Timing Belt Question

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  #1  
Old 08-03-06, 12:52 PM
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Timing Belt Question

I have seen from many places including repair manual, forum, and internet discussion. They all said need to locate top dead center before removing/replacing timing belt. I am wondering if you remove/replace a timing belt and don't rotate any pulley why do you need to locate TOC since timing belt is the same? Just want to clear my question! Thanks!
 
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Old 08-03-06, 02:23 PM
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The reason for that is I 'd guess that would make it easier and piece of mind that you know you install the belt correctly by ligning up all marks, or damage to the valves will occur if belt not lign up right, most of the engine especially v6's and v8's when you remove the timing belt, the camshaft may turns to "rest position" due to one or more of the cam lobes were on the edge of the cam(holding by the belt) and when you remove the belt, the camshaft will jumps a bit but it's enough to give you a headache.

Most of Nissan v6 and Chry/dodge with twin cam engine will jumps/turns when timing belt remove, some of isuzu v6 will also turns but depending on the position of the cams before remove, if it turns when the belt is removed, it's going to be a big mess. I guess it's kinda better safe than sorry thingy.
 
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Old 08-03-06, 04:09 PM
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Thanks! That make sense to me know.
 
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Old 08-03-06, 04:15 PM
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I have opened timing belt cover to check the TDC for my 1995 Camry V6. According to repair manual, two marks on two pulleys have to be on the top to locate TDC. I tried to turn pulley while timing belt is still on and I have found they are not exactly point to the top at the same time after timing belt makes a full turn. Does that mean I have timing off? However, everything looks normal to me. It it is off, how I can adjust it?
 
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Old 08-04-06, 05:26 AM
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...and not only that, but what if the vehicle in question had a timing belt replaced at some other time and it was done incorrectly, you'd never know...

for the record, many OHC timing marks are not perfect and will not line up perfectly...also the angle that you see them from can skew your perception of "properly lined up". putting the belt on more than once trying to perfectly line up the marks is sometimes the only way to assure that they are indeed lined up as close to perfect as possible.
 
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Old 08-04-06, 10:40 AM
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Originally Posted by carguyinva
...and not only that, but what if the vehicle in question had a timing belt replaced at some other time and it was done incorrectly, you'd never know...

for the record, many OHC timing marks are not perfect and will not line up perfectly...also the angle that you see them from can skew your perception of "properly lined up". putting the belt on more than once trying to perfectly line up the marks is sometimes the only way to assure that they are indeed lined up as close to perfect as possible.
I bought this car new and never have any problem with timing belt. I checked timing belt it is because of manufacture recommand to replace every 60K miles. My car has 69K now. Yes, I don't drive it a lot. That is why it only has 69K for 11 years. The timing belt still look very good condition except TDC mark doesn't line up perfectly ( I look at each mark right on top of center pulley). For the situation like mine, would timing off a little bit since timing belt never been broke/change and comes with factory installed? If it is off, how can I adjust it myself, difficult or easy? I can tell I am very handy person.
 
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Old 08-04-06, 03:44 PM
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Any pic available?.
 
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Old 08-04-06, 04:17 PM
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if its 11 years old and has 69000 miles on it it is time to change the belt even if it still looks good.
belts stretch some over time so the marks may not be perfectly lined up but should be close less than one sproket tooth off.
 
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Old 08-14-06, 07:53 AM
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timing belt

the only adjustment you may have is tension...there is no adjustment to make the marks line up. less than one sprocket tooth is correct.

tension is critical so make sure you have the manufacturers procedure reviewed and ready to refer to if you need it and also the correct tools.

bejay is also correct about age of the belt...not only is it overdue by mileage, it's old...you're on borrowed time
 
  #10  
Old 08-14-06, 06:22 PM
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This will not work on all cars but if it will work on yours it is slick. First verify that the belt is timed correctly. Like carguyinva said sometimes the angle you are looking from makes the marks look off but they may be correct. What I use sometines is a small piece of metal or anything that is perfectly straight. Hold it flat on the valve cover gasket surface if that is the side the timing marks are on the sprocket. Keeping it flat on the gasket surface slide it over to the mark on the sprocket and see if it is lined up right.

After you are sure it is ligned up right on some cars you can take a razor blade and split the old timing belt down the middle and then take the outer half off. This leaves the back half still on the sprockets keeping the sprockets in time.

You may need to loosen the tensioner a little. Then slide the new belt 1/2 way on. Then cut the the old belt and remove it from the sprockets. Then slide the new belt the rest of the way on. Adjust the tension per the specifications and you are done.

If this won't work on your car you can do the following after you are sure the old belt is timed correctly. Use brake cleaner or something to get any oily residue off of the crank sprocket and any other sprocket tht needs to be in time. Don't worry about the water pump if your belt drives it. Take some fast drying paint. I use white. Paint a tooth on each sprocket. That paint a stripe on the old belt that is in line with the tooth and mark the out side of the belt. Take the old belt off and carefully lay the belts one on top of the other so all the teeth are lined up. Transfer the paint marks to the new belt. So you don't get them mixed up you could use a different color for each sprocket. Mark the corresponding out side of the new belt with some paint.

Let it dry. Then just put the new belt on with the paint marks matching, adjust the tension and you are done.

Also on many cars you can carefully remove the seal on the idler pulley(s) and put some grease in the bearing and then carefully put the seal back on. If the idler pulley freezes up due to lack of grease it will break the belt. It takes a tiny screw driver to do this and you must be careful not to bend the seal as it is very easy to bend. You have to carefully push the outer edge of the seal back in it's groove and be sure it is fully seated. This works on many types of bearings like serpentine belt idlers, alternator bearings etc. You have to know what you are looking at because some seals are crimped around the out side and this will not work, but I have found that most are removeable.

Don't bother doing this unless the bearing spins smoothly. If it is rough at all the grease will help but the bearing will eventually fail.
 

Last edited by car nut; 08-14-06 at 06:43 PM.
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