Timing chains have a longer life span than belts, however, they also have more failure points. Additionally, chains sit within a timing chain cover whereas the belts are usually open in the engine bay. Timing belts are made of rubber and do not run against sprockets. timing beltsĪt the simplest level, timing chains are made of metal and turn on gears or sprockets. When the guides fail, the chain gets off track and can jump teeth or completely fall off. The guides are usually manufactured of plastic which means they easily break over time from heat, engine vibration, etc. When oil levels get low the oil pressure drops and therefore the tensioner doesn’t have the pressure it needs to keep the slack out of the line.
The tensioners use oil pressure to keep tension on the chain. Hydraulically actuated tensioners are known to fail due to low oil levels or oil pressure leaks. When oil levels get too low the chain can be starved of lubrication which also causes it to stretch. Since the metal chain runs on metal gears, it creates heat and friction when not properly lubricated. At the chain stretches, it becomes loose on the gears and can then “jump teeth” or even completely fall off of the sprockets.Īdditionally, timing chain stretch can be caused by low oil levels. Over time the heat causes the metal chain to slowly begin to stretch. Because the timing chain sits right near the block it is subject to lots of heat. The primary cause of timing chain failure is timing chain stretch. Most tensioners are spring-based and hydraulically actuated, meaning they use oil pressure to keep the chain tight. The timing chain tensioner makes sure there is no slack in the chain. The last important piece to timing chains is a tensioner. Therefore, the timing chain sits within a timing chain cover, which bolts up to the block and protects the timing chain from road dirt and debris while also lubricating it with engine oil.Īdditionally, the timing chain also has timing chain guides, which help keep it on track and prevent it from slipping off of the sprockets. The timing chain is made of metal and turns on metal gears or sprockets, so it needs to be lubricated with oil. Here is an example of a timing chain system with the chain, guides, tensioners, sprockets, etc. As the camshaft turns, small lobes also called cams push up against the valves to open them. The camshaft turns once for every two turns of the crankshaft. The timing chain is connected to the camshaft and crankshaft by a set of gears, usually located on the front of the engine block. What is a timing chain?Ī timing chain is responsible for opening and closing the intake and exhaust valves in an engine.
#BAD TIMING HOW TO#
This article will go into detail on timing chain function and how to tell when your timing chain starts to fail. Over time they wear down and stretch which can lead to various performance issues and even cause catastrophic engine damage. The timing chain is responsible for ensuring proper timing of the valves opening and closing. Next, the spark plugs fire creating combustion, sending the piston back downwards where the exhaust valve opens letting the air out of the cylinder.įor engines to function properly, the timing of the intake valve opening/closing, the combustion taking place, and the exhaust valve opening/closing must be precise. The piston pushes back upwards, compressing the air and fuel and the intake valve closes. The piston pushes downwards and the intake valve opens, letting air and fuel into the cylinder. The first “stroke” in a typical four-stroke engine is the opening of the intake valve.
Timing chains are an essential component to engine timing.
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