I just replaced a timing belt. I need opinion regarding the procedure. I did it not the first time on my car. As usual, I removed the spark plugs, then peeled off the old T-belt, replaced roller-idler with a new one, fitted a new timing belt, released the idler and run about 5 full rotations of the crank shaft with 22mm wrench in order to let the new timing belt seat properly over crank shaft pulley, camshaft pulley and the roller-idler. Of course, I checked all the notches for timing. I did not lock the idler yet. Then I installed the spark plugs and run few rotation of the crank shaft. And what I noticed.
When a piston in one of the cylinders reaches TDC there is significant force required to turn the crank shaft and at this time incoming branch (view from the top of the motor) of the TB getting loosened and the idler moves about 1/8 of an inch toward a generator because the tension spring pushes the idler and this keeps tension of the belt constant. This condition I call “preloading”. After TDC is passed almost no force needed to rotate the crank. And tension difference between incoming and out-coming branches of the TB equalizes and the roller moves back about 1/8 of an inch. So I always lock the idle while keeping the TB “preloaded” with the wrench on the crank shaft. I think, this makes TB tension constant during spinning. Am I right?
Thank you.
When a piston in one of the cylinders reaches TDC there is significant force required to turn the crank shaft and at this time incoming branch (view from the top of the motor) of the TB getting loosened and the idler moves about 1/8 of an inch toward a generator because the tension spring pushes the idler and this keeps tension of the belt constant. This condition I call “preloading”. After TDC is passed almost no force needed to rotate the crank. And tension difference between incoming and out-coming branches of the TB equalizes and the roller moves back about 1/8 of an inch. So I always lock the idle while keeping the TB “preloaded” with the wrench on the crank shaft. I think, this makes TB tension constant during spinning. Am I right?
Thank you.
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