Timing belt removal instructions and TDC explanation

[Mux213]

To start with you'll need some tools.
- a good wrench set. If I am not mistaken you need a 19mm 14mm and 10mm socket
- a braker bar (or pipe to extent your wrench)
- a new spanner, always replace the spanner when you replace your timing belt
- a new timing belt
- a pulley puller.

When replacing the timing belt there is one thing you really need to know, and that is everything about timing. If you get the timing belt off by even a notch your engine will not run fluently. You first need to learn how to identify how to put your engine in the right position so you can use the timing marks to align everything.

The timing marks on your engine are aligned to when your engine is at Top Dead Center (TDC). TDC is reached when the #1 piston is at its top most position during the compression stroke. Each piston reaches its top at 2 points, after compression (right before the fuel is ignited) and after the exhaust stroke (to push the burned gasses out of the cylinder). This is important to realize since there are 2 times where the #1 piston is at its top position, you must make sure you always align to the compression stroke, not the exhaust stroke.

Recognizing when the #1 piston is at its topmost position is very easy. When the front pulley is still on you simply look at the timing indicator. On the pulley there is a mark that will align up with the 0 degrees mark:

Once the pulley is off you can still see a mark on the crank shaft that lines up with another mark on the cover:

Last but not least, when the cover is off, there is another mark behind that that lines up with the mark on the crank shaft. I don't have a picture of this I'm afraid but you will recognize it immediately when you get the pulley off.
Now I can't stress this enough, these marks line up in 2 situations, at compression and at the exhaust stroke. You need to make sure you have the compression stroke. There are two ways of doing this. First and easiest is to look at the alignment of the camshaft sprockets, we'll get to that in a minute. You can only use that method when you still have your old timing belt on.

The other is to look at your distributor. We didn't have to do this as we kept everything in alignment during the whole procedure so no pictures, but basically when you take the distributor cap off the rotor inside should be (almost) in contact with the #1 sparkplug wire on the compression stroke and it should be in contact with nothing on the exhaust stroke. You only need a spark after compression afterall

What we did however was simply look at the camshaft sprockets:

As you can see in the picture there are 2 small marks on the backplate and there is a small indent on each sprocket that line up. They line up exactly on the compression stroke of the #1 piston, and they will be opposite from the marks at the exhaust stroke. The situation in the picture shows TDC which is what you want!

To get your engine in TDC is fairly simple. Put your car in neutral, put a 19mm socket and place it on the bolt of the crankshaft pulley. Now turn the engine clockwise until you reach TDC. During this procedure you will go through all the compression strokes of the 4 pistons which can be hard, but I found turning it this way works fine. You can also turn your engine using your starter or once the pulley is off, you can try to turn it by pulling on the timing belt or by moving the camshaft sprockets. These last 2 methods however are only recommended for small changes.

During the procedure of changing your timing belt you will do things that will change the position of your crankshaft. It is smart to always bring it back to TDC. Once your timing belt is off you really need to make sure your crankshaft is at TDC and not at the exhaust stroke when you put your new timing belt on.