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.
Engine Cooling Systems: Thermostat
THERMOSTAT REPLACEMENT NOTE: On all six cylinder engines when replacing thermostat, see if rocker cover front bolt boss extends into water passage at thermostat opening causing improper operation. If bolt boss interferes with thermostat, remove just enough of bottom of boss to provide proper clearance.
THERMOSTAT INSTALLATION NOTE: On all six cylinder engines, coolant elbow gasket must be placed on cylinder head before thermostat is installed. Install thermostat with copper pellet (element) toward engine side of passage.
Thermostat is located in water outlet elbow. Test thermostat to see that they start to open at the correct temperatures as indicated in following table.
| Year & Engine | Low Temp. | High Temp. | ||||
|---|---|---|---|---|---|---|
| 1964 | 155-162 | 185-192 | ||||
| 1965 170", 200", 240", 430" | 157-164 | 185-192 | ||||
| 289", 352" | 155-162 | 192-199 | ||||
| 390", 427" | 157-164 | 192-199 | ||||
| 1966-67 170", 200", 430" | 157-164 | 185-192 | ||||
| 240", 390", 427", 462" | 157-164 | 188-195 | ||||
| 289", 352" | 155-162 | 188-195 | ||||
| 1968-73 (All Exc. Pinto) | 157-164 | 188-195 | ||||
| Pinto | 183-190 | |||||
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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.