Pontiac Fiero 1984-1988 Repair Guide

Piston Rings

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The pistons have three rings (two compression rings and one oil ring). The oil ring consists of two rails and an expander. Pistons do not have oil drain holes behind the rings.

RING TOLERANCES



When installing new rings, ring gap and side clearance should be checked as in the following illustrations. Check the measurements with the specifications in the Piston and Rings chart in the beginning of the section:

Piston Ring and Rail Gap


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Fig. Fig. 1 Insert the piston ring squarely in the cylinder bore and use a feeler gauge to measure ring gap

Each ring and rail gap must be measured with the ring or rail positioned squarely and at the bottom of the ring-travel area of the bore.

Side Clearance


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Fig. Fig. 2 Insert the feeler gauge between the ring and its upper land to measure piston ring side clearance

Each ring must be checked for side clearance in its respective piston groove by inserting a feeler gauge between the ring and its upper land. The piston grooves must be cleaned before checking the ring for side clearance specifications. To check oil ring side clearance, the oil rings must be installed on the piston.

RING INSTALLATION





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Fig. Fig. 3 The piston rings should be installed on the piston as illustrated



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Fig. Fig. 4 Typical piston ring gap locations



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Fig. Fig. 5 Most rings are marked to show which side should face upward

For service ring specifications and detailed installation productions, refer to the instructions furnished with the parts package. If oversized pistons are being used, make sure to select the proper oversize piston rings to fit the oversized pistons.

  1. Using your fingers, install the oil expander.
  2.  

Use care when installing the piston rings so not to scratch the piston skirt.

  1. Install the lower oil control ring and position the gaps as shown in the Piston Ring Gap Location illustration in this section. Install the upper oil control ring.
  2.  

Use a piston ring expander to install the compression rings. Avoid expanding the rings more than necessary, which may cause ring damage.

  1. Using a piston ring installer (expander), install the second compression ring with manufacturers mark facing UP. Install the top compression ring with manufacturers mark facing UP. Position the gaps as shown in the ring gap illustration.
  2.  

 
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