Opinion on serpentine belt: how much tension?

flatlander · #1 10-11-2010, 07:51 PM

While putting on the main serpentine belt (4.4 engine), I've noticed that the tension on the belt goes from zero to 'quite a bit' very quickly. The tensioner has a pretty strong force to it. Usually I look for the tension that allows me to depress The belt a half inch, but that does not seem possible on this truck. What's the recommendation on adjusting the tensioner?

meltdown325 · #2 10-12-2010, 12:01 PM

Mine is also tight as hell. The first time I tried installing a new belt I thought I had the wrong size. There just doesn't seem to be any extra slack engineered into the main belt routing on the 4.4. I use a breaker bar on the tensioner, as that is the only way I can manage to apply enough pressure to the tensioner with one hand while using the other hand to slip on the belt. Took me a while to get a technique down, but now I can get it on and off easily.

I wouldn't worry about adjusting the tensioner (I don't know if it is adjustable). Mine has been fine for the past 15k miles running super tight. I assume it's designed that way.

blktoptrvl · #3 10-12-2010, 12:44 PM

Quote:

Originally Posted by meltdown325

Mine is also tight as hell. The first time I tried installing a new belt I thought I had the wrong size. There just doesn't seem to be any extra slack engineered into the main belt routing on the 4.4. I use a breaker bar on the tensioner, as that is the only way I can manage to apply enough pressure to the tensioner with one hand while using the other hand to slip on the belt. Took me a while to get a technique down, but now I can get it on and off easily.

I wouldn't worry about adjusting the tensioner (I don't know if it is adjustable). Mine has been fine for the past 15k miles running super tight. I assume it's designed that way.

Some cars have a hole for the head of a 1/2" ratchet head to go into so you can use that as a prying point while slipping on the new belt. I am guessing from your post that the X5 4.4i does not?

flatlander · #4 10-12-2010, 01:26 PM

The 4.4 adjuster has two bolts to move the arm. The 13mm bolt sits in the slotted portion of the tensioner arm. This bolt must be loose when setting the tension. The second bolt is fixed to the tensioner arm and is 15mm. Use a 15mm socket and long socket wrench to apply the tension. Then tighten the 13mm bolt to lock it in place.

flatlander · #5 10-12-2010, 01:30 PM

See parts 7 and 8 in this diagram from

http://www.realoem.com/bmw/showparts...12&hg=11&fg=18