Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSOLDSMOBILE2004BRAVADA AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 778 (ENGINE MECHANICAL (SERVICE INFORMATION))COMPRESSION INSPECTION
2004 Oldsmobile Bravada AWD
Compression Inspection
2004 Oldsmobile Bravada AWDSECTION Compression Inspection
WARNING: This page is about a different car, the 2004 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
WARNING:
- Hot engines and oil can cause severe burns. Be careful not to burn yourself during removal/installation of each component.
- Verify that the battery is fully charged.
- Recharge it if necessary.
- Warm up the engine to the normal operating temperature.
- Stop the engine and allow it to cool down for about 10 min.
- Perform "Fuel Line Safety Procedures". Leave the fuel pump relay removed. (See BEFORE SERVICE PRECAUTION
.)WARNING:
- Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "Fuel Line Safety Procedure". (See FUEL LINE SAFETY PROCEDURE .)
- Remove the plug hole plate. (See PLUG HOLE PLATE REMOVAL/INSTALLATION .)
- Remove the ignition coils. (See IGNITION COIL REMOVAL/INSTALLATION .)
- Remove the spark plugs. (See SPARK PLUG REMOVAL/INSTALLATION .)
- Connect a compression gauge into the spark plug hole.
- Fully depress the accelerator pedal and crank the engine.
- Note down the maximum gauge reading.
- Inspect each cylinder as above.
- If the measured value is less than the limited value, or there is a cylinder whose compression value varies from that of other cylinders by 196.1 kPa {2.0 kgf/cm 2
, 28.5 psi}
or more, add a small amount of engine oil through the spark plug hole. Then measure the compression pressure and perform the respective operations for the following cases:
- If the compression increases, the piston, the piston rings, or cylinder wall may be worn and overhaul is required.
- If the compression stays low, a valve may be stuck or improperly seated and overhaul is required.
- If the compression in adjacent cylinders stays low, the cylinder head gasket may be damaged or the cylinder head distorted and overhaul is required.
Compression
- If the measured value is less than the limited value, or there is a cylinder whose compression value varies from that of other cylinders by 196.1 kPa {2.0 kgf/cm 2
, 28.5 psi}
or more, add a small amount of engine oil through the spark plug hole. Then measure the compression pressure and perform the respective operations for the following cases:
- Disconnect the compression gauge.
- Install the following parts:
- Spark plug. (See SPARK PLUG REMOVAL/INSTALLATION .)
- Ignition coils. (See IGNITION COIL REMOVAL/INSTALLATION .)
- Fuel pump relay. (See BEFORE SERVICE PRECAUTION .)
- Plug hole plate. (See PLUG HOLE PLATE REMOVAL/INSTALLATION .)
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.