Install piston rings

Part 1. Preparation and safety

Objective

• Install the piston rings.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• Many ring sets are correctly sized out of the box, no further adjustment is required.
• Ensure all parts are thoroughly cleaned metal surfaces can be kept from rusting with products like WD 40.

Part 2: Step-by-step instruction

1. Fit new rings in cylinder
   Once the cylinder bores are at their final sizes the new piston rings need to be checked, and if necessary, fitted.
   Many ring sets come out of the box, appropriately sized for the diameter measurement of the cylinder bore.
   The gap in the ring must be at a precise specification when it is installed on the piston and inserted into the bore. To check this, fit a ring into the newly honed cylinder. Use a piston to push the ring to be checked down in the bore. A ring installed in the second groove of the piston acts as a stop so that the ring doesn't get pushed down too far.
2. Measure and adjust ring gap
   Use a feeler gauge to check that the ring gap is at the specification shown in the repair manual. Some types of rings are called "file to fit" or "custom gap" rings. The gap will be too small at first and will need to be filed down until it is the right size. The ring can be filed by hand, one side at a time, moving the file towards the inside of the ring diameter only. Or, you can use a filing machine, which can file both ends of the ring at once.
   A lot of machine shops can do all of this for you. Many of them have powered machines that can do this job very quickly and precisely. Doing it by hand is a tedious process. If you do have custom fit rings, just make sure to keep them in order and label them as they are cut to fit. They'll need to match back to the exact bore that they were filed to fit into.
3. Final clean
   Once all the machining processes are complete, everything needs to be thoroughly cleaned in preparation for the assembly process.
   Hot water and soap do a great job. If you do the final washing yourself, make sure to blow out everything very well with compressed air. Machined and regular metal surfaces can be kept from rusting with regular applications of WD-40. This water displacement fluid forces water out of the pores of metal surfaces and prevents corrosion, and it should be used both on the inside and the outside of your newly machined components.