The belt tensioner holds the serpentine belt under tension; allowing it to grip the pulleys firmly enough to transmit the engine’s rotating force to the accessories. Most often, the tensioner assembly is secured by either one, two or three bolts, and is fairly easy to remove once the serpentine belt is off. If an engine … Read more
The harmonic balancer is bolted to the front of the engine’s crankshaft. It has two primary parts; the first is a heavy machined inner cast piece and the second is an outer cast piece that drives the serpentine belt. These are joined together with a thick rubber ring. Replacement is fairly simple given the proper … Read more
The valve cover sits at the top of the engine cylinder head; usually it is sealed with a rubber or synthetic gasket that fits into a groove in the metal or plastic cover. The gasket is most often replaced when it begins to leak oil, or as a part of other engine work. The valve … Read more
The thermostat is one of the more important components of an automobile. Think of the cooling system as two parts; the engine assembly and the radiator, with coolant circulating between the two. The thermostat is a valve between the two that closes to allow the engine to heat up to running temperature, and then opens … Read more
The two roles of the alternator are to recharge the vehicle’s battery once it has started the engine, and then to meet all of the electrical demands during vehicle operation. It does this by converting some of the engine’s rotating force into electrical current, taken off through the accessory belt. Signs that an alternator might … Read more
For an engine to run the spark plugs must fire, each at exactly the right moment and reliably. On older engine designs the distributor was an important component in that, taking the high voltage output of a single coil and distributing it to the spark plugs according to the firing order. Two parts of the … Read more
The PCM is the main computer module the vehicle uses to run the engine management systems and control vehicle emissions. The PCM directly controls the fuel injectors and the coils, determining the fuel mixtures and timing based on sensor inputs and it’s basic programming. “PCM” stands for “powertrain control module”, which is used interchangeably with … Read more
An electronic throttle body is basically a cylinder that intake air flows through, with a rotating plate in the middle that can open or close to allow or block airflow. It’s a part of the engine’s air intake system, sitting where the carburetor sat on older design engines. The first throttle bodies were similar in … Read more
If the engine is the heart of a car, the crankshaft is the heart of the engine. It is the primary moving part to which the pistons and connecting rods attach, which drives the transmission on one end and the camshaft and accessories on the other. To replace the crankshaft the transmission has to be … Read more
The camshaft position sensor does pretty much what its name implies – it senses the exact position of the rotating camshaft and it provides that data to the PCM. From there that information is used, along with data from the crankshaft position sensor, to manage ignition and injector timing. In addition to that, on modern … Read more