timing mark problem
05-14-2003, 02:36 AM
#1
2nd Gear
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timing mark problem
hello, can anyone help me. i am replacing the timing belt on my 84 944 w/automatic trans. if i allign the timing marks on the flywheel and the cam then place the belt on, i can only turn the engine about 1/4 turn before it stops and i can feel the pistons contacting the valves. i also have noticed that when the flywheel timing mark is alligned the #1 piston isnt at TDC. is this normal? is it posible that the flywheel is some how put on wrong so that the mark isnt at the right position? thank you for any responces.....
05-14-2003, 04:32 AM
#2
Nordschleife Master
Do a search on past threads on Timing belt; read everything you can, then go to <a href="http://www.clarks-garage.com" target="_blank">www.clarks-garage.com</a> and make sure you cross ref everything!
Do not do anything more before you read up more!!!!
I just did my Timing belt, balance belt, and alt/air belt on Friday, and there are more than ONE marks that need to be lined up, and kept that way!
Something is off; I have done my Celica Timing belts twice, and 1/4 forward and 1/4 backward on Cylinder one, and it never hit anything.
There is a hole in the back of the engine, near the passenger compartment that will also show you that it is lined up. Also the balance belt pulley must be lined up.
And I can't remember if there was one other, but I do remember that the balance belt needed a little more slack than the Timing belt.
Please do not do anything else until you read, and make sure you understand, and read again.
- Julie
Do not do anything more before you read up more!!!!
I just did my Timing belt, balance belt, and alt/air belt on Friday, and there are more than ONE marks that need to be lined up, and kept that way!
Something is off; I have done my Celica Timing belts twice, and 1/4 forward and 1/4 backward on Cylinder one, and it never hit anything.
There is a hole in the back of the engine, near the passenger compartment that will also show you that it is lined up. Also the balance belt pulley must be lined up.
And I can't remember if there was one other, but I do remember that the balance belt needed a little more slack than the Timing belt.
Please do not do anything else until you read, and make sure you understand, and read again.
- Julie
05-14-2003, 05:44 AM
#3
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Well this is somewhat of a strange problem, because in my opinion it is not possible to put the flywheel, cam- and crankpulley the wrong way on the shafts. However if you remove the flywheel location dowel it is possible to install it incorrect. This is also the case for the woodruff key on the crankshaft en camshaft.
Normally lining up the marks should result in a good installation of the timing belt. First be sure you're looking at the correct marks, and be sure there line up with the marks in the housing. For the crank there is the OT mark at the flywheel, look throught the belhousing hole at back of the engine near the speed/reference sensor.
For the cam there is the stripe on the pulley (remove the pully housing for a good look)
To check if the pistons are really set at TDC, remove sparkplugs (this wil ease rotating the engine) Insert a long screwdriver through the sparkplughole in #1 cylinder, the screwdriver should be at its highest point, verify this by moving the crank a few degrees clockwise and counterclockwise.
For the cam remove the plugs on the camhousing,
the following rules apply for the camshaft/cilinder positions:
Just as the piston starts moving downward in the intake stroke (called top dead center, or TDC), the intake valve would open. The intake valve would close right as the piston bottoms out.
The exhaust valve would open right as the piston bottoms out (called bottom dead center, or BDC) at the end of the combustion stroke, and would close as the piston completes the exhaust stroke.
Look inside the holes in the camshaft housing and verify if the #1 intake camlobe is pointing down (thereby pushing the intake valve open) if the #1 piston is at TDC.
I used this procure for my old 924 when the previous owner put the campulley on backwards and I couldn't get the timingmarks to line up. Be carefull with the 944, valves can hit pistons, for the 924 this is not the case so putting you're timing wrong will not destroy the valves
Good luck and keep us posted!
Normally lining up the marks should result in a good installation of the timing belt. First be sure you're looking at the correct marks, and be sure there line up with the marks in the housing. For the crank there is the OT mark at the flywheel, look throught the belhousing hole at back of the engine near the speed/reference sensor.
For the cam there is the stripe on the pulley (remove the pully housing for a good look)
To check if the pistons are really set at TDC, remove sparkplugs (this wil ease rotating the engine) Insert a long screwdriver through the sparkplughole in #1 cylinder, the screwdriver should be at its highest point, verify this by moving the crank a few degrees clockwise and counterclockwise.
For the cam remove the plugs on the camhousing,
the following rules apply for the camshaft/cilinder positions:
Just as the piston starts moving downward in the intake stroke (called top dead center, or TDC), the intake valve would open. The intake valve would close right as the piston bottoms out.
The exhaust valve would open right as the piston bottoms out (called bottom dead center, or BDC) at the end of the combustion stroke, and would close as the piston completes the exhaust stroke.
Look inside the holes in the camshaft housing and verify if the #1 intake camlobe is pointing down (thereby pushing the intake valve open) if the #1 piston is at TDC.
I used this procure for my old 924 when the previous owner put the campulley on backwards and I couldn't get the timingmarks to line up. Be carefull with the 944, valves can hit pistons, for the 924 this is not the case so putting you're timing wrong will not destroy the valves
Good luck and keep us posted!
05-14-2003, 09:21 AM
#4
Burning Brakes
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with the engine at TDC #1 the cam lobe for the intake valve on #1 will NOT be pointing down and opening the valve, both valves will be closed at this point. I suspect that the mark you are using on the flywheel is not the TDC mark, there should be a line scribed and the letters OT next to it. You can use the screwdriver trick to get you in the neighbourhood and then very slowly turn the engine over while looking for the mark. It is not possible to put the flywheel on wrong as the bolt pattern is not symetrical, if the flywheel was mistimed the engine would not run because the signal from the reference sensor would be mistimed also. Good luck Mark T.
05-14-2003, 09:57 AM
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I'm not sure about the automatic, but I used the timing mark on the bottom of the flywheel. There's an inspection hole on the bottom center of the bellhousing. The timing mark is a slot about 1/4" wide, it needs to be centered in that hole. Also, if you didn't lock your flywheel before you started, you could be 180 degrees off with the crankshaft, it turns twice to one revolution of the cam. Sorry about the huge avatar, I'm going to try to downsize it later today. Good luck.
Arne.
Arne.
05-14-2003, 12:08 PM
#6
Drifting
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by avainio:
<strong>it (flywheel) turns twice to one revolution of the cam. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">i couldn't get my marks lined up until i realized that.
Arne, your car looks sharp.
<strong>it (flywheel) turns twice to one revolution of the cam. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">i couldn't get my marks lined up until i realized that.
Arne, your car looks sharp.
