I think the belt itself is jumping a tooth on the crank pulley when I try to pull it more taught over the exhaust pulley. The crank pulley is staying in place. I’ll try to give it another shot tonight after work.
I think the belt itself is jumping a tooth on the crank pulley when I try to pull it more taught over the exhaust pulley. The crank pulley is staying in place. I’ll try to give it another shot tonight after work.
eastsideTim said:I think the belt itself is jumping a tooth on the crank pulley when I try to pull it more taught over the exhaust pulley. The crank pulley is staying in place. I’ll try to give it another shot tonight after work.
As you pull it up, just taught enough so there's no "slack" on that side, shouldn't need McGilla Gorilla effort. I also had the crank front bolted on, so that might've helped keep the belt in place on the crank.
Goes super fast; for reasons I'll skip here, I wound up setting the belt twice, quick the first time, faster the second.
The belt is on, and I think in the correct position. When at TDC, the exhaust cam appears straight up, and there are 19 teeth between the hashmarks on the cam. The problem is in the tensioning. I turn it 1 5/6 of teh way through (until the crank pulley notch lines up with the offset mark. Release the tensioner, and it barely moves. Tighten it, and rotate 2 1/6 till I am back at TDC. I end up with the exhaust cam fine, but the intake is off a smidge, and there is slack in the belt between the cams. Does anyone have any idea if I am doing something wrong, or is it possible that the tensioner spring just needs to be replaced, as I had suspected earlier. Or is there supposed to be this much slack (I doubt it)?
Regarding the tensioner - When I am pressing it outwards to lock it into the low tension position, I can press it out and hold it with just one finger. Is that a sign the spring is too weak? I'm kind of assuming right now, that when I release the tensioner, it just doesn't have enough strength to pull against the valvetrain.
I'm not familiar with Miata belts, but I know that some tensioner springs are just a convenience to help move it into position. Of all the tensioner styles I've seen, if it has a pulley with an oblong hole or an offset center, the proper tension comes from prying and setting the tension yourself, then tightening the bolt. The spring is just there to prevent the mechanic from needing three hands.
It would take a monster spring to tension a belt, as in you would have to pry it to get the tension off. I find it hard to believe that a spring would instantly fail 90% of it's force. They're pretty simple things.
In reply to Curtis73 :
Yeah, that's what the Miata spring does, just moves the tensioner into position. There's no prying done. I think the idea is that at 1 5/6 turns of the crank, there's not supposed to be a significant load from the cams pulling on the belt. So it is still quite possible I have something else messed up or that everything is fine), but if I do, I have no idea.
When you follow the turning procedure, then tighten the tensioner, is the belt properly tensioned?
The left cam in the picture you just posted still looks a half tooth off to me, but it may be camera position.
Oh, and I just looked again. That belt is not tensioned properly in this picture:
A properly tensioned belt is always tight between the gears, regardless of crank position.
Unless you're working on a DSM, but that's a different story.
In reply to Curtis73 :
Okay, that was my concern. My thinking is that since the tooth count between the gears is correct, that the spring couldn't pull the tensioner pulley in as close as it should be, and at TDC, all the slack (that shouldn't exist) is up between the gears. So, I may have the belt on right, based on tooth counts, but it just isn't tensioning the belt correctly, and letting the exhaust cam advance based on the load from the valve springs. Or I have something else royally messed up.
What I would try first is to loosen the tensioner bolt and rotate the left cam back. That will A) move the timing mark to line up correctly, and B) put slack on the tensioner side allowing it to further adjust. If that makes things line up, you at least know you have the teeth right and you can try spinning it and reseting the tensioner.
If I were tackling that job (now that I've googled it) I would set the crank to TDC, then belt on the right cam while turning it to match up the marks. Zip ties, then place it on the left cam while turning it to line up. Zip ties. Then along the open tensioner and loosen the bolt to let it pull on the belt. Then do the spin 1 5/6 and tighten the tensioner. If that doesn't do it, something is wrong.
Another trick I sometimes did (if you know the number of teeth like you do) is to use chalk or a sharpie. The first cam is pretty easy. The second cam can seem like it needs three hands and a removable eyeball, so if you count the teeth and mark on the belt and the second cog, you can do it without contorting to look at the timing mark while you wrench.
Looking at that photo, it looks like the left cam would be lined up if you turned it backwards to remove that slack. My guess is that you tightened the tensioner at a time when the valvesprings were pushing the left cam forward instead of backward.
eastsideTim said:Regarding the tensioner - When I am pressing it outwards to lock it into the low tension position, I can press it out and hold it with just one finger. Is that a sign the spring is too weak? I'm kind of assuming right now, that when I release the tensioner, it just doesn't have enough strength to pull against the valvetrain.
I'm a little confused when you say "lock it in low position" - I didn't lock the tensioner putting the belt on, I did not have the spring on at all.
Once I got the belt on, I put the spring on, turned the crank a couple revolutions.
Belt should be tight across the top, and once it is, I locked the tensioner pulley.
Once the belt is tight, the cam gear marks will line up.
The spring isn't especially strong, but I don't know about one finger.
Curtis73 said:What I would try first is to loosen the tensioner bolt and rotate the left cam back. That will A) move the timing mark to line up correctly, and B) put slack on the tensioner side allowing it to further adjust. If that makes things line up, you at least know you have the teeth right and you can try spinning it and reseting the tensioner.
If I were tackling that job (now that I've googled it) I would set the crank to TDC, then belt on the right cam while turning it to match up the marks. Zip ties, then place it on the left cam while turning it to line up. Zip ties. Then along the open tensioner and loosen the bolt to let it pull on the belt. Then do the spin 1 5/6 and tighten the tensioner. If that doesn't do it, something is wrong.
Another trick I sometimes did (if you know the number of teeth like you do) is to use chalk or a sharpie. The first cam is pretty easy. The second cam can seem like it needs three hands and a removable eyeball, so if you count the teeth and mark on the belt and the second cog, you can do it without contorting to look at the timing mark while you wrench.
Looking at that photo, it looks like the left cam would be lined up if you turned it backwards to remove that slack. My guess is that you tightened the tensioner at a time when the valvesprings were pushing the left cam forward instead of backward.
If there are 19 teeth between the marks, don't do anything with the belt/gears.
Leaving the tensioner pulley bolt loose, just turn the crank and the spring will pull the belt in (or should), and it should line up pretty when done.
In reply to OldGray320i :
I was meaning pushing the tensioner out to where there is the least tension on the belt.
So, just leave the bolt loose, and rotate it that way until the spring pulls the tensioner in? Then lock it there?
eastsideTim said:In reply to OldGray320i :
I was meaning pushing the tensioner out to wear there is the least tension on the belt.
So, just leave the bolt loose, and rotate it that way until the spring pulls the tensioner in? Then lock it there?
Yes. As you turn it, the spring will put the tension on the belt. I think it took a couple full turns on the crank to put it nice.
I watched a couple you tube videos to get up to speed. They show the person pulling on the tensioner with one finger, but they have to pull pretty hard; like wrap their finger around it and you can see their muscles shake a little when they pull.
Skip to 14:00 in this video to see how hard he pushes to move the tensioner. Not a ton of force, but you might get an idea to compare with your finger.
In reply to Curtis73 :
He looks like he’s putting noticeably more effort into pushing the tensioner than I have to, especially since I don’t have much hand strength. I’m leaning towards just going ahead and ordering a new spring.
You know it's the right thing to do. You can spend the next year watching amateur YouTube videos, but it's not going to change anything. Just get a new spring. How old is the current one, 26 years?
In reply to Keith Tanner :
Yup, that’s what I’ll be doing. On the off chance I haven’t messed this engine up already, I really don’t want to have to ever open it up again.
You can't mess it up by mucking around with cam timing. It's non-interference.
Keith Tanner said:You can't mess it up by mucking around with cam timing. It's non-interference.
I’m more worried about my earlier work replacing the valve stem seals and cleaning the HLAs.
Ordered the spring, and a new dipstick, since I figured, why not after having to use the one with the broken handle the entire time I’ve owned the car. Hope to get them in a couple of days.
The spring is out for delivery! If I have time tonight, I will attempt to get the car timed, and start putting other parts back together. Might actually have the car off jackstands this weekend, even if not everything I wanted to do over the winter is accomplished.
I await great success!
Okay gang, I'm about to lose it here. I think I have it right, but only by doing it the wrong way. Which has me worried I screwed something else up. The new spring was stronger, but didn't really make a difference.
Here's the procedure I had been using:
That resulted in this again:
Based on the video Curtis linked, and another I checked, people are leaving the tensioner bolt loose while turning the crank, then tightening it later. So, I gave that a try, and reversed steps 6 and 7 above. Here's what I got:
The angle makes the intake cam look off, but it is lined up on the mark. I can press down fairly hard on the belt with a thumb and get around 1/4"-3/8" deflection. Everything looks right now me.
So, either I've been doing this wrong the whole time, or there's a chance I messed something else up. Just in case, here's a picture of the cams at TDC, do they look like they're in the right position?
Is there anything else possible that I've messed up, or should I just button it up and see what happens?
I don't care what the repair manual says, alter your process to this:
I just switched 6 and 7. Turning the crank without tension on the belt doesn't make sense to me. If you do it your original way, the left cam can turn farther forward against the valve spring tension and put slack between the two. The reason that the tensioner only moves a tiny bit is because the tensioner spring isn't as strong as the valve springs. It can't pull the left cam back to its proper place and you end up with slack in the belt.
I'm convinced that it's timed correctly but not tensioned correctly. I'm not sure why they want you to turn it without tension on the belt.
You can try to start it since it isn't an interference engine (I don't think it is) but you're just asking to damage the belt.
Follow my suggestion above and spin it as many times as you want. You'll probably notice the tensioner pulley moving in and out as it fights against the valve springs. Turn the motor until the tensioner pulley is at its furthest to the right. My guess is that you'll find (as you turn the motor) that maybe you're going just a tiny bit more than 1 5/6 turns? Maybe the left cam is kicking over a valve spring and popping forward?
Edit... just read you already tried switching 6 and 7.
Grab the belt between the tensioner and the exhaust gear. Maybe two fingers on the block side and your thumb on the front. Twist it. Does it twist 1/4 of the way (90 degrees) and then get really hard to twist further?
If so, that's about right.
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