Genuine 2001 Nissan Maxima Cylinder Head

2001 Nissan Maxima Cylinder Head Parts Questions & Experts Answers

• Q: How to thorough cleaning and inspect of cylinder heads and valve train components during an engine overhaul on 2001 Nissan Maxima?

  A: Thorough cleaning of the cylinder heads and related valve train components, followed by a detailed inspection, will enable you to decide how much valve service work must be done during the engine overhaul. If the engine was severely overheated, the cylinder heads are probably warped. Scrape all traces of old gasket material and sealing compound off the cylinder head gasket, intake manifold, and exhaust manifold sealing surfaces, being careful not to gouge the cylinder head. Use special gasket removal solvents available at auto parts stores to soften gaskets for easier removal. Remove all built-up scale from the coolant passages and run a stiff wire brush through the various holes to eliminate deposits. Use an appropriate-size tap in each threaded hole to remove corrosion and thread sealant, and if compressed air is available, use it to clear debris. Clean the combustion chambers with a brass wire brush and solvent if carbon has accumulated, then clean the cylinder head with solvent and dry it thoroughly, using compressed air to speed the process. Decarbonizing chemicals may be useful but should be used with caution. Clean the rocker arms and shafts with solvent and dry them thoroughly, ensuring not to mix them up. Clean all valve springs, spring seats, valve stem locks, and retainers with solvent, doing one valve at a time to avoid mixing parts. Scrape off heavy deposits on the valves and use a motorized wire brush to clean the valve heads and stems, ensuring the valves remain separate. Inspect the heads for cracks, evidence of coolant leakage, and other damage, consulting an automotive machine shop if necessary. Check the cylinder head gasket mating surface for warpage using a straightedge and feeler gauge, and if the warpage exceeds specified limits, it can be resurfaced. Examine the valve seats in each combustion chamber for pitting, cracking, or burning, which indicates the need for valve service beyond home mechanic capabilities. Measure the valve stem-to-guide clearance and check for wear; if the measurement exceeds specified limits, the valve guides should be replaced. Carefully inspect each valve face for uneven wear, deformation, cracks, pits, and burned areas, and check the valve stem for scuffing and galling. Measure the margin width on each valve, replacing any with a margin narrower than specified. Check each valve spring for wear and pits, measuring the free length against specifications; any springs that are shorter than specified should not be reused. Stand each spring on a flat surface to check for squareness, replacing any distorted or sagged springs. Inspect spring retainers and valve stem locks for wear and cracks, replacing any questionable parts. Inspect the camshaft bearing journals before sending the cylinder head to the machine shop; if gouged or scored, the cylinder head must be replaced. Any damaged or excessively worn parts must be replaced with new ones, and if the inspection indicates that the valve components are in poor condition and worn beyond specified limits, reassemble the valves in the cylinder head for further service recommendations.