cam belt tension

[davemaxx]

i have noticed that when the engin is cold the cam belt seems a bit slack at the center of the longest free part, just less than a 90 degree flex, between top pulley to bottom pulley, when i start the engin for a few seconds and then stop it, the slack has gon, is this natural? as if when the engin is off the tensioner relaxes with the tension of the belt pushing down on it, so the belt becomes slightly slack, and then when the engin is running and the pulleys and guide wheels spinning and the belt running free floating smoothly the tensioner takes up that bit of slack. the belt was changed about 6 months ago and it looks perfect.

[plumb bob]

i have noticed that when the engin is cold the cam belt seems a bit slack at the center of the longest free part, just less than a 90 degree flex, between top pulley to bottom pulley, when i start the engin for a few seconds and then stop it, the slack has gon, is this natural? as if when the engin is off the tensioner relaxes with the tension of the belt pushing down on it, so the belt becomes slightly slack, and then when the engin is running and the pulleys and guide wheels spinning and the belt running free floating smoothly the tensioner takes up that bit of slack. the belt was changed about 6 months ago and it looks perfect.

Did you change the tensioner and idler when you did the belt??

[davemaxx]

no because on inspection they were fine, looked as good as new, so did the cam belt, but i changed it as a matter of course when i bought the truck, i just never noticed this when i did the job, i had a look at it this evening through curiosity just to see if the belt was cracking , polished or hardening 6 months after fitting it. it looks as good as new, still got chalk finger prints on it from where i marked the pulley wheels, and the engin runs and performs as sweet as a nut, touch wood.

[BUSHWHACKER]

Did you change the tensioner and idler when you did the belt??

It's a different style of tensioner on the 3.0.

[davemaxx]

does my description of how its working sound right or is it ,or has it lost its pushing power and need replacing, the manual says that to preload it befor fitting, it will need a force of betwwen 100 - 1000 KGF to push the piston back in. that isn't realy helpull to me because i squeesed it in with a vice and put the pin in the hole and then fitted it and pulled the pin, 100 to 1000 KGF seems like a massive allowance,
there is a tollerance for the mximum extension of the piston on it while its off and its 8.9mm, i have measured it while its on this evening and its well within this 8.9mm and i can see that the piston has extended foreward from the preloaded position, so i can assume that it hasnt jammed up, and it is pushing against the ideler pulley after pulling the pin.

[BUSHWHACKER]

does my description of how its working sound right or is it ,or has it lost its pushing power and need replacing, the manual says that to preload it befor fitting, it will need a force of betwwen 100 - 1000 KGF to push the piston back in. that isn't realy helpull to me because i squeesed it in with a vice and put the pin in the hole and then fitted it and pulled the pin, 100 to 1000 KGF seems like a massive allowance,
there is a tollerance for the mximum extension of the piston on it while its off and its 8.9mm, i have measured it while its on this evening and its well within this 8.9mm and i can see that the piston has extended foreward from the preloaded position, so i can assume that it hasnt jammed up, and it is pushing against the ideler pulley after pulling the pin.

Thats the method I use, although I used a small allen key as it's easier to pull out. Sounds like yours OK.

[davemaxx]

thanks for your quick response bushwaker, i was worried about that, i did take some measurements of the slack when cold so i will asume all is ok and have another look in a month or so, just to make sure there are no changes. i used a piece of allan key as well, i was just using the word pin as a general term so no one thought the plunger was ajustable (wound in or out). you've put my mind at rest, i think.

i am confident the cam belt isnt backlashing or will jump a tooth or get mangelled because it tightens straightaway on initial start up, it dosn't loose its center and there are no wobbels from anything when running. it takes quite a long time for this quater inch or so slack to happen while the engin is cooling, but "it's a new one to me though"