Timing belt walking off gears
 

So, I just got my engine put together and i've driven it about 15 miles now. When I popped the hood to check everything out, the timing belt was almost off of the pulleys. It has worn a slot in my timing covers. Does anyone have any ideas what might be causing this?

The tensioner could be loose.

Well thats not good at all. For sure check the tension and make sure its still tight. Otherwise, I don't know what would cause the belt to walk.

I suppose a misaligned crank sprocket wobbling could cause it to come off too, but unlikely that's it.

I will check the tension. Any tips on exactly how to check it? I mean, it feels about right. I did reuse my old tensioner spring (about 80k miles old) but I put a little bit more pressure on it when I torqued the tensioner bolt so that it would be good and tight. It doesn't sing like I have heard overtightened belts do.

Any chance you bent one of he cam gears when removing the belt? Maybe prying a gear off a cam for some crazy reason? Any misalignment of the gears themselves relative to one another or an untrue gear could cause walking.
The belt it self could also be to blame do to some material irregularity causing it to apply pressure on one side more than other or maybe when it was cut there was some type of failure.
I assume there are no obvious signs of irregular wear on the belt giving you any idea of where the pressure causing it to walk is coming from?

If you look straight down at the belt you should be able to see a gear wobble as the belt walks as well.

Well, this is a head I bought on craigslist, so let's hope they're not bent. The cam gears do not wobble. I'm not sure about the crank pulley but it's an ATI super damper. I will take a look at it in the morning. There is also a fuel leak that I need to fix before running the motor again.

DO NOT put extra tension on the tension pulley, it says that right in the manual. The spring is all the tension it needs. While you're redoing your timing belt, double check everything it rides on is flat and turns true.

I will go back and loosen the tensioner and re-torque it. The reason that I put extra tension on it was because I figured the spring was worn out.

Maybe they didn't drop the head on the cam gears and bend them. For sure look them over closely.

damn im stumped wes

Haha that's not what I like to hear. It's all good. Tomorrow, I will check to make sure the gears are true, make sure the crank pulley is straight, re-torque the tensioner and idler and check them with a straight edge.

is it cuase you didnt wanna get rolled by goverment cheese at hardinsburg?
Good that site is growing on me, i sure hope fly gets some damn money to buy my trans am between you and me i have my doubts. :(

Haha, I don't get the whole "government cheese" thing. Yeah, deals like that rarely work out.

In my Integra, my timing belt too would walk. I notice that one of the gears towards the edge was damaged (flat spotted). I replaced that.

Not sure if Miatas have this, but there were 2 plates near the crank that would sandwich and re-align the belt. The belt would go slightly off near the cam gears, but get re-aligned w/ the plates at the crank. I had them installed backwards.

I'd probably check the tension first.

I have seen incorrect tension on the belt do this on some engines. Follow the belt tension procedure to the letter, I bet that will do it. Why not get a new spring to ease your mind on that part as well.

Ron

Sounds like you haven't followed the manual properly. There is a specific set of steps to do to tension the belt properly. I'd suggest following them and see what happens then. Of course there is always the possibility that the belt will continue to track now since it was adjusted that way to start with.

If you replaced the water pump, make sure that it is flat against the block and that there is no dirt under the base of the idler or tensioner pulleys.

I pulled the idler and tensioner off and put them back on. I checked the cam gears with a straight edge, they were fine. The crank pulley doesn't wobble. I took some videos and pictures.



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A. Use your camera's flower button.
B. I have no idea what your problem is.
C. Your poor starter and battery.

The 2nd video is really confusing. It walks towards the right immediately, than slowly walks left. Do you have access to a mag base and indicator? I'd check flatness of both pulleys and all 3 sprockets. Not 30 minutes ago I finished installing my own timing belt. After a minor hiccup with one of the cam sprockets being on incorrectly (smoke out the air filter:giggle:), it started up immediately and didn't budge. I double checked cause I had this thread in the back of my head the whole time.