if ur crank pulley is at tdc (all marks up including cam sproket), will turning it another 360 degrees bring it back to tdc? When changing timing belt, why do people say to turn the crank 3 teeth?

 

One question at a time...

Say the crank starts at TDC, cam is set with valves closed, which means that #1 is at TDC at the top of the COMPRESSION stroke.

Turn the crank 360 degrees and the CRANK will again be at TDC. But the cam arrow is down. So now #1 is at TDC at the top of the exhaust stroke.

Turn another 360deg. & it's back to TDC at the top of compression again. Get it?

When you want to tighten the timing belt, you turn the crank 'a little bit'. The book says 3 teeth because they didn't want to say 'a little bit'. What happens is you're tightening the parts of the belt going up to the camshaft and over to the water pump. Then all the slack moves to the tensioner, which slides over to take up the slack. While you hold a little tension on the crankshaft, you tighten the tensioner bolt to lock the tensioner pulley into place.

 

thanks. That's exactly what I was asking.

When the t belt is off, can the crank pulley, cam spokets be turn clockwise just a little bit to line up the mark? People tell me to only turn it counterclockwise so that's why i'm asking. I think it is ok to turn it clockwise

 

When the crank is at the TDC mark #1 & #4 pistons are at the top. When the crank mark is 180 degrees opposite, then #2 & #3 are at the top. Move the crank mark away from either of these positions so NONE of the pistons are all the way up.

Now you can rotate your camshaft any way you want without having the valves hit the pistons. Put the arrow up and the timing marks lined up right. (whatever that is for your year...)

Now all the valves are closed. You can rotate the crankshaft to the TDC timing mark. Then put on the belt. If you have to move it a little bit that's OK. Don't get carried away moving it a lot.

After the belt is on, you only want to turn it forwards (counterclockwise) because if you turn it backwards it's more likely to skip a tooth.