Allowing time to progress without addressing noises heard from the engine compartment could cause damage to other engine components. This is a symptom that may be present at the start of the problem or as the problem progresses and should not be ignored. Those attributed to timing gear failure could be caused by the timing gear itself, the timing chain rubbing or hitting something it shouldn’t, or the timing chain guides being broken or worn out. There are several things that can cause noises from the engine compartment. Rattling noises from the engine compartment may be an indication that the timing gears are going bad or failing. Rattling noises from the engine compartment It is also possible that timing gears that are going bad or failing may cause the engine to run rough, backfire and/or not run at all. If valve timing and ignition timing are not accurate, noises from the engine compartment may be noticeable. If the timing gears are going bad or failing and the timing chains are unable to be turned by the camshaft and crankshaft, valve timing and ignition timing will be off. If the exhaust valves are not opening and closing properly, exhaust gases will be trapped inside the cylinder.
If the intake valves are not opening and closing properly, the correct air/fuel mixture will be unable to enter and remain inside the cylinders. As the piston moves upward inside the exhaust the exhaust valves open to expel exhaust valves from the cylinders. As the piston moves downward inside the cylinder, the intake valves open to allow fuel and air into the cylinder. These components are important for proper engine timing. The camshaft turns to allow intake and exhaust valves on the cylinders to open and close. The crankshaft turns to move pistons up and down inside the cylinders. The purpose of timing gears is to allow the camshaft and crankshaft to turn the timing chain.