LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1989 >> Forward Control 3.9 L, Standard >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Cooling System Servicing >> Testing >> Pressure Testing >> Radiator Cap
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Radiator Cap

Visually inspect radiator cap, then dip cap into water and connect to tester. Pump tester to bring pressure to upper limit of cap specification. See Fig 1. If radiator cap fails to hold pressure, replace radiator cap.

Fig 1: Testing Radiator Pressure Cap
G92120Courtesy of GENERAL MOTORS CORP.