Lexus 11101-29405 Cylinder Head Sub-Assembly

Clean and inspect the cylinder head and valve train components to identify necessary valve service work during engine overhaul. Remove old gasket material from the head gasket, intake and exhaust manifold sealing surfaces. Clean scale from coolant passages and remove deposits from various holes with a wire brush. Clean the cylinder head, lifters, valve springs, spring seats, keepers, and retainers with solvent. Remove deposits from the valves with a motorized wire brush. Inspect the head for cracks, coolant leakage, and damage. Check the head gasket surface for warpage and the valve seats in the combustion chambers. Check valve stem-to-guide clearance and deflection. Inspect each valve face for wear, deformation, cracks, pits, and burned areas. Measure each valve's margin width. Check valve springs for wear and measure their free length. Inspect spring retainers and keepers for wear and cracks. Replace any damaged or excessively worn parts. If valve components are worn beyond limits, reassemble the valves in the cylinder head.

Cylinder heads, new or rebuilt, are readily available at dealerships and auto parts stores. Specialized tools and parts needed for disassembly and inspection may make it more cost-effective for home mechanics to buy replacements. Cylinder head disassembly involves removing intake and exhaust valves and related components, assuming lifters or rocker arms and camshaft(s) are already removed. Before removing valves, label and store them for reinstallation in the same valve guides. Use a spring compressor to remove the springs on the first valve and its components. If a valve binds, deburr the area around the keeper groove. Repeat for all valves, keeping parts together for reinstallation. After removal, clean and inspect the head. If overhauling the entire engine, complete engine disassembly before cleaning and inspecting the cylinder head.

After installing the cylinder heads, you should refill the cooling system, change the oil and filter, run the engine, and check for any leaks.