I know there are hundred timing belt threads out there but I haven't seen this question answered. I am installing a new timing belt (first timer) and I get everything lined up perfectly but after two revolutions the crank is off by one tooth. I have done this three times with the same result. I am not having much trouble getting the belt on as I have either loosened the timing belt tensioner or removing the top center idle pulley, or both. So I don't think anything shifts while putting the belt on because it still looks good once it is on. I tighten the tensioner bolts and obviously install the pulley before manually turning the crank but I have not pulled the pin on the tensioner. So my question is this: Is the belt skipping a tooth while I turn the crank because I have not released the tensioner OR do I need to slightly adjust one or both cams a bit to get it to where the crank will line up after a rotation? It would seem to me if you are lined up perfectly upon install there is no way short of skipping a tooth it should become misaligned after a rotation. Appreciate any guidance.

 

Perfectly normal. Stopped me in my tracks a few years ago as well. If your marks are correct when you install the belt, carry on.



Andreas

 

If you're talking about the hard mark on the crank I believe it should line up after you rotate.

If you're talking about the installation marks on the belt itself they won't line up after you rotate.
They are just there to help get the belt on.

 

/\ /\ /\ Alignment marks are fleeting, once rotated they are gone. But the hard marks on the crank and cams do need to line up every two rotations of the crank, or something is off. If you didn't have the marks on the belt, that's what you'd have to use. The marks are just a touch easier to use because you don't need to worry about where the slack is in the belt before you pull the pin on the tensioner.

I was recently doing a timing belt on a very closely related engine (3.0 V6 in a Highlander) and I was stumped for a little bit. I kept lining up the belt via the stripes, it would look 'pretty good' (I know it will be off a little when the belt is slack, before the tensioner takes up all the slack). Then I'd pull the pin, rotate the crank around two turns... and one of the cams would be off by about one tooth's worth. I did this *TWICE* before finally realizing I was putting the belt on 'backward' (partly due to the sideways orientation of the engine throwing me off??? or just derpy mechanicking?). Anyhow, took the belt out, flipped it around, used the lines again, and *bingo* everything was lined up correctly after rotating it around twice.

And I would not be trying to rotate the motor with the tensioner pinned/belt slack. It's pretty much just asking for something to slip somewhere while doing that. Line it up via the marks, pull the pin, rotate the crank around twice, double check the hard marks. It's a PITA to recompress the tensioner if you get it wrong, but that's the breaks. Just take it slow, the hydraulic damper in the tensioner does NOT like to be hurried, and can and will break something if forced too hard.

 

I finally did get this. I am not sure what was causing the timing mark on the crank (I did not mean the belt marks, I knew they would not line up again ) to go off but there were a few things I changed all at once on the last attempt where it worked:

1) I installed the belt in a different order as per some other forum posts I saw...basically going left cam pulley first then working my way to the crank and then installing the center idler
2) I aligned the crank belt mark...before I was only looking at the two cam marks on the belt and didn't really look at the crank belt mark. I may have not had the right amount of slack where it should have been.
3) I pulled the tensioner pin before manual turning the motor over. I didn't want to risk having to remove the tensioner again but honestly I have now taken that on and off so many times it's not that bad.
4) I used the crank bolt to turn the motor. Before I was using a cam sprocket tool to manually turn a cam. Could the crank have jumped a tooth because of this, who knows.

Anyway, I was thrilled that it finally worked and more so that the motor fired up and ran great. I thought it would because I was very careful and spent almost as much time on the internet researching as I did wrenching but I was under a lot of time pressure to get it done. Son takes the truck off to college ten hours away this weekend. Thanks for the replies.

Jay