Emergency Belt Tension Needed
05-21-2004, 05:32 AM
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Emergency Belt Tension Needed
Had new belts put on about 500km's ago. I've just started noticing a tapping type sound coming from around the timing cover. Took the timing cover off tonight and found the timing belt is slapping the cover just below the distributor. I don't really want to drive it the way it is, and the only way to get it to my mechanics on Monday is to drive. I'm planning on upping the tension on the belt until Monday when he can look at it.
Problem is I don't have any of the tensioning tools normally used yet, so...
if anyone knows how I'd go about setting the tension by hand, using the twist method or however it is done, I' d be much appreciative.
Problem is I don't have any of the tensioning tools normally used yet, so...
if anyone knows how I'd go about setting the tension by hand, using the twist method or however it is done, I' d be much appreciative.
05-21-2004, 07:34 AM
#2
Pat944,
Yes, your belts are WAAAY too loose. I did mine about 600 miles ago, used the TLAR method, "that looks about right" to tension them. You want the timing belt tight enough that it is somewhat difficlult to push far enough to hit the cover, if it is singing too much, it's too tight, if it is flapping at all, even if not hitting the cover, it's too loose. Balance belt should be just tight enough that it's not singing, mine still is tho, and not flapping.
Hope this helps you get to the shop safely. Don't take this method as gospel, it's what I did, and so far seems to be working ok. I believe a little tight, especially with fairly new belts, is better than too loose. And oh by the way, the timing belt tensioner tightens counter clockwise and the balance belt tensioner tightens clockwise, for what it's worth.
Good luck and hope this helps,
Bill
Yes, your belts are WAAAY too loose. I did mine about 600 miles ago, used the TLAR method, "that looks about right" to tension them. You want the timing belt tight enough that it is somewhat difficlult to push far enough to hit the cover, if it is singing too much, it's too tight, if it is flapping at all, even if not hitting the cover, it's too loose. Balance belt should be just tight enough that it's not singing, mine still is tho, and not flapping.
Hope this helps you get to the shop safely. Don't take this method as gospel, it's what I did, and so far seems to be working ok. I believe a little tight, especially with fairly new belts, is better than too loose. And oh by the way, the timing belt tensioner tightens counter clockwise and the balance belt tensioner tightens clockwise, for what it's worth.
Good luck and hope this helps,
Bill
05-21-2004, 08:47 AM
#3
Are you going back to the same mechanic for the retension? If he put new belts on and they are slapping the covers after only 500 km. then he did something way wrong. They should not loosen up anywhere near that fast. 1500-2000 miles is a normal retension period. What some people don't realize is how important it is to set the engine to TDC then back it off 10 degrees when setting timing belt tension. Try it yourself. Feel the tension at TDC then back it off and see how loose it gets. If you're going be using the 90 degree twist method then at least make sure you are doing it at the right spot.
Everything else that's been said is pretty much correct for using a TLAR. I know of more than a few timing belts tensioned like that though that left the cylinder head looking not right at all. 944's are hampered by the lack of a hydraulic timing belt tensioner that keeps a constant load on the belt as it stretches making the initial tension very critical.
One more thing, for a short drive to the mechanic, having it on the tight side won't hurt anything but don't go overboard.
Everything else that's been said is pretty much correct for using a TLAR. I know of more than a few timing belts tensioned like that though that left the cylinder head looking not right at all. 944's are hampered by the lack of a hydraulic timing belt tensioner that keeps a constant load on the belt as it stretches making the initial tension very critical.
One more thing, for a short drive to the mechanic, having it on the tight side won't hurt anything but don't go overboard.
05-21-2004, 10:19 AM
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Tighten the timing belt until it becomes extremily difficult to turn the water pump pully (if not impossible) by hand. That will get you about 95% dead on, if not perfect. The balance belt should be significantly more loose and you should be able to almost twist the belt 180 degrees at it's longest stretch.
05-21-2004, 10:48 AM
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If the edge of the timing belt has migrated off of the cam pulley in either direction and hitting the covers there is something seriously wrong with the belt tracking.
Could be too tight. Could be the crank pulley flange/washer has been put on wrong (if you also had a front seal replacement). You can take the top section of the belt cover off and look around inside with a torch (flash light) and check the tension pulleys.
The one for the timing belt has to have it's single guide flange on the inside toward the engine. Balance belt tension pulley flange is on the outside.
In one occasion I was sold a bad belt that was cut from the tube at an angle. Had serious tracking problems.
Could be too tight. Could be the crank pulley flange/washer has been put on wrong (if you also had a front seal replacement). You can take the top section of the belt cover off and look around inside with a torch (flash light) and check the tension pulleys.
The one for the timing belt has to have it's single guide flange on the inside toward the engine. Balance belt tension pulley flange is on the outside.
In one occasion I was sold a bad belt that was cut from the tube at an angle. Had serious tracking problems.
05-21-2004, 11:42 AM
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Originally posted by Headhunter
Tighten the timing belt until it becomes extremily difficult to turn the water pump pully (if not impossible) by hand. That will get you about 95% dead on, if not perfect. The balance belt should be significantly more loose and you should be able to almost twist the belt 180 degrees at it's longest stretch.
Tighten the timing belt until it becomes extremily difficult to turn the water pump pully (if not impossible) by hand. That will get you about 95% dead on, if not perfect. The balance belt should be significantly more loose and you should be able to almost twist the belt 180 degrees at it's longest stretch.
No way, 90 degrees works with the Balance belt too.
The tension on the Balance shaft belt is not nearly as critical as the timing belt. The only function of the balance belt is to turn two shafts that have basically no load on them. If the balance belt sings then you can loosen it (or more likely) you set the idle roller incorrectly.
180 degrees sounds WAY too loose.
Either way it doesn't really matter. It's a non critical belt, as long as it doesn't snap.
Dal.
05-24-2004, 09:24 AM
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It got to the mechanics today, he had the Haynes, Factory Manuals, and the steps from Clarks Garage when he did the tension. He did loosen it off a bit when it was whining a little bit so that's probably what has caused it to loosen so quickly.
