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Loose timing belt

Discussion in 'General Tech and Maintenance' started by sbaker0421, Jan 14, 2004.

  1. sbaker0421

    sbaker0421 Junior Member

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    The timing belt on my 91 crx si is loose from the camshaft pulley straight down to the crankshaft pulley(edge that drops straight down closest to front). Is this a problem? If so what are some potential reasons for this to happen? Thanks
  2. endlesszeal

    endlesszeal Senior Member

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    shit loads can go wrong.. it happened to my gf.. the alternator belt went flying, lights came out, you can get crank walk, and ur engine will basically fall apart..
    it could be just a worn out belt or u didnt tighten it enough.
  3. Loco Honkey

    Loco Honkey Banned

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    Don't post unless you know. I'm not even going to take the time to go through all your symptoms and why they're completely wrong, but to everyone reading this, DO NOT take his post to be true in any way, shape, or form.
  4. Loco Honkey

    Loco Honkey Banned

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    Now for the real answer...

    How loose is loose? It's a vague term, and you speak in generalities. With the engine off, turn the crank by hand one complete turn and then check the deflection of the tension side of the belt (the side you're worried about). Deflection shouldn't be more than a few mm. Now... there will be minor slack on the back side of the belt (the side facing the firewall), and if that slack is taken up by the cam turning on it's own (it'll do this due to pressure on the cam lobes from the rocker arms), the slack will be transferred to the tension side.

    If the timing belt skips a tooth on the cam or crank gear, your valve and ignition timing will be retarded 9° (9° of timing per tooth). Refer to your shop manual that you should have regarding setting the timing properly. If it skips one tooth, which is most likely what happened if your engine is running rough, but runs, no damage has occured. If it skips more than one tooth, you could have bent some valves. however... on the few D series engines I've built, I've tested the "interference" theory by positioning a valve so it's at the top of the lobe, and then SLOWLY rotating the crank a few turns (with the timing belt off). Nothing happened. So, I'm going to go out on a limb here and guess that even if the timing belt breaks, nothing would happen. However, it's never happened to me, so I can't say for sure.
  5. cws13

    cws13 Senior Member

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    If a belt breaks something will happen because rods stretch slightly. Based on physics they weigh a ton at BDC and TDC. Outside of that Honkey is on the money. I just wanted to add and say... Do not retighten your belt, get a new one. It will stretch and break. renewing it will add a good bit of performance. Mine was soo stretched from abuse that at 60K the car would barely make it off line at a stop light or up the driveway.
  6. endlesszeal

    endlesszeal Senior Member

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    im just giving some advice from what ive experience..
    my gf and i were driving down the 5 going to six flags.. i see the battery light come on and have no idea.. i referred to the manual and it suggested i pull over if it was on continously.. i followed the suggestions, popped up the hold and the alternator belt was missing.. i had no fucking clue.. lucky (good and bad) i was near a shop.. i asked the guy to look at it and he was gonna start busting up.. i asked why.. he said we were even lucky to have made it to where we were.. 80 miles from home... he continued to explain to me that something was wrong with the timing belt, it wasnt tightened enough when it was replaced and that it fucked up everything else.. the power steering belt all fell apart too.. on top of that, a "keyway" (does it exsist?) was missing from the crank pulley.. he said the crank couldve walked and fell out too and all hell would break loose. neway, he fixed it for 200 fucking bucks, and it was only a bandage.. we got home and took it to a REAL shop, one not so ghetto and out of no where, and spend another 500 to fix it and take out home made keyway that was jammed in the crank..

    cliffnotes:
    -driving, battery light came on
    -pulled over like the manual told me to do
    -mechanic said the engine was lucky to be together
    -diagnosis (sp) was loose timing belt
    -bandage it up for 200
    -600 to fix bandage and fix problem

    so i took his word for it, since he did have an ASE certificate.. could mean shit, but he looked more knowledgable than i did.. could simply just stated i was wrong and didnt have to be a fucking asshat..
  7. sleepercivic

    sleepercivic Senior Member

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    timing belt broke on my d16z6 with 183k miles on it, it broke at about 4k rpm and I did not bend any valves, guess I got lucky, it was on its 2nd belt
  8. cws13

    cws13 Senior Member

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    Very lucky, I have seen some breaks get away with out bending valves- but it is rare. Hell, we just did 2 VW Gti's that were supposed to be non interference that bent valves.

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