Remove the Tachometer Drive Assembly on a Case 580CK Tractor With a Diesel Engine

Do you need help with removing the tachometer drive assembly and don't know where to start? This article will teach you how to remove the tachometer drive assembly on a Case 580ck Tractor w/188d Diesel engine and other tractor models.


  1. Locate the tachometer drive assembly. It lays on the right-hand side of the engine between the starter and the power steering pump.
  2. Remove the tachometer cable from the drive assembly in the block. Then clean the area around the assembly. The threads are female fine at about 18 threads per inch. If you do not have the proper specialty tool to remove the assembly, you must then fabricate one from common nuts, bolts, washers, and tubing. To do this, see the drawing and read the description further on.
  3. Screw the specialty tool into the tachometer assembly. Screw as far as possible without over-tightening, secure the bolt head with a wrench and tighten the large nut.
  4. Pull the drive assembly from the engine block. Inspect the drive gear for chips, cracks, or other damage.
  5. Install the new or the serviced drive assembly. Press it back into the engine block using a ¾” socket over the drive assembly and tapping with a brass hammer. Be sure to turn the center gear shaft slightly in either direction after each tap of the brass hammer until you have lined up the teeth of the drive gear with the worm gear on the camshaft. You will know when they are aligned when you turn the center shaft of the drive assembly, and it turns only slightly in either direction, which indicates that the drive gear is resting between the shoulders of the worm gear on the camshaft. You may then tap the drive assembly until it is fully pressed into the engine block.
  6. Reconnect the tachometer cable.

Hand made tool

  1. Gather the materials. To make a removal tool, you will need a grade ‘5’ ¾ - 16NF cap screw 2” long, a ¾ - 16NF nut, a 1-¾”OD washer with a ¾” hole, and a piece of 1-½” ID metal tubing.
  2. Make the tool. Drill a 5/16” hole into the end of the cap screw about ¾” deep. If you do not have a metal washer with a ¾” hole but is at least 1-¾” OD, then you can use a metal file to open the smaller hole to ¾.” Cut a 7/8” section of the 1-½” ID metal tubing and trim the burs. The pieces are assembled in this order: Screw the ¾” - 16NF nut onto the ¾” - 16NF cap screw as far as possible. Place the 1-¾” metal washer on the cap screw. Place the 7/8” x 1-½” ID tubing over the tachometer drive assembly. Thread the cap screw, nut, and washer into the drive assembly as far as possible without over-tightening.
  3. Remove the drive assembly. Hold the cap screw securely with a wrench while turning the ¾” - 16NF nut. As the nut tightens on the metal washer, it presses against the engine block's metal tubing.
  4. Push the drive assembly out of the engine block. Next, turn the 3/4” nut until it pops out of the engine block.


  • On some other models of the Case 580 series of tractors and several other series, in general, a similar drive assembly is used but has external or male threads instead of female threads. A removal tool can easily be made for these as well. First, determine the thread size for that particular drive assembly and do the following. For example, if the external thread is 9/16” -18NF, use a three-inch cap screw of the same size. Place a 9/16 - 18NF nut on the cap screw followed by the metal washer of appropriate size, then a 9/16 - 18NF coupling nut on the threads of the drive assembly. The metal tube will need to be longer by at least ½” to accommodate the extra length of the cap screw and coupling nut. Next, place the metal tube over the drive assembly, followed by the cap screw with nut and washer. Thread the cap screw into the 9/16 - 18NF coupling nut securely. Secure the cap screw with a wrench and tighten the nut on the cap screw. The force of the nut against the washer, tube, and engine block will push the drive assembly out of the engine block.
  • Note: Even if the thread size on the tachometer drive assembly is slightly different from standard SAE NF nuts and bolts, you can still use the closest thread size to get the job done. For example, the drive assembly on my 580ck is about 18 threads per inch at ¾” wide. The closest thread size in SAE NF is 3/4” - 16NF. Although not a perfect fit, it is close enough to catch four or more threads of the drive assembly when tightened snugly. I hope that helps. Have fun.