Timing belt tension

[SHOMON]

Hi folks. I' m doing the timing belt in my 95 atx. I also put in a brand new tensioner from FORD. So I purchased the tensioner tool from Mark at RCM to make sure I don't over tension the belt. The chiltons says to torque the tensoiner to 4.3 inch pounds, great. Now where can i find an inch pound beam type torque wrench(thats what is in the picture in the chiltons)that goes that low? I work at an auto dealer and none of the techs have one that goes that low. I figured I would try here to see what people can come up with. Thanks Tim

 

[sdpatt]

The gas piston in the tensioner provides all the pressure on the belt once the installation is complete. The only real change you can make that affects the final tension is the position of the eccentric hub of the tensioner pulley. If your old tensioner had failed a bearing or piston (the only reasons you'd replace one), just note the position of the hub on the old tensioner and rotate the new tensioner pulley's hub to the same orientation.

There is some good information in this old topic.

 

[SHOMON]

Thanks Scott but yes i did replace the hydraulic tensioner and just the pulley so that is the problem. While I was in there i put a new belt on. In that old thread you said to put the larger part of the eccentric down but that would make it to loose no? The little piston only moves 1/4 inch maybe max so, I think the preload/pretension of the belt would be very important to insure against premature wear.

 

[sdpatt]

The piston moves only about 3/8", but the tensioner is a lever arm that amplifies the motion at the pulley. Position the eccentric so that once the belt is installed and the pin is still retaining the piston of the tensioner, that the pulley is gently taking out most of the slack from the belt. That way, when the pin is removed from the piston, the pulley has plenty of range to provide tension on the belt.

As I wrote in that old topic, the closer the pulley is to the tensioner arm pivot point (lower region), the more leverage it has and the more tension the pulley can apply to the belt. The limiting factor is the range of motion of the piston/lever arm. If the piston is allowed to reach the end of its travel, the belt will not be adequately tensioned. The positioning of the eccentric hub would therefore be dependent on the overall length of the timing belt. They should be close to the same length, but a millimeter shorter or longer can make a difference in the position of the tensioner.

The 3.2L has the longer replacement interval for the timing belt compared to the 3.0L because of the constant load tensioner and the second idler pulley on the tension side of the belt to minimize the belt spans and vibration.