What is a Timing Chain and Gear Set?
The timing chain connects the engine camshaft and engine crankshaft, and ensures that they maintain proper timing. Without the timing chain and timing gears that attach to the ends of the crankshaft and camshafts, the engine would not be able to turn synchronously, and would fail. The timing chain may also run other components, depending on the design of the engine. When other components are driven, such as a balance shaft or water pump, they are driven by additional gears.
How does a Timing Chain and Gear Set work?
The timing chain is installed on the engine, behind the timing cover. This chain is much like a thicker version of a bicycle chain, which meshes with the crankshaft timing gear and camshaft timing gear. It is held tight by the timing chain tensioner to ensure the chain is not able to skip a tooth, or 'jump time'. The chain is driven by a gear on the crankshaft, which turns at the speed of the crankshaft at all times. Since the chain is tight, and does not change in length, it turns the camshaft gear(s) in order to open and close the intake and exhaust valves at the right time no matter the speed of the engine.
What are the symptoms of a bad Timing Chain and Gear Set?
If the timing chain fails, the engine will stall immediately. This is because the engine can no longer turn synchronously. This may lead to internal engine damage if the engine does not have valve reliefs built into the engine’s pistons. The check engine light will illuminate on the dashboard in the event of total failure, and OBD trouble codes for misfires, crankshaft position, and camshaft position will be stored. Also, when attempting to start the engine, it may sound different than normal. At worst, metallic clattering noises may be heard in the event mechanical damage.
Can I drive with a bad Timing Chain and Gear Set?
It is not recommended to drive a vehicle suspected of timing component damage. This can quickly result in complete engine failure as described above. If the timing chain has already broken, the engine will not start until the timing chain and gear have been replaced. A rattling or slapping noise from the timing chain that does not stop within seconds of starting the engine requires immediate diagnosis as well.