Cylinder Head, Intake Manifold, Exhaust Manifold: Inspection

WARNING: This page is about a different car, the 2002 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

Thoroughly clean gasket material from cylinder block and cylinder head mating surfaces. Using a straight edge and feeler gauge, check cylinder head sealing surface for warpage. Check cylinder head intake and exhaust manifold sealing surfaces for warpage. Replace cylinder head if warpage exceeds specification. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.

Check intake and exhaust manifold sealing surfaces for warpage. Replace manifold if warpage exceeds specification. See MANIFOLD WARPAGE SPECIFICATIONS table.

MANIFOLD WARPAGE SPECIFICATIONS

Application	Maximum Warpage - In. (mm)
Exhaust Manifold	.0197 (.500)
Intake Manifold	.0059 (.150)

Using a dye penetrant, check cylinder head sealing surface, and intake and exhaust ports for cracks. If cracked, replace cylinder head. Using outside calipers, measure cylinder head bolt diameter above bolt threads. Replace cylinder head bolt if diameter is less than .3819 in. (9.70 mm).
Inspect cylinder block deck surface for warpage. Replace cylinder block if deck warpage exceeds specification. See CYLINDER BLOCK table under ENGINE SPECIFICATIONS. Inspect camshaft and components. See CAMSHAFT .
Using a valve guide bushing brush and cleaning solvent, clean valve guides. Using an inside caliper gauge, measure inside diameter of valve guides. Using an outside micrometer, measure outside diameter of valve stems. Using the 2 measurements, determine valve guide oil clearance. If clearance is not within specification, replace valve and/or valve guide. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.
Inspect valve lifters for damage. Measure outside diameter of valve lifter and inside diameter of valve lifter bore in cylinder head to determine valve lifter oil clearance. If clearance is not within specification, replace components as necessary. See VALVE LIFTERS table under ENGINE SPECIFICATIONS.