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How to Torque Head Bolts

Head bolts hold the cylinder head to the engine block while maintaining a strong leak-free head gasket seal. The head bolts must be able to withstand the strong forces exerted by the internal combustion process. Torquing down the head bolts at the correct specifications and in the correct sequence is extremely important; otherwise, the cylinder head can separate from the block and cause serious damage to the engine.

Instructions

1

Consult your engines service manual for the correct torque values for the head bolts. The service manual should also specify the correct sequence in which to torque the head bolts.

2

Inspect the head bolts, and ensure they are clean and undamaged. Bolts with damaged threads, misshapen bolts and worn bolts can reduce the clamping force needed to hold the cylinder head down, as well as cause the torque wrench to give false readings. Use new head bolts whenever possible. Do not reuse torque-to-yield bolts.

3

Apply a small amount of lubricant to the threads on the head bolts. You can use a variety of lubricants, including Teflon-, wax- and graphite-based lubricants. Do not use thread lubricants on torque-to-yield bolts.

4

Tighten the head bolts to the correct specification with a torque wrench. Torque the bolts in the correct sequence as specified in the service manual.

5

If the cylinder head requires retorquing, start the engine and let it run until it warms up to normal operating temperature, then turn it off. Retorque each bolt in the specified sequence to the required specification.

Posted by Unknown at 3:30 AM

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Labels: bolts, head, how, to, torque