Engine parts may be replaced to solve problems such as low compression, low oil pressure, increased oil consumption, engine noise or loss of power, or when an engine is being rebuilt or overhauled. Engine kits include most commonly replaced parts in one box, making it easier to correctly match parts for a particular engine. Gaskets are always needed (head gaskets, pan and cover gaskets, manifold gaskets) and should be included with every engine parts sale.
Oil pumps are a high-wear item and are often replaced to remedy a low oil pressure problem. High-volume oil pumps can improve oil pressure at idle and in engines with increased bearing clearances. Related items that also should be replaced include the oil pickup tube and screen, oil filter, motor oil and pan or timing cover gaskets.
Crankshaft rod and main bearings, and cam bearings may need to be replaced if worn or damaged.
Crankshaft kits usually include new undersized ID bearings to go with the undersize journals on a reground crankshaft. Standard size bearings are required with standard size crankshaft journals. Assembly lube is a must.
New piston rings can restore compression and reduce oil consumption. But if the cylinders are worn, scratched or tapered, they may have to be bored oversize and fitted with new oversize pistons and rings. Piston configurations can vary widely within engine families, so make sure replacement rings are the correct thickness, width and diameter for the application. Piston and ring sets reduce the risk of mismatched parts.
Piston rings may be cast iron, ductile iron or steel, and plain, chrome plated, nitrited or moly faced. Most late-model engines use moly faced rings. Some high-output engines require ductile iron or steel top compression rings for durability. Replacement rings should be the same grade of material or better than the original.
Replacement pistons must have the correct diameter, compression ratio and valve reliefs for the engine, and should be the same or better material than the original (replace cast pistons with cast, hypereutectic or forged, hypereutectic with hypereutectic or forged, and forged with forged only).
Timing belts should be replaced every 60,000 to 100,000 or more miles to reduce the risk of breakage. Timing chains have no recommended service interval but have to be replaced if stretched or broken. Pushrod engine timing chain sets include new crank and cam sprockets, OHC timing chain sets include new chain guides, and timing belt kits may include new idler/tensioner pulleys.
Camshafts and lifters may be replaced due to wear, or to improve performance. Aftermarket cams with various lifts and grind profiles are available. Follow the cam suppliers recommendations for matching a cam to a particular application. New lifters should always be used with flat tappet cams, but are not required for roller cams. New valve springs also are recommended. Use a ZDDP oil additive with flat tappet performance cams to prevent lifter and cam wear.
