Replacement Deck Belt Tension Spring 539120920 596989801 Fits Sears Craftsman AYP Poulan LSZ5424 RZ4219 RZ4619 RZ5424 Z254 RZ5426 Lawn Mowers (2 Pack)

What It Is

This replacement deck belt tension spring (OEM numbers 539120920 and 596989801) maintains proper tension on the mower deck drive belt, preventing slippage and ensuring consistent blade engagement. It’s designed for zero-turn and lawn tractors from Sears, Craftsman, AYP, and Poulan, including popular models like the LSZ5424, RZ4219, RZ4619, RZ5424, Z254, and RZ5426.

Fitment & Compatibility

Before buying, confirm your mower uses one of these OEM part numbers: 539120920 or 596989801. Check your owner’s manual or the existing spring for these numbers. This 2-pack fits most 42-inch, 46-inch, and 54-inch decks on the models listed, but verify your deck size and model number (e.g., LSZ5424 = 54-inch deck). It’s a direct replacement for the factory spring—aftermarket, but matches OEM specs. Measure the spring’s length (uncompressed) and hook diameter if possible; typical is about 4–5 inches long with 0.5-inch hooks.

Key Things to Know

• Quality: Users report it’s slightly lighter gauge than OEM, but holds tension well for normal residential use. Expect 1–2 seasons of life.
• Installation: Easy—use a spring puller or pliers; no special tools needed. Hook one end to the deck bracket, stretch to the belt idler arm.
• Common gotcha: If your belt is worn or misrouted, a new spring won’t fix slipping. Replace the belt too if it’s cracked or glazed.
• Pack of two: Useful as a spare or for dual-spring decks. Keep one on hand for quick swaps.

Should You Buy It

If you own one of the listed Craftsman or Poulan zero-turns with a worn or broken deck belt spring, this is a cost-effective fix—cheaper than OEM, easy to install, and reliable for light-to-medium mowing. Avoid if you need heavy-duty commercial use or prefer exact OEM gauge.