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Timing Belt Slack Explained [Merged 6-7] loose cam sag sagging sprockets gears

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defbear

20+ Year Contributor
93
0
Oct 16, 2002
here, California
I was just wondering if its normal for the timing belt to have some slack after its been sitting over night. I have been checking it for the past few days. When the car has just been shut off and for a few hours after its nice and tight with virtually no play. But in the morning when I check it there is some, not alot, but some play. More than just after its been driven. The timing belt and tensioner were replaced about 2000 miles ago. Anyone have any ideas?
 
Might wanna re-check it just to be safe, but after I did mine and saw that I freaked out and searched everything to find that its fairly normal. I even checked the tension on all of my friend's DSMs and theirs did it too.
 
cool, ill recheck it, however im not freaking out as much now. BTW, I see you live in K-ZOO, thats only about an hour away from me. I live in Eau Claire, 15 minutes outside of Benton Harbor.
 
yeah i honestly dont think it has anything to do w/ hot or cold. its just weird, when its loose, just barely tap the key to make it turn over, oh about a quarter of a turn and its right back to tight again.
 
In your pictures, I see that you are checking the belt tension between the intake and exhaust cam gears The tensioner does not have enough power/strength to bend the cam gears radially. If you think about it there is no adjustment between the two cam gears, and it is a fairly shot span for the timing belt (between the two gears). You could pull long and hard on the timing belt below the cam gears, and never come close to stretching the belt enough, or bend the cam gear teeth relative to the cam gear center hub to tighten the belt between the two gears.

After the car sits one or both of the cams is most likely rotating slightly, depending on where the cam lobes are in relation to the valve spring/rocker assemblies.

Did you by chance have the block decked, head milled, use a different thickness head gasket, or a combonation of them during the motors life?

After you set the timing belt tension, how far out did the tensioner piston protrude? Did you set the timing belt tension in inch pounds at the tensioner pulley to the specification? Which way did you rotate the tensioner pulley to set the timing belt tension?

I have seen this before, and it could be just the cams moving after the motor sits a while, or it could be a timing belt tension adjustment issue.

Since you don't live too far away form the Grand Rapids / Muskegon area, and if you want a second opinion, you would be welcome to bring the car by.
 
Big Woo said:
In your pictures, I see that you are checking the belt tension between the intake and exhaust cam gears The tensioner does not have enough power/strength to bend the cam gears radially. If you think about it there is no adjustment between the two cam gears, and it is a fairly shot span for the timing belt (between the two gears). You could pull long and hard on the timing belt below the cam gears, and never come close to stretching the belt enough, or bend the cam gear teeth relative to the cam gear center hub to tighten the belt between the two gears.
I don't know what that was supposed to be about, but read Posts #7 and #17. It's nothing mysterious, it occurs with chain-driven cams as well- but they aren't out in the air to see.
 
I agree that it is nothing mysterious, and that it does happen with other engines as well. While I also agree that the motors tend to stop in roughly the same position often, and cam wind can also add to the condition. However if the exhaust cam is to move toward the intake cam while the motor is at rest, then there must be sufficient slack, or perhaps a lack of tension on the timing belt between the exhaust cam gear, and the crank gear. I.E. over the tensioner, tensioner lever, and tensioner pulley. Otherwise there would be no where for it to go.
 
Big Woo said:
I agree that it is nothing mysterious, and that it does happen with other engines as well. While I also agree that the motors tend to stop in roughly the same position often, and cam wind can also add to the condition. However if the exhaust cam is to move toward the intake cam while the motor is at rest, then there must be sufficient slack, or perhaps a lack of tension on the timing belt between the exhaust cam gear, and the crank gear. I.E. over the tensioner, tensioner lever, and tensioner pulley. Otherwise there would be no where for it to go.

I agree. If the belt had sufficient tension on it, then there would be no slack for the cams to "move a bit" and the tensioner would or should, keep the cams "pulled" into place w/ no slack anywhere.
 
Hi all, i am in the middle of my timing belt(s) replacement. When i got the gaurd off...i decided to check the tension on the Timing Belt. It was loose, Loose enough for it to slide off of the idler pulley. I did not pull it off, i quit about half way through. IS THIS NORMAL?

More Detail: The timing belt was replaced @ 102000 KMH (before i owned it). The belt actaully looks good, the tensioner does not look fairly new however. I will be replacing it, but this brings me back to the original question.

I personally dont think it is normal for the belt to be that loose. What are your thoughts?

Thanks!

GRsDSM
 
Its not normal for it to be that loose. I would check to see if the auto tensioner is still good. Compress the piston coming out of it, if the rod doesn't move back slowly it is time for a new one. Also the belt just might have not been tensioned right before. If you need iformation how to replace the timing belt, there is a good write up on this website and there is also one on vfaq.com
 
the idler pulley side will be somewhat loose when you start it, shut it off, and then let the camshafts go into the resting position, mine has never been loose enough to slide it off of the idler pulley itself, but it still has a bit of slack in it... i have changed my timing belt 4 times now (trying to diagnose a problem, and had to pull the belt off to replace the waterpump, another time to straighten out the crankshaft backplate, and another time to do something, i dont remember) so if you have any questions, PM me and i can help you out if you don't quite understand the service literature... it's really not that hard if you ask me, but the first time involved alot of thinking, just make extra damn sure that you set piston 1 at TDC on the compression stroke before you start loosening the belt and messing with other things..... otherwise you have a little bit of thinking and work ahead of you (i would know haha)
 
I did a timing job without using the tensioner rod and a few weeks later my belt became relaly loose. I ordered the rod did it over and no problems anymore.
 
I forgot the exact name. The "special" tool your suppose to use. The one that looks like a rod with thread on one end. See vfaq.com under timing belt you'll see which one it is.
 
There is an alternate tool made by Snap On, and may also be available at places like NAPA. It's a handle with the two fork prongs that fit into the holes for the tensioner wheel, and you can turn it that way.
 
But thats not what i asked...Not what Guys used to provide tension, but if the belt should be that loose.

Sorry dont mean to be a Jack_ss...but can i get more feedback from you guys on the original topic please.

Thank!
 
Optimally, you should have a belt tension checker (it's kind of like a spring scale with a hook that is handheld) to check the tension on the belt. The amount of tension is listed in the service manual. If you can't do that, you can guestimate it by eye. What I do is once everything is tight, push the belt down directly between the cams. if it bows more than about 10-15 degrees, it's too lose. Retighten.


DISCLAIMER: Use at your own risk.
 
I dont think i will have means of getting such a tool on the limited time that i have. However, visualy looking at the tension on the belt via flex seems like what i am going to have to do.

Furthermore, i got the crank sprocket off just to find that the balance shaft is in very bad shape! So much for the dealership to do both of the belts at the same time ARG!!! :mad:
 
i just replaced my cracked valve cover and when i looked at the timing belt i noticed that it has about half an inch of slack both ways between the two cam gears. It does not seem to be sliding off but there is still slack. I am going on a long trip tomorrow and was wondering if there should be slack there
thanks for the info
anton
 
Hey guys,

Just wondering how much tension the timing belt should have at the top b/w the crank wheels?

I changed my timing belt (and balance belt) a few weeks ago and I thought that all went well.

Today I decided to take the top cover off to check things out and I noticed that there is quite a bit of play at the head between the 2 crank wheels.

I also noticed that the idle seems a bit off, it seems to miss at low rpms...

Could it have already skipped a tooth?

Should I drive the car if the belt is loose?


Thanks for the help
 
"Deep breath"

Ok, it's not abnormal to have some "slack" between the cam gears. It all depends how the cams fall when engine comes to a stop. Remember you have 16 valve springs pushing on the cam lobes all over the place.


However, if you are unsure, it's a lot easier to take the cover back off and make absolutely sure.

Now, did you replace the auto tensioner? You should if you don't know the when it was replaced last.

Also, do you know how to set the auto tensioner properly so it can make full use of the little amount of stroke it has in taking up the slack in the belt when it stretches?

Let us know.

Good Luck
 
The timing belt tensioner should be just as important as chaning the belt itself. The tensioner relieves pressure of the belt and assists it in guiding the belt around the motor. If the tensioner goes bad the belt wobbles and contributes to jumped timing, missed teeth and engine functionality issues. good luck man. :thumb:
 
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