How to Find Top Dead Center: 3 Different Methods

In an engine of a vehicle, the dead center is the position of a piston to the crankshaft. The piston, which is farthest from the crankshaft, is called a top dead center or TDC, and the piston, which is nearest to the crankshaft, is the BDC bottom dead center. In some engines, the TDC can easily be found using the marks, but when these marks get lost or hidden, it becomes somewhat hard to find TDC. That is why we are going to take you through the process of how to find top dead center via different methods.

How To Find Top Dead Center: Three Different Methods

You need to find the engine’s top dead center whenever you work with the engine, like installing a distributor, setting the ignition timing, or any tweak to restore your vehicle’s performance. Let’s see what the different methods are to find the top dead enter-

By Using the Piston Stop Tool                                                    

While working with the engine, regardless of the issue, always disconnect the battery. Keep a flashlight or socket wrench handy to loosen any nut or bolts and see through the dark clearly.

Loosen the nut of the black cable and put it off so it won’t come in contact with the terminals. This way, you won’t get electrocuted while doing how to find top dead center practically.

Go to the cylinder one and disconnect the plug wire. Get the help of the manual of your vehicle to find which spark plug goes into the cylinder one. Once found, grip the spark plug wire where it connects to the spark plug pull it off.

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Use a spark plug socket and a long extension on your wrench to remove the spark plug. Now you can put it aside once you have checked it for any damage.

It is time to use the piston stop tool into cylinder number one. Take the piston stop tool and insert it in the spark plug socket that you removed the spark plug from. Turn it in a clockwise manner to set it there securely.

There are other methods as well, but accessing the top dead center comes very easily with a piston stop tool. Also, make sure you while you are inserting the stop tool into the socket, no dust and debris go in there.

Finding Top Dead Center for More Operations

When you want to access accessories like your power steering and air conditioning, you need to locate the crank pulley that should be near the bottom of the engine. Here you would see a nut at the center of the pulley. Use a wrench counter-clockwise to rotate the motor.

Use appropriate force as larger motors can be difficult to remove than the smaller ones. One thing you should remember is that you do not use the starter to rotate the engine. When the engine is dissembled, it is dangerous to start the ignition.

Keep turning the pulley with the wrench until you come in contact with the piston using the piston stopper tool. Use a marker to mark this location on the harmonic dampener.

When you have made the first mark, rotate the engine back in a clockwise direction. This way, the crank pulley will come into contact with the piston stopper tool once again.

Mark this spot as well on the harmonic dampener. Now you need to measure the distance between these two marks. Divide this distance by two, and this should be your top dead center.

Take off the piston stop tool and put things back in order when you are done making the changes. Reconnect the battery to restore the power of your car, and you are done.

Locating Top Dead Center without a Stopper Tool

Although a stopper tool makes things easy to happen, it is not mandatory to use a stopper when you can find the top dead center without it. It is also advised to follow proper Maintenance Tips so you can keep your car in intact condition.

Here you need to follow the same process to remove the spark plug from cylinder one. But instead of replacing the spark plug hole with the stopper tool, use your thumb while you are there to install the distributor or spark plug wires. However, if the case is about aligning the camshafts, you need to use a stopper tool.

The spark plug can be removed using a spark plug socket, or it will be hard to get it out of the socket. Also, just as previously, do not allow anything to enter the spark plug hole as dust or debris.

Place your thumb over the spark plug hole, and as the engine will rotate, the piston will rise, and you will be able to feel it. Now take your thumb and keep it in the hole of the spark plug in a way that your thumb forms a seal.

Now you need to have someone to rotate the crankshaft with a wrench. Rotate the engine counterclockwise with the wrench and keep rotating until the pressure removes your thumb.

Once you find the pressure, use the flashlight into the hole to detect the top dead center. This way, once you have found the TDC, do the operation for which you accessed TDC and put everything back in order, such as the spark plug.

How to find top dead center
Locate crank pulley to repair air conditioner and power steering (Photo Source: careertrend)


There are many reasons why you should learn how to find top dead center, and the above-mentioned are some of the examples. In case of doubt, you can always take the help of a professional and dig things deeper.

Now while ending up the article here, we hope you understand the three different methods of getting to know the TDC. Wear your safety gear before proceeding with the engine so you can be safe while going on with the process.