OK...I set the notch in the crank pulley to the 0 marker on the lower timing belt cover.....but the dots on the cam gears are not lined up with the dots on their timing cover...no marks on the cheap belt used. So i went ahead and removed the crank pulley and i need to now how to make sure this thing is top dead center. Is their a mark on the crank gear, bc i dont see one. I need to know before i remove the timing belt.
Also....i cant quite seem to understand how this autotensioner works....i see the nut on the side of it that looks like it pushes the pulley. The gap between the arm and that little rod piece is 4mm....so do i just bolt up to the motor and remove the nut i was talking about....rotate the crank and make sure it is still at 4mm??
Do i need to remove the spark plugs....some say yay, some same nay.
Whats the best way to measure the deflection in this belt? (noobish i know)
Sorry for the load of question....but like i said in another post.....immm so nervous, but i got a guy helping me part time who owns a 88 shiro special who knows a good bit....trying to learn about this. Thanks guys.
Working on Timing Belt Job (TDC and tension)
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dantesdoom
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- Car: 1991 Nissan 300zx N/A
1997 Nissan Pickup
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marty1mc
- Posts: 733
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- Car: 1990 Nissan 300ZX TT - Z owner since 2003
- Location: Fuquay Varina,NC
Re: Working on Timing Belt Job (TDC and tension)
First, NEVER use the backplate marks to set cam timing. They are completely inaccurate. On my motor, the left side of the motor lined up and the right side was off 2 teeth. Use the lines on the timing belt to set the cams in relation to each other and the crankshaft. Also, if in doubt, count teeth between the cam marks and the crank mark.
The tensioner requires a 6mm bolt to be inserted in the top to adjust the tension. Be very careful, as tightening it too fast will break the tensioner. I usually turn it 1/4 turn or so and wait 5 secs, do it again. You will feel the tensioner get firm when you turn it, stop and wait. Forcing it in will break the casting. Look at the top of the tensioner from the top of the motor and you will see a hole that is threaded.
Edit for clarity: The head of the bolt is 10mm, but the bolt itself is a 6mm.
The tensioner requires a 6mm bolt to be inserted in the top to adjust the tension. Be very careful, as tightening it too fast will break the tensioner. I usually turn it 1/4 turn or so and wait 5 secs, do it again. You will feel the tensioner get firm when you turn it, stop and wait. Forcing it in will break the casting. Look at the top of the tensioner from the top of the motor and you will see a hole that is threaded.
Edit for clarity: The head of the bolt is 10mm, but the bolt itself is a 6mm.
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dantesdoom
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- Joined: Wed Mar 04, 2009 7:28 am
- Car: 1991 Nissan 300zx N/A
1997 Nissan Pickup
Re: Working on Timing Belt Job (TDC and tension)
OK....i got the s*** all put back together but i have three questions...
The belt and the marks on the pulley WERE perfectly aligned....after rotating the motor by hand twice, they no longer aligned.... the same after another two rotations.....is this normal? Still match up on the back back plate dots/notches.
The tensioner has 3.5 mm gap on the rod....is this close enough to 4 mm or should i redo it...an how would i go about it...there is little movement to fix the tensioner.
I set the belt on the center of the sprockets/gears....after several rotations it moved more to the front of the them....all the way against the lip on the exhaust sprockets/gears. Is this normal as well.....
thanks and thanks for the info so far!
The belt and the marks on the pulley WERE perfectly aligned....after rotating the motor by hand twice, they no longer aligned.... the same after another two rotations.....is this normal? Still match up on the back back plate dots/notches.
The tensioner has 3.5 mm gap on the rod....is this close enough to 4 mm or should i redo it...an how would i go about it...there is little movement to fix the tensioner.
I set the belt on the center of the sprockets/gears....after several rotations it moved more to the front of the them....all the way against the lip on the exhaust sprockets/gears. Is this normal as well.....
thanks and thanks for the info so far!
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robomatic12
- Posts: 672
- Joined: Sun Jul 12, 2009 12:05 pm
- Car: 1990 300ZX TT
Re: Working on Timing Belt Job (TDC and tension)
That is normal, they will never line up again for the next XXXX amount of rotations so that the timing belt wears evenly.
I believe the spec is betwen 3 and 4mm but no more than 5mm so you should be good.
You should be able to see where the old belt was wearing a mark on the sprocket, that is probably fine as I think mine is closer to one side of the sprockets than the others.
I believe the spec is betwen 3 and 4mm but no more than 5mm so you should be good.
You should be able to see where the old belt was wearing a mark on the sprocket, that is probably fine as I think mine is closer to one side of the sprockets than the others.
Re: Working on Timing Belt Job (TDC and tension)
The marks on the timing covers are simply for a reference to know your in the right neighbor hood when you line up your cam sprockets before putting on the belt. After that forget about the marks on the timing cover. Line the marks on the belt with the marks on the sprockets, make sure they are perfect. Theres a circle dot on the crank sprocket. If you cannot see it, flip your crank sprocket because you have mounted it backwards. TDC #1 will be about 5 oclock where the dot should be. if you line the crank pulley to the 0 timing mark on the plate before removing it you will be at TDC. Another way to be positive is to pull the spark plug out of the #1 cylinder and shine a light down there and turn the crank till you see its approx TDC. Regardless the belt marks line up with the sprocket marks thats all thats important. The auto tensioner is exactly that, it applys the correct ammount of tension to the timing belt. just make sure its not completely pressed in all the way. I would screw the bolt in so its sucked in half way then release the bolt once the belt is installed correctly and it will do the rest.