Hi,

I have an '04 SXT and am getting ready to replace the timing belt this weekend. I have studied the whole procedure in the Chilton manual and feel confident and ready, aside from one remaining question. There are steps in the manual before placing the new belt on the pulleys that say to start with the crankshaft timing marks aligned, then back it off to three notches before TDC, then to advance it again to 1/2 notch before TDC. What is the purpose for this back and forth action of the crankshaft? Thanks for any insight.

Justin

 

well i just replaced my timing belt last week "mine broke" so i had to get it alined back up, but why i figured they had you do this was cause its almost impossible to get the lines to stay perfectly lined up "guessing cause its on the compression stroke" not a hundred percent sure, plus the belt teeth dont line up if its dead center on, like i said im not a hundred percent sure why but make sure you do it anyways, i did what the chilton said word by word "also found a awesome youtube video that gave me good advice on how to do some stuff" another thing is make sure you have all the right tools, there is a few special tools you will need like a t-55 hex bit and a hermonic puller.... good luck.

 

I finished up my timing belt in a long day in the garage yesterday, and have a little insight into my own question now. In order for the timing belt to line up properly when tensioned, the crankshaft pulley must be 1/2 tooth before TDC. I think the reason to take it 3 teeth before TDC and then advance it to only 1/2 a tooth is that there is some play in the crankshaft/rods/etc. and doing this ensures that all that "slop" is out and both pulleys are truly where they should be in relation to the parts they drive.

A few extra tips I found to work great:

The engine does have to be repeatedly raised and lowered to remove various bolts. A transmission jack with a big saddle that fits the oil pan was priceless here. I found it much easier/safer than a floor jack.

In order to change out the water pump while you're in there, the camshaft pulley must come off to remove the back timing belt cover. I had to use a chain wrench to hold this pulley. I found it helpful to cut out a piece of dense foam from a cheap camping pad and wrap this around the circumference of the pulley in order to protect the teeth.

Thanks chronoboy for the tip on the T-55 Torx bit, I didn't have one on hand.

The car seems to run great, I did the job in my dad's shop 90 miles from where I live and drove it home afterward. I had heard sometimes the camshaft/crankshaft position sensors need to be reset with a scanner but so far my car seems to run just like before I did anything.

-Justin