Oil Leak - 99 A6 2.8 - Comming from crank seal or upper oil pan seal?
08-02-2013, 08:14 PM
#42
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Location: Auburn, GA
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I have replaced the timing belt on these motors three times without removing the cam gears with no problems.
Question, if the cam gears on these motors are not keyed how are you supposed to reposisition them for TDC, normally you would turn the cam gears. If they are free spinning, how do you align them correctly with each gear. Seems like opening a can of worms to me for no reason.
The belt tensioner keeps the correct tension on the belt and since each component spins independently (with the belt off) physics shows that the belt tension would be even at all locations.
When the timing belt is replaced, especially and intact one, the engine is at rest with the sprockets in their proper positions. The belt can be replaced with little or no movement to the crank and a least one cam gear. The motor should not even realize anything has been done to it, if it is done right.
Any further information to the contrary would be invited. Thank you.
Question, if the cam gears on these motors are not keyed how are you supposed to reposisition them for TDC, normally you would turn the cam gears. If they are free spinning, how do you align them correctly with each gear. Seems like opening a can of worms to me for no reason.
The belt tensioner keeps the correct tension on the belt and since each component spins independently (with the belt off) physics shows that the belt tension would be even at all locations.
When the timing belt is replaced, especially and intact one, the engine is at rest with the sprockets in their proper positions. The belt can be replaced with little or no movement to the crank and a least one cam gear. The motor should not even realize anything has been done to it, if it is done right.
Any further information to the contrary would be invited. Thank you.
08-06-2013, 08:42 AM
#43
AudiWorld Super User
The sprockets only spin freely once they have been "popped". They aren't keyed, but have pressurized face plates. Once you loosen the bolt you see that the plate with the two eyes can only go on one way. The purpose of popping them is to prevent even one tooth of error. The cam locking bar is used to set and hold TDC (if belt is off or previous belt job was bad). If the belt is still on, TDC is set by turning the crank pulley.
But to educate you a little you are in fact a little off on your response anyway.
The reason the cams are not keyed to sprockets is because the timing requires a much more precise alignment than just one tooth or the other. The cams are infinitely adjustable once they are released from the sprocket. The alignment tool fastens to the cams NOT the sprocket. So you can align the cam timing right on the money. Then you can set the tension of the belt perfectly with the "popped" as you call them sprockets.
So once the tool has set the timing right on the money , and the tensioner has set the tension of the belt perfectly independant of the cams .. then and only then , the sprockets can be tightened to the cams , with everything in perfect harmony, Any method other than this in my humble opinion is a back yard hack atempt at fixing cars and these people should stick to hondas ..
Last edited by Airbag; 08-06-2013 at 08:44 AM.
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