 inches) and shaft diameter (usually 5/8 inch). It’s an aftermarket part, so verify it matches OEM AM128118 specs. Check your deck’s belt routing diagram to ensure the pulley’s flange orientation aligns with your belt path.

Key Things to Know

• Quality: Aftermarket, but rated 4.8/5 from 16 reviews—expect good durability for residential use, though not OEM-grade.
• Installation difficulty: Easy (30 minutes). Remove belt, unbolt old pulley (usually a 5/16-inch or 3/8-inch bolt), install new one, re-route belt. No special tools needed.
• Common gotchas: Pulley bearings may be sealed (non-greaseable); if you hear noise after install, check belt tension and pulley alignment. Also, ensure your deck’s spindle bearings aren’t worn—bad bearings can cause premature pulley failure.
• Belt compatibility: Works with John Deere belts like M154660, M157385, or M160667. Double-check your belt’s width (typically 1/2 inch) to match pulley groove.

Should You Buy It

If you need an affordable, reliable replacement for a worn idler pulley on a compatible John Deere lawn tractor or zero-turn, this is a solid choice. It’s easy to install, well-reviewed, and costs a fraction of OEM. Skip it if you require a greaseable pulley for heavy commercial use or prefer OEM parts for warranty reasons.