Engine “Hard Parts”: What Are They?

Engine parts such as crankshafts, bearings, pistons, rings, cams, lifters, pushrods, valves, and other valve-train components are called hard parts because they are the hard metal components inside of an engine. They tend to be slow-moving parts because the demand for is relatively low. Engines that need these parts to be repaired are often just replaced with a new or remanned crate engine rather than being overhauled.

Many hard parts are not kept in stock and are instead ordered from a warehouse or distributor as needed. It’s important to let your customers know that some parts may not be available for immediate delivery. Engine hard parts often require a higher level of product knowledge to accurately identify the correct part for a particular application because the part can vary from one model year to the next or even from one model application to the next depending on the powertrain options. You will often need the VIN number as well as the year/make/model/engine size to identify the correct parts for the application.

Something to keep in mind is that a customer who is buying such parts often needs a lot of parts. If  the lower end has worn parts, chances are the engine will need a reground crankshaft with matching rod and main bearings, a new oil pump, timing chain set, oil filter, oil, coolant  and, gaskets. If a customer is working on the top end of an engine, they might need valves, valve springs, valve guide seals, pushrods, and a set of gaskets.

Replacing the rings and bearings also is a more complicated job than just replacing the old parts with new ones. At the very least, the cylinders will have to be deglazed with a hand hone to provide the proper surface to break in the new rings. If the cylinders are worn, they will need to be bored and honed to oversize, and the stock pistons and rings will have to be replaced with the correct oversized parts. Figuring out the correct set of pistons an engine requires can be challenging because of all the different ring sizes and compression ratios.

An engine kit can take a lot of the guess work out of correctly matching the parts while providing the customer with most if not all of the most commonly replaced parts in one box as well as many of the smaller parts that may have been overlooked otherwise.

Valve springs are an often overlooked engine part that should be replaced when over hauling a high mileage engine. Valve springs weaken with accumulated mileage and should be replaced whether or not a new camshaft, lifters, or pushrods are being installed. Weak springs can allow the valves to float or bounce at high rpm causing the engine to misfire or worse.

Exhaust valves are another item that usually needs to be replaced in high mileage engines. Exhaust valves run hundreds of degrees hotter than intake valves and consequently suffer the most wear. If a valve gets too hot, it may burn and lose its ability to seal the combustion chamber causing a pressure leak, misfire, and a loss of power.

One very important item that should always be included in any engine hard parts sale is a tube of engine assembly lube. Protecting wear surfaces such as cam lobes, lifters, and crankshaft journals and bearings with a layer of moly-based lube is critical for the initial break-in when an engine is fired up for the first time.