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 MANUALSCHEVROLET1987G 30 VAN V8-305 5.0LREPAIR AND DIAGNOSISENGINE, COOLING AND EXHAUSTCOOLING SYSTEMTESTING AND INSPECTIONCOMPONENT TESTS AND GENERAL DIAGNOSTICS
1987 Chevrolet G 30 Van V8-305 5.0L
Component Tests and General Diagnostics
1987 Chevrolet G 30 Van V8-305 5.0LSECTION Component Tests and General Diagnostics
Cooling System Diagnosis Chart A:
Chart A
Cooling System Diagnosis Chart B:
Chart B
UNCOMMON COOLING SYSTEM PROBLEMS
PROBLEMS NOT REQUIRING DISASSEMBLY OF THE COOLING SYSTEM
1. Locate and remove large external obstructions blocking the radiator or the condenser.
^ Auxiliary oil cooler.
^ License plates.
^ Spare tires.
^ Ice, mud, or snow obstructing the grille.
2. Engine oil is over-filled.
3. Incorrect radiator for the application.
^ Check the part number.
4. Loose, damaged, or missing air seals.
5. Missing or damaged lower air baffle.
6. Incorrect ignition timing.
PROBLEMS REQUIRING DISASSEMBLY OF THE COOLING SYSTEM
1. Incorrect or damaged tan.
2. Worn or damaged emission system components.
^ Damaged PCV valve, TVS or TCS.
^ Malfunctioning emission system components could cause overheating at idle.
3. Pressure-check the cooling system with the pressure cap installed.
^ Shows it the pressure cap leaks because of radiator tiller neck damage.
4. Worn or damaged water pump.
^ Impeller vanes eroded or broken.
^ Worn or damaged bearing and/or seal-check for shaft or bearing play.
5. Plugged radiator tubes.
^ Perform a flow check.
6. Internal system leaks.
^ Head gasket.
^ Cracked block.
^ Timing chain cover.
^ Intake manifold gasket.
7. Plugged coolant passages in the cylinder heads.
^ Visual check.
RENDER: 1.0x
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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.