In this video, we show you how to change a belt tensioner on a Stihl TS420 disc cutter.

Health & Safety Warning - Please ensure that you have safely prepared the machine and workspace. If you are unsure about any aspect of the task please seek professional advice.

Transcript

Today, we're going to change the belt tensioner on a Stihl TS420 cut off saw. First of all, use a torx spanner to remove the screw that secures the water connector from the underside of the machine. This will provide better access to the recoil. Next, use a 19mm Hex Socket Spanner, turning it anti-clockwise to loosen the tension of the belt. Once this is done, use a 13mm Hex Socket Spanner to loosen the three nuts that secure the recoil assembly. Then revisit each nut and completely remove them, freeing the recoil from the machine. Using the torx spanner, remove the screw that secures the nose guard to the arm. Once the nose guard is off, use the 19mm Hex Socket Spanner, turning it anti-clockwise to further loosen the tension of the belt. Completely remove the front of the saw to free the belt. Use the 19mm Hex Socket Spanner, turning it clock wise to further loosen the tension, to the point where the tension is released. This will make removing the belt tensioner much easier. Then using the torx spanner remove the two screws that secure the clamping lever in place. This part also holds the belt tensioner in position. Once this has been removed you can completely remove the belt tensioner. Place your new belt tensioner into position. Using the torx spanner, secure the clamping lever into place. Once that's done return to tension the belt with the 19mm Hex Socket Spanner turning it anti-clockwise. To fit the belt locate it over the clutch making sure it is sitting in the grooves correctly to prevent damage to the belt. Then feed the belt back through the arm, relocating the arm back in position around the studs. Feed the belt back around the pulley. Slowly turning the pulley will help you easily locate the belt. Make sure the blade turns with a smooth motion. Relocate the casing onto the arm and use the torx spanner to fix this in place. Make sure the screw is secure without overtightening it, as the casing is only plastic. Locate the recoil assembly onto the machine, loosely turn each nut a few times. Then return to tighten each nut with the 13mm spanner, again, be careful not to split the plastic when tightening. Then re-tension of the belt using the 19mm Hex Socket Spanner. Don't forget to fix the water connector back into place under the machine using the torx spanner. That's how you change the belt tensioner on the Stihl TS420. All the parts & tools needed for this task are listed in the description below.

Parts

Parts and tools included in the TS420 disc cutter how-to video.

• Belt Tensioner - 4238 660 0400
• Cast Arm - 4238 701 0202
• Clamping Lever Cover - 4224 664 4200
• Clamping Lever - 4224 664 2100
• Genuine Drive Belt - 9490 000 7901
• Blue Nitrile Disposable Gloves - Varied Sizes
• Genuine Torx Wrench/Plug Spanner - 4224 890 3400
• Non Genuine Torx Wrench/Plug Spanner - 410 250