Almost all tractor starter ring gears are attached to the flywheel by friction from an interference fit. This relies on the tensile strength of the ring gear and the compressive strength of the flywheel. The photograph (below) shows a worn starter ring fitted to the flywheel of a Perkins engine in comparison to a new ring gear (placed on top for comparative purposes only). The newly fitted starter ring is seen (below, bottom) with the leading edge facing towards the engine when the flywheel is re-fastened to the engine.

Replacing the starter ring is a relatively straightforward job which most people can do. The video below shows you how to do this job. Included in the video is:-

• Safely and easily remove the old starting ring without damaging the flywheel.
• Preparing the new ring.
• Fitting the new ring.

After fitting the rings to the piston, liberally oil the piston, piston rings and the inside of the piston ring compressor with engine oil. Ensure that the gaps in the piston rings are positioned in different places around the piston. Lower the connecting rod down the cylinder and sit the piston on top of the block, resting it on two pieces of stiff cardboard or similar material as shown in the picture below. Then place the piston ring compressor over the piston and tighten up, making sure that all of the rings are contained within the compressor.

Remove the pieces of cardboard and with the piston ring compressor held firmly over the cylinder, gently tap the piston into the cylinder with a piece of wood (the shaft of a wooden handled hammer is a suitable object). The piston and its’ compressed rings should slide easily into the cylinder. If the piston jams in any way, stop immediately so as not to damage the rings, withdraw the piston and try again.

When the piston is fitted, the piston ring compressor can be removed and released. Release by pushing the release lever, not by turning the screw in the opposite direction as this will damage it. Always release the compressor after use to prevent damage to the tool.

A piston ring compressor is a relatively inexpensive piece of equipment. We would recommend that anyone refitting pistons to a cylinder should use one of these tools in order to ensure that the piston rings are not damaged in any way.

Read the full instructions for bleeding off the fuel system on a tractor engine.

What people have said…..
1
Guy O’Reilly says:

November 7th, 2008 at 9:20 pm
Thank you very much for your generous display on how to bleed my MF 35. It worked out very well.
I succeeded in closing the lid alone (I could not imagine how you could get two hands in there.) I inserted à loop of nylon (fishing line) in the hole of the small rod to prevent it from shooting out in case it detached from the big spring. When everything was completed, before completely closing the lid I pulled out the nylon line.