Mechanical Inspection: Compression

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1998 Mazda Protege, 1998 Mazda Millenia, 1998 Mazda MPV, 1998 Mazda B4000, and 1998 Mazda B3000. However, it is still accessible from the selected car via links, so may be relevant.

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

WARNING: DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking, which can create a fire hazard or contaminate the engine's oiling system.

COMPRESSION SPECIFICATIONS

Application

Minimum psi (kg/cm² ) @ RPM

Standard psi (kg/cm² ) @ RPM

B2500

N/A

⁽¹⁾

B3000 & B4000

N/A

⁽¹⁾

Millenia ⁽²⁾

2.3L

121 (8.5) @ 250

164 (11.5) @ 250

2.5L

132 (9.3) @ 300

189 (13.3) @ 300

MPV

121 (8.5) @ 300

164 (11.5) @ 300

Protege ⁽²⁾

1.5L

146 (10.3) @ 300

195 (13.7) @ 300

1.8L

139 (9.8) @ 300

185 (13.0) @ 300

626 ⁽²⁾

2.0L

119 (8.4) @ 300

171 (12.0) @ 300

2.5L

141 (9.9) @ 250

203 (14.3) @ 250

⁽¹⁾	Lowest compression reading should not be less than 75 percent of highest compression reading.

⁽²⁾	Difference between cylinders should not be more than 28 psi (2.0 kg/cm² ).