Engine Compression
Check engine compression at cranking speed with engine at normal operating temperature, all glow plugs removed and throttle wide open. Ensure crankcase is full and oil is correct viscosity. Ensure that battery is fully charged. Remove air cleaner (or intake manifold cover). Mark and disconnect injection pump solenoid leads from injection pump. With compression gauge installed, use remote starter to crank engine.
Crank engine at least 5 revolutions, and record highest reading. Repeat procedure for all cylinders using approximately same number of revolutions. Lowest compression reading should not be less than 75 percent of highest compression reading. See COMPRESSION TEST PRESSURE for appropriate readings.
COMPRESSION TEST PRESSURE
| Highest Cylinder psi (kg/cm2 ) | Lowest Cylinder psi (kg/cm2 ) |
|---|---|
| 260 (18.3) | 195 (13.7) |
| 280 (19.7) | 210 (14.8) |
| 300 (21.1) | 225 (15.8) |
| 320 (22.5) | 240 (16.9) |
| 340 (23.9) | 255 (17.9) |
| 360 (25.3) | 270 (19.0) |
| 380 (26.7) | 285 (20.0) |
| 400 (28.1) | 300 (21.1) |
| 420 (29.5) | 315 (22.1) |
| 440 (30.9) | 330 (23.2) |
COMPRESSION RATIO SPECIFICATIONS
| Application | Compression Ratio |
|---|---|
| 7.3L (Diesel) | 21.5:1 |