Timing belt slack.
#1
Rainman
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I did a full rebuild on my motor between 5000 and 10,000 miles ago and recently noticed a difference in sound from my timing belt. I was very used to the high-pitched whine it would make but lately it is a lower sound. Being a string musician (orchestra) I associate a lower pitch with a looser string (in this case a belt). I will be needing the car for the next few days for work. What are the odds that a belt, properly tensioned at time of installation, would fail/slip after 10,000 miles of stretching?
Hopefully I can tear into the front end on Monday.
Hopefully I can tear into the front end on Monday.
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I'm assuming you were using new timing belts at the time of rebuild. Did you check your tension after the first 1k? The belts are going to stretch a bit over 10k, the reason why tensions for new belts and used belts are different. I'd double check the tension on those belts just to be sure they aren't too lose just to play it safe.
#5
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Very cool.
I'd check and perhaps retension the belts. After schwank and I did my cam gasket we had to reinstall the timing belt, belt had a high pitched whine at 2000 RPMs for a while untilit broke itself in.
I'd check and perhaps retension the belts. After schwank and I did my cam gasket we had to reinstall the timing belt, belt had a high pitched whine at 2000 RPMs for a while untilit broke itself in.
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Always retension your new belt after 1k miles (Porsche requires it). I just did a full change about 800 miles ago and I can hear the difference in the sound and getting ready to retension mine.
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#10
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New belts get scary loose after a few hundred miles. Since it only takes 10 minutes I retensioned mine at 500 and 1000 miles, easier to do that than keep the revs down and be paranoid. If you commute in your car 1000 miles should be no problem since you'll put on some lazy miles pretty fast. Actually 1000 miles is probably fine any old way but you might be pretty taken aback by how loose it gets.
Some wrenches put them on really tight and let them wear and stretch in, I think this is pretty dumb. Puts too much pressure on the waterpump, crank/cam snout, etc.
-Joel.
Some wrenches put them on really tight and let them wear and stretch in, I think this is pretty dumb. Puts too much pressure on the waterpump, crank/cam snout, etc.
-Joel.
#11
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That's your problem. I initially set my last belt to 4.0 on the 9201 scale, as per the factory instructions. In 1200 miles, it was about a 1.5. Spec on a used belt is about 2.7, I think (off the top of my head).
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He's right. These things should really sound like sewing machines. BTW, are you sure it's the timing belt you're hearing and not the balance shaft belt?