You may need to replace a busted head gasket for a number of reasons, such as old bolts, dirty bolts or an overheated engine. Whatever the reason, the majority of the upper components near the engine assembly will need to come out of the vehicle. Whether you have a Camry, Avalon, Corolla or Prius, replacing the head gasket follows similar steps, except the cylinder head bolt sequence may differ.
Drain the coolant from your Toyota into a pan positioned underneath the radiator. Unscrew the drain plug on the bottom of the radiator by hand or, if it is too tight, use a pair of pliers to loosen the nut. Disconnect the battery cable from the battery terminal with a wrench.
Drain the motor oil into a drain pan. The oil drain plug is located at the front of the engine compartment and has a large nut. Use a socket wrench to loosen the nut and position the drain pan directly beneath the oil drain plug.
Begin near the upper section of the engine and tag each component before you start to remove and separate them from the vehicle. Disconnect or remove the assemblies, pipes, cables, mounting brackets and bolts. Disconnect or remove the alternator, water filter, air cleaner assembly, exhaust pipe, intake manifold, exhaust manifold, spark plugs, throttle body, camshafts, fuel injectors, timing chain cover, oil control valve and sprockets. You can unlatch the mounting brackets in the vehicle manually. Use a socket wrench to remove the nuts and a wrench to loosen the bolts.
Unscrew the bolts on the cylinder head in a circular pattern, beginning with the ends and moving toward the midpoint of the cylinder head. Dispose of the old cylinder head bolts. Use new bolts when you install the new head gasket. Lift the cylinder head up and out of the Toyota. Examine the cylinder head for nicks, leaks, dents and damage.
Position a new head gasket into the Toyota. The head gasket should sit upright or have the word "Top" on it to assure it is positioned correctly. Thread the cylinder head bolts into position.
Use a torque wrench to torque the bolts to 22 foot-pounds then add a 90-degree pivot. On the third pass, pivot the bolts an extra 90 degrees. Though the tightening sequence may vary, depending on your Toyota, a model with a 1NZ-FE engine has the following top bolt numbers, beginning with the right side: 8, 4, 2, 5 and 9. The lower bolt numbers on the cylinder head, starting from the right side, are 10, 6, 1, 3 and 7.
Replace the upper section of the engine components, including the hoses, wires, assemblies, brackets, anchors, covers and caps. Note the tags you labeled to identify the parts. Replace the coolant and motor oil back into their respective reservoirs. Reconnect the battery to its terminal. Start the engine and check for leaks.
