Can timing belt cause rough idle?

Yes, a timing belt can cause rough idle. Timing belt controls the opening and closing of engine valves at a precise time interval through various types of mechanisms like cams, gears, linkages, etc.

Engine valve timing affects performance characteristics of an engine like power, torque, fuel efficiency, etc., and if the timing belt is not in good shape or if you don’t keep your timing belt in good shape, then you will face issues like rough idle, engine hesitation on acceleration, etc.

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How a timing belt works

When an engine is running at a certain speed, the crankshaft rotates and thus turns the camshaft which in turn opens and closes valves according to their respective timing at a precise time interval. Now, in an engine with a timing belt installed, the camshaft is rotated by a small gear that is directly connected to the crankshaft on one end and turns the timing belt on the other ends. Therefore it’s important that you keep your timing belt checked periodically for any kind of tears, frays, or cracks and replace it immediately if found any.

For a long time, cars were fitted with timing chains rather than belts . However, as the quality of materials improved with time, the use of timing belts has been on the rise because they are more durable and produce better results in comparison to timing chains.

At present almost all car manufacturers use timing belts in their cars and they are perfect for two-cycle engines (engine with a single moving piston). There is no need for interference from the engine valves during crankshaft rotation. However, these timing belts also have to be maintained properly or else it can cause serious problems in the long run.

What are the symptoms of a bad timing belt?

The most common symptom of a bad timing belt is irregular idle or rough idle, where the engine idles roughly and there are considerable jerks. This happens because the timing belt starts to slip and when this happens, your car will jerk forward while idling even though you aren’t giving any gas.

Another potentially serious problem that can arise due to a bad timing belt is engine hesitation on acceleration.

If your car hesitates while going from a stop to the highway, it could be due to uneven firing of cylinders or improper valve timing and this can lead to serious problems in the long run.

What are the steps to check for a bad timing belt?

You can inspect your timing belt for signs of wear and tear by opening the valve cover.

The crankshaft pulley rotates your timing belt so you have to make sure that it’s in good shape and can rotate smoothly. If not, then there could be problems with the timing belt or it needs to be replaced right away.

If you don’t feel confident enough to check for the condition of your timing belt, you can have it checked by a professional mechanic.

Should I replace my timing belt at regular intervals?

Yes, it is highly recommended that you replace your timing belt on time and keep track of its condition periodically. Failure to do so could lead to catastrophic engine failure which will cost you more in the long run.

In most cases, your car manufacturer provides a recommended replacement timing belt interval for you. Usually, it is safe to replace your timing belt at intervals of 30,000-40,000 miles or every 6-8 years depending upon the make and model of the car. If you are driving under severe conditions like hills, mountains, etc. then you can replace your timing belt after 20,000-30,000 miles.

How can I prevent my timing belt from slipping?

To prevent your car’s timing belt from slipping and causing problems like engine stalling or rough idle, you need to have it check on time and maintain it regularly.

You should avoid revving the engine too much during cold starts, avoid big bumps as these can damage your car’s timing belt, and avoid idling or sitting at traffic signals for long periods of time.

Does timing belt affect RPM?

Does timing belt affect RPM? The simple answer is yes, and the explanation is that your engine works on the principle of four strokes i.e. intake, compression, power, and exhaust. The crankshaft is connected to your car’s pistons through a series of gears that rotate in sync with the crankshaft. It connects the crankshaft with the camshaft which is responsible for opening and closing your car’s valves at the right time.

This timing belt helps keep your engine in perfect sync and ensures that all its parts run smoothly. The system operates like a well-oiled machine but there are many factors that can affect it adversely so you should get it checked right away if you have any problems with your car’s timing belt.

Will a broken timing belt destroy my engine?

Yes, a broken timing belt will totally destroy your car’s engine. The problem is that you don’t know when this will happen and hence it can be catastrophic for your engine.

If the timing belt snaps while the engine is running, then the pistons in your engine will be forced to stop suddenly at different points during their rotation causing the valves to open and close at the wrong time. As a result, the valves of your engine will be severely damaged.

What happens if timing belt is off by one tooth?

If the timing belt is off by one tooth, the pistons will hit valves and head damage will occur. The valves can be bent or destroyed beyond repair. Also, the crankshaft and all connecting rods could get damaged. So, if the timing belt is off by one tooth, do not drive the car. If you have to move it to a safe place for any reason, use a dolly or tow truck.

What happens if timing belt is off by two teeth?

If the timing belt is off by two teeth, the pistons and valves will collide with each other. The piston head can get damaged, as well as many parts of the cylinder block.


If you are experiencing rough idle, engine hesitation on acceleration, or any other performance issues with your car, it is possible that the timing belt has been compromised. Check to see if there’s a tear in the belt and replace it as necessary.


5 Symptoms of a Bad Timing Belt (and Replacement Cost)