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i install the timing belt but now that i resolved a problem i got another one. i replced all the idler pulleys but i didnt replaced the tensioner. the timing belt is rubbing against the block and is breaking apart. what can cause the belt to move side to side on the pulleys. the pulleys are not bend

I've always wondered what stops the belt from slipping off too.

If I look at the top of my cam gears, it wiggles a bit on there, but it never falls off. Obviously. Or I would have noticed. But then again, I have been driving around with a massive obvious intake leak and my TPS unplugged for at least a week....

I would think tension is what keeps the belt where it is. Otherwise it would be an epic fail by the mazda engineers. I'm assuming the force of tension is strong enough to hold the belt in place as it moves no matter what angle the car is at. I would check the tension.

i leaning to a bad tensioner but some body also told me that theres a plate that goes on the block that helps keep the belt from moving side to side. somebody must have done this belt before cause the timing belt cover was been hold by 3 screws and i dont see the black plate on the block.

Which pulleys? There's a lip on the cam pulleys so it can't come off there, and the crank pulley is so small that the belt can't bend enough to slip off it with a proper tensioner.

None of my pullies have a lip (BP) but on the crank gear, there is a little dome shaped disk that is on the crank pully side, and it has black marks on it like the belt rubs it sometimes.


Even with massive tension, a belt could still slip off. Ever used a poorly adjusted belt sander? Maybe its different with teeth.

Alignment is what keeps the belt on. If any of the pulleys is out of alignment it will work its way off. If it's coming off, something is not straight. Period.

wytbishop wrote:Alignment is what keeps the belt on. If any of the pulleys is out of alignment it will work its way off. If it's coming off, something is not straight. Period.

Hahah obviously! I was assuming he put everything on right

wytbishop wrote:Alignment is what keeps the belt on. If any of the pulleys is out of alignment it will work its way off. If it's coming off, something is not straight. Period.

everything is allign correctly. it only does it when you give it gas

I'm not trying to accuse you of doing a poor job. It's just that there is no other reason for that belt to come off. That's it. Something is not straight. It may only be when you accelerate, but one way or another, something is not straight.

I remember reading about how people have had a tough time getting that last pulley on... Since you have to hold the belt and push down quite a bit before it will start to thread into the block. It's easy to cross-thread this pulley (same with the tensioner) which can cause just a small amount of wiggle or a misalignment of the pulley. This would cause it to slip off.

OR.... where did you buy the pulley kit from? It could be lop-sided pullies

Like it's been said, something in there is causing it to rub (i.e. pushing it against the block). Check your items and make sure you buy a quality belt too (if you didn't the first time).

Good luck

mazdags94 wrote:I remember reading about how people have had a tough time getting that last pulley on... Since you have to hold the belt and push down quite a bit before it will start to thread into the block. It's easy to cross-thread this pulley (same with the tensioner) which can cause just a small amount of wiggle or a misalignment of the pulley. This would cause it to slip off.

OR.... where did you buy the pulley kit from? It could be lop-sided pullies

Like it's been said, something in there is causing it to rub (i.e. pushing it against the block). Check your items and make sure you buy a quality belt too (if you didn't the first time).

Good luck

Are you talking about the idler pulleys? Both times I did my timing I never head to take a single one off, I don't see why everybody says you need to do it.

When I replaced my timing belt and re-did my head gaskets, I removed the idler pullies....

I just went by what the workshop manual said.

Another thought, your cam gears could be wiggling a bit. or that little "tic tac" looking pin could be off a bit (on the end of the cam, where the cam gear bolts on) causing a slightly raised portion of the cam gear. Or it could cause the cam gear to wiggle.

This is one of those small but very annoying problems that causes bigger issues....

when tightening the alen bolt on the tensioner pulley. the pulley it self it doenst move. if that happens how is the tensioner going to put tension on the belt cause the pulley wont move cause being tight

As a rule of thumb, everytime your car needs a replacement timing belt you should also replace the tensioner - hence all the timng belt kits available.

Ive seen cars where the tensioner was put on the reverse, causing the tensioner to rip into the belt and make it shudder. Im not sure if this is possible in our cars as i havent done my timing belt yet, but i would say it is.
if you havent touched the tensioner, you probably should - it's a good place to start, and i would say if you're replacing the timing belt, tensioner should def. be new too.

Good luck.

melb30x