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 MANUALSCHEVROLET1987S10/T10 P/U 2WD V6-173 2.8LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTTUNE-UP AND ENGINE PERFORMANCE CHECKSCOMPRESSION CHECKTESTING AND INSPECTION
1987 Chevrolet S10/T10 P/U 2WD V6-173 2.8L
Compression Check: Testing and Inspection
1987 Chevrolet S10/T10 P/U 2WD V6-173 2.8LSECTION Testing and Inspection
COMPRESSION CHECK
- Disconnect the primary terminal from the ignition coil.
- Remove all spark plugs.
- Block the throttle plate wide open.
- Make sure the battery is fully charged.
- Starting with the compression gauge at zero, crank the engine through four compression strokes (four "puffs").
- Make the compression check at each cylinder and record each reading.
- If some cylinders have low compression, inject 15 ml (one table spoon, or 3 squirts from a pump type oil can) of engine oil into the combustion chamber through the spark plug hole.
- Minimum compression recorded in any one cylinder should not be less than 70 percent of the highest cylinder, and no cylinder should read less than 690 kPa (100 psi).
Normal Compression: Compression builds up quickly and evenly to specified compression on each cylinder.
Piston Rings Leaking: Compression low on first stroke, tends to build up on following strokes, but does not reach normal. Improves considerably with addition of oil.
Valves Leaking: Low on first stroke. Does not tend to build up on following strokes. Does not improve much with addition of oil.
Head Gasket Leakage: If two adjacent cylinder have lower than normal compression, and injecting oil into cylinders does not increase the compression, the cause may be a head gasket leak between the cylinders.
- Disconnect the primary terminal from the ignition coil.
- Remove all spark plugs.
- Block the throttle plate wide open.
- Make sure the battery is fully charged.
- Starting with the compression gauge at zero, crank the engine through four compression strokes (four "puffs").
- Make the compression check at each cylinder and record each reading.
- If some cylinders have low compression, inject 15 ml (one table spoon, or 3 squirts from a pump type oil can) of engine oil into the combustion chamber through the spark plug hole.
- Minimum compression recorded in any one cylinder should not be less than 70 percent of the highest cylinder, and no cylinder should read less than 690 kPa (100 psi).
Normal Compression: Compression builds up quickly and evenly to specified compression on each cylinder.
Piston Rings Leaking: Compression low on first stroke, tends to build up on following strokes, but does not reach normal. Improves considerably with addition of oil.
Valves Leaking: Low on first stroke. Does not tend to build up on following strokes. Does not improve much with addition of oil.
Head Gasket Leakage: If two adjacent cylinder have lower than normal compression, and injecting oil into cylinders does not increase the compression, the cause may be a head gasket leak between the cylinders.
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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.