What is the torque specification for BMW N20 cylinder head bolts?
2 Answers
All bolts of the BMW N20 cylinder head cover should be tightened to a torque of 9.2Nm. To meet the torque requirement: After tightening all the cylinder head cover bolts, re-tighten them again in the same sequence using 9.2Nm to ensure all bolts meet the required 9.2Nm torque specification. Generally, cylinder head bolts require 8-9 kg of torque. Single and double-acting cylinders: Single-acting cylinders have a piston rod on only one end. Compressed air is supplied to one side of the piston to generate pressure, which pushes the piston to extend. The piston returns via spring force or its own weight. Double-acting cylinders: Compressed air is alternately supplied to both sides of the piston, generating force in one or both directions. Diaphragm cylinders: These use a diaphragm instead of a piston and generate force in only one direction, returning via spring force. They offer good sealing performance but have a short stroke. Impact cylinders: This is a new type of component. It converts the pressure energy of compressed gas into the kinetic energy of high-speed piston movement (10-20 m/s) to perform work. Impact cylinders feature an additional middle cover with a nozzle and a drain port.
As a friend who frequently works on car repairs, I've been paying close attention to the data of the BMW N20 engine. Its cylinder head bolt torque has strict standards: first, use a torque wrench to evenly tighten all bolts to 20 Newton meters (Nm) in the diagonal sequence specified in the repair manual to avoid deformation; then, use an angle wrench to tighten an additional 90 degrees to ensure even force distribution across the cylinder head. This is because the engine block expands unevenly under high temperatures, and direct tightening can lead to oil leaks or damage to the gasket. I recommend preparing reliable tools before starting, and torque wrenches should be calibrated regularly. If you lack experience, don't risk DIY—repair costs can double after an engine leak. The BMW N20 is commonly found in the 3 Series or X1, and regular checks can prevent issues. Remember, torque values may vary slightly by model, so it's best to consult the official manual or a professional shop.
