How to Install a SBC Thermostat

Automotive thermostats regulate the engine's temperature by regulating the flow of coolant through the engine and radiator. Like all mechanical devices, thermostats occasionally fail and need to be replaced. The thermostat in the small block Chevy is located in the front of the engine, on top, and is easy to replace.

Step 1 - Drain the cooling system below the level of the thermostat. Place a bucket under the radiator petcock, remove the radiator cap, and open the petcock to drain the radiator. Draining a gallon or so of coolant is usually enough to get the coolant level below the thermostat. Close the petcock.

Step 2 - Remove the upper radiator hose from the thermostat housing. Loosen the hoseclamp with the screwdriver, and twist and pull the hose to remove it. You can leave the other end of the hose attached to the radiator.

Step 3 - Remove the thermostat housing and thermostat. Loosen and remove the two bolts attaching the thermostat housing to the intake manifold. Gentle tap or pry to remove the housing. Remove the thermostat, and scrape the off the old gasket.

Step 4 - Place the new thermostat in your SBC's intake manifold with the pointed end up. Set the new gasket in place, and install the thermostat housing and bolts, using thread sealant on the bolts. Tighten the bolts finger tight, plus one-quarter turn.

Step 5 - Reinstall the upper radiator hose, and tighten the hose clamp.

Refill the radiator, and reinstall the radiator cap. Start the engine and check for leaks.

TIPS: Thermostats come in various temperature ratings. Your auto parts store can help you choose the right one for your SBC. You can reuse your old coolant, but if your coolant is more than five years old, now is a good time to change it.

THINGS YOU'LL NEED: Bucket, Screwdriver, 9/16 wrench or socket, Thermostat and gasket, Gasket scraper or putty knife, Thread sealant

WARNINGS: Be certain the engine is cool before removing the radiator cap. Remove the radiator cap slowly to release any residual pressure. Dispose of antifreeze properly.

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