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Home >> GMC >> 1983 >> Forward Control 6.2 J, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - Diesel >> Testing >> Injection Nozzle >> Chatter Test
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Chatter Test

NOTE: The sound (chatter) for new and used nozzles may vary. With some used nozzles, the chatter is difficult to detect during slow actuation of the hand test stand lever. Some nozzles may chatter louder than others. As long as there is chatter, the nozzle is acceptable.
  1. Close tester shut off lever at pressure gauge. Slowly depress lever of manual test stand noting whether chatter noises can be heard.
  2. If no chatter is heard, increase speed of lever movement until it reaches a point where the nozzle chatters. At fast lever movement, the nozzle may emit a "hissing" or "squealing" sound rather than the normal chatter. This is acceptable.
  3. These sounds indicate that the nozzle needle moves freely and that the nozzle seat, guide and pintle have no mechanical defects.
  4. Replace any nozzle assembly which does not chatter. Release tester pressure.
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