timing off by one tooth is OK?
08-24-2010, 07:35 AM
#16
Drifting
Thread Starter
No need for the flywheel lock - you're done with that.
What Dan's saying is to loosen the tensioner, then, with the slack in the belt, you'll be able to kind of move the belt so the next tooth lines up with the cam gear, and then a little bump of belt will "inch worm" around to the other side of the cam gear.
(After loosening the tensioner, this will make slack on the water pump side... if you need to jump teeth in the other direction, use a crescent wrench on the cam nut, or the crank nut, to move the slack to the top side of the belt. And, Dan's right, don't turn things over too much - just a little wiggle to play with the belt.)
What Dan's saying is to loosen the tensioner, then, with the slack in the belt, you'll be able to kind of move the belt so the next tooth lines up with the cam gear, and then a little bump of belt will "inch worm" around to the other side of the cam gear.
(After loosening the tensioner, this will make slack on the water pump side... if you need to jump teeth in the other direction, use a crescent wrench on the cam nut, or the crank nut, to move the slack to the top side of the belt. And, Dan's right, don't turn things over too much - just a little wiggle to play with the belt.)
I would still have to re-tension and then turn engine over by hand again once I'm done re-tensioning right?
and then, since my mark on the cam gear is 1 tooth to the right of the mark on the cam housing, I would need to move it back by 2 teeth? 1 to go back to TDC, and 1 more so that its 1 tooth before TDC but before tensioning?
08-24-2010, 08:35 AM
#17
Rennlist Member
You're making it overly complex. If the crank is at TDC, and the cam gear is only 1 tooth off, then you only need to adjust it by 1 tooth.
The marks are fixed on the flywheel and cam gears. They don't "move" - they should each line up to their respective positions properly. (You've watched my video, right?)
Think of it this way: the distance between each timing belt tooth is a fixed distance. With the crank and cam lined up with their marks, there will be a specific # of timing belt teeth between the 2 pulleys. You either have it set up so there is 1 tooth less, or 1 tooth more "occupying" that fixed distance - so, the result is the cam's timing mark doesn't line up when the crank's does.
Also, after you set the tension, you should turn the motor over several times - not just 1 revolution. Then you should check the tension again. Turning it over will help the belt find the "path of least resistance" on the pulleys - meaning the spot on each pulley where it's running in a flat plane.
When you're putting it on, it's usually *not* exactly on that flat plane... you set the tension, let it find it's "running groove" and then you find it's a little looser.
This is a set, check, recheck, recheck type of job.
The marks are fixed on the flywheel and cam gears. They don't "move" - they should each line up to their respective positions properly. (You've watched my video, right?)
Think of it this way: the distance between each timing belt tooth is a fixed distance. With the crank and cam lined up with their marks, there will be a specific # of timing belt teeth between the 2 pulleys. You either have it set up so there is 1 tooth less, or 1 tooth more "occupying" that fixed distance - so, the result is the cam's timing mark doesn't line up when the crank's does.
Also, after you set the tension, you should turn the motor over several times - not just 1 revolution. Then you should check the tension again. Turning it over will help the belt find the "path of least resistance" on the pulleys - meaning the spot on each pulley where it's running in a flat plane.
When you're putting it on, it's usually *not* exactly on that flat plane... you set the tension, let it find it's "running groove" and then you find it's a little looser.
This is a set, check, recheck, recheck type of job.
08-24-2010, 10:06 AM
#18
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Get the crank mark dead on.
Mark on the timing belt at the cam TDC mark. Use a sharpie.
Loosen the belt and hop the sharpie mark over to match the mark on the cam sprocket.
Retension (just use the twist quickly) and turn the engine over four times, check the marks again. the sharpie mark will have wandered off but the matchmarks on the sprockets and engine should all (nearly) line up.
Once it is right, tension properly. Avoid the temptation to set it wicked tight so it'll be right when it breaks in. Bad bad things can happen with all that pressure on the water pump and cam snout.
*Note* the cam timing being nearly half a tooth off is not uncommon. As the belt stretches, tension is taken up on only one side of the belt so the timing will shift a few degrees.
Getting the timing off by one tooth during this job is common as people set the timing before they pretension the belt so the cam shifts clockwise when the belt is tensioned. No big deal.
-Joel.
Mark on the timing belt at the cam TDC mark. Use a sharpie.
Loosen the belt and hop the sharpie mark over to match the mark on the cam sprocket.
Retension (just use the twist quickly) and turn the engine over four times, check the marks again. the sharpie mark will have wandered off but the matchmarks on the sprockets and engine should all (nearly) line up.
Once it is right, tension properly. Avoid the temptation to set it wicked tight so it'll be right when it breaks in. Bad bad things can happen with all that pressure on the water pump and cam snout.
*Note* the cam timing being nearly half a tooth off is not uncommon. As the belt stretches, tension is taken up on only one side of the belt so the timing will shift a few degrees.
Getting the timing off by one tooth during this job is common as people set the timing before they pretension the belt so the cam shifts clockwise when the belt is tensioned. No big deal.
-Joel.
08-24-2010, 06:14 PM
#19
Drifting
Thread Starter
see, I was thinking that it would take 1 tooth to get back to TDC, and 1 more tooth before TDC so that next time I retension the belt and rotate the engine by hand - the marks line up
wrong?
also, would I need to move my timing belt 1 tooth to the left or to the right? I think it would be counter clock-wise (left), since I am 1 tooth to the right from TDC mark right now
and I really don't want to come off as a retard, but I do try to be as "****" as I can be, I hate to screw things up ...
wrong?
also, would I need to move my timing belt 1 tooth to the left or to the right? I think it would be counter clock-wise (left), since I am 1 tooth to the right from TDC mark right now
and I really don't want to come off as a retard, but I do try to be as "****" as I can be, I hate to screw things up ...
Last edited by roman944; 08-24-2010 at 08:21 PM.
08-24-2010, 10:23 PM
#20
Rennlist Member
If you line the crankshaft mark up, and the camshaft mark is to the right of the housing mark, you need to turn the cam counter-clockwise 1 tooth.
If the camshaft mark is to the left of the housing mark, you need to turn the cam clockwise 1 tooth.
If you do it properly, the camshaft pulley mark will line up with the mark on the housing and the flywheel mark will line up with its reference point.
That's all anyone will be able to tell you without seeing the car. Trust your eyes. If they don't line up, take the belt off and try again!
If the camshaft mark is to the left of the housing mark, you need to turn the cam clockwise 1 tooth.
If you do it properly, the camshaft pulley mark will line up with the mark on the housing and the flywheel mark will line up with its reference point.
That's all anyone will be able to tell you without seeing the car. Trust your eyes. If they don't line up, take the belt off and try again!
08-28-2010, 12:50 PM
#22
Drifting
Thread Starter
ok, so I am at it again
now, after I set the tension, tighten the tensioner etc, is there any way to double check if I did everything right?
like if after I have the tension and tensioner tightened, I put the arnworx tool on again with reference bar, and then take the measurement without the reference bar, it should be close?
or would that be wrong?
now, after I set the tension, tighten the tensioner etc, is there any way to double check if I did everything right?
like if after I have the tension and tensioner tightened, I put the arnworx tool on again with reference bar, and then take the measurement without the reference bar, it should be close?
or would that be wrong?
08-28-2010, 05:03 PM
#23
Drifting
Thread Starter
just tried to start the car, for some reason it seems to me that the belt keeps tensioning itself ...
cam cover is off, the belt spins, the marks align perfect, everything seems fine, except that the belt feels a little bit tighter then after I set the tension - and yes, we did turn it over by hand a few times before trying to start the car
what could be wrong? or is this how it's supposed to be and we should keep trying to start the car? because we stopped once I felt that the belt got a little tighter
cam cover is off, the belt spins, the marks align perfect, everything seems fine, except that the belt feels a little bit tighter then after I set the tension - and yes, we did turn it over by hand a few times before trying to start the car
what could be wrong? or is this how it's supposed to be and we should keep trying to start the car? because we stopped once I felt that the belt got a little tighter
Last edited by roman944; 08-28-2010 at 05:23 PM.
08-28-2010, 05:41 PM
#24
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If it is a spring tensioner, make sure that the lock nut is tightened down so the spring is not continually trying to hold the belt tension. If it is not the spring tensioner then did it move from your locked position when the car was running? Maybe retension, mark the location of the tensioner nut and run it again to see if the adjustment is slipping.
08-28-2010, 07:50 PM
#25
Drifting
Thread Starter
its an early car, so no auto tensioner
keep in mind this is my first belt job ever, maybe its all fine, and the belt simply got a little tighter?
my dad took off the spark wire in the middle of the spark plug wires to turn the car over with starter without starting it yet, and I felt the belt and it got a little bit tighter then when I first set the tension
just not sure if its "safe" to keep going to try and start the car, or is something wrong ...
keep in mind this is my first belt job ever, maybe its all fine, and the belt simply got a little tighter?
my dad took off the spark wire in the middle of the spark plug wires to turn the car over with starter without starting it yet, and I felt the belt and it got a little bit tighter then when I first set the tension
just not sure if its "safe" to keep going to try and start the car, or is something wrong ...
08-28-2010, 11:35 PM
#26
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My 2 cents
I just did this in my first car as well and I feel your pain. I was agonizing over it for days before I got up the nerve to start it. I think, from my current understanding, (mostly from here) that if the tension is off by a little bit the car is fine to start and drive for a short time. It may whine if you get the balance belt too tight and running it hard for extended periods is not ideal. However, if you can turn it over by hand with minimal resistance (IE no valves colliding with the pistons) then you should be good to start it up and drive it gently to the porsche shop and pay them to tension it for you. I got mine tensioned for only $75 which is cheap peace of mind to me.
08-29-2010, 12:39 AM
#27
Drifting
Thread Starter
I just did this in my first car as well and I feel your pain. I was agonizing over it for days before I got up the nerve to start it. I think, from my current understanding, (mostly from here) that if the tension is off by a little bit the car is fine to start and drive for a short time. It may whine if you get the balance belt too tight and running it hard for extended periods is not ideal. However, if you can turn it over by hand with minimal resistance (IE no valves colliding with the pistons) then you should be good to start it up and drive it gently to the porsche shop and pay them to tension it for you. I got mine tensioned for only $75 which is cheap peace of mind to me.
thanks!
