GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Timing Gear Assembly

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Unlike the rest of the gasoline engines covered by this manual, the 2.5L engine does not use a timing chain assembly. Instead the camshaft timing gear is directly driven by the crankshaft timing gear. The timing gear (camshaft sprocket) is pressed onto the camshaft and requires the use of an arbor press to remove.

REMOVAL & INSTALLATION



See Figures 1 and 2

The following procedure requires the use of an arbor press, a press plate, the GM gear removal tool No. J-971 or equivalent, and the GM gear installation tool No. J-21474-13, J-21795-1 or equivalent.

  1. Remove the camshaft. For details, please refer to the procedure later in this section.
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  3. Using an arbor press, a press plate and the GM Gear Removal tool No. J-971 or equivalent, press the timing gear from the camshaft.
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When pressing the timing gear from the camshaft, be certain that the position of the press plate does not contact the woodruff key.

  1. To assemble, position the press plate to support the camshaft at the back of the front journal. Place the gear spacer ring and the thrust plate over the end of the camshaft, then install the woodruff key. Press the timing gear onto the camshaft, until it bottoms against the gear spacer ring.
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Fig. Fig. 1: Pressing the timing gear from the camshaft-2.5L engine



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Fig. Fig. 2: Use a feeler gauge to check thrust plate clearance once the gear and thrust plate are assembled to the camshaft

The end clearance of the thrust plate should be 0.0015-0.005 in. (0.038-0.127mm). If less than 0.0015 in. (0.038mm), replace the spacer ring; if more than 0.005 in. (0.127mm), replace the thrust plate.

  1. To complete the installation, align the marks on the timing gears and install the camshaft. For details, please refer to the procedure later in this section.
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