![]() ![]() So I'll probably test that theory out tomorrow. It may be that I didn't get the crank pulley quit on as far as I should, and that there is a little back and forth play in the crank sprocket which only shows up after the belt warms up and loosens a little bit. After another five minutes or so ( 15m total since starting the engine ) the noise was again very distinct. At that point I noticed that the t-belt was slightly oscillating back and forth on the idler pulley ( video ) in the plane tangential to it's point of contact. So there was no noise until about ten minutes after I started the engine, when I could start to slightly hear the same click clacky knocking kind of noise, which seemed to be coming from the bottom end. So before starting the engine up I pushed the belt toward the engine a bit both at the idler pulley and at the cam sprocket. Only had about twenty minutes to mess with this today, but I noticed before starting the engine up that the t-belt was hanging about a millimeter off the edge of the idler pulley: As a side question, can I safely drive this thing around till I get this noise figured out? However, I ran across this other post which says the bearings should not spin freely and in fact should stop almost immediately. So I'm wondering if the bearings in my tensioner and idler pulleys are somewhat worn out to the point that the the pressure from a brand new belt is sufficiently greater than the pressure from the old belt and that's making them make noise where they didn't make noise before. However, when I spun them they only turned a few times before stopping, which is in contrast to what I'm seeing in this video in which the guy spins a t-belt pulley and it spins freely for quite a while. I didn't hear any noise so I figured they were good. When I tested the tensioner and idler I spun them and listened for any noise. However you can hear the noise very clearly in the video. ![]() I also took an approximately one minute video of the belt with the engine running and there is no wobble in the belt and no noticeable movement of the tensioner or tensioner spring. I've run the belt maybe ten minutes total, and the outside part which contacts the tensioner and idler pulley already has this kind of smudged look to it ( don't know if that shows up so well in the picture ). So I pulled off the valve cover and upper timing cover and took a look at the belt: Here's a picture of how I got the tensioner spring on by holding the tensioner with a zip tie: I'd really like to hear what people think as I'm a bit afraid to drive it till I figure out what this noise is and I don't want to just throw parts at it. ![]() I'm thinking that if the noise really is the belt flopping around, then maybe even though there was 100% no noise like this before, and even though the tensioner spring looked fine, maybe it's just not strong enough to deal with a brand new belt? I don't know what's normal here, I don't have any basis for comparison. The other thing I noticed was that after I removed the zip tie, the tensioner moved back quite a bit, and the tensioner spring was maybe stretched to 2.5 times it's resting length. I put the belt just a little bit over the cam sprockets first, then worked it fairly easily a little onto the crank sprockets, then went around with a rubber mallet gently tapping it into place, a little at a time. The things that somewhat stood out to me where that it was fairly easy to get the new belt on ( most people said it was a real PITA ), I simply used the allen wrench to turn the tensioner left until the allen wrench hole was exactly to the left of the tensioner bolt. I reused the tensioner, the spring and the idler pulley as they all seemed to be in good condition, although I've never done this before so what do I know. I never heard such a sound from that area before. If I had to guess, I would guess it was the sound of the timing belt flopping around due to it being loose. At some point I noticed a strange sound which seemed to be coming from the timing belt area. I had been running the engine for a few minutes, revved it up to around 3k rpms a few times and started and stopped it a few times. I just changed the timing belt and water pump on my 98 Mazda 626.Īfter I got everything reassembled I started up the engine. ![]()
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