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.
1978 Plymouth Arrow Base, Automatic TransFACTORY OEM SERVICE PROCEDURE
1977 Models
- With engine coolant temperature below 68°F (20°C), start engine and allow it to idle. Disconnect Red stripe vacuum hose from mixture control valve.
- Place hand under mixture control valve and reconnect vacuum hose. See Fig 2. No suction should be felt. If suction is felt, thermo valve or mixture control vale is defective and should be replaced.
- With engine coolant temperature above 68°F (20°C), disconnect vacuum hose from mixture control valve. Place hand under mixture control valve and reconnect vacuum hose.
- A strong suction should be felt. If no suction is felt, thermo valve or mixture control valve is defective and should be replaced.
Factory Service Tools
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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.
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