Cant figure out how to loosen up the tensioner to replace serpentine belt

there should be a belt tensioner you can loosen off. loosen it, feed your belt through then tighten up the tensioner. note - get a diagram off how to feed your belt through all the wheels.

First remove the engine plastic cover by removing the bolts that hold in. Then loosen the nuts at the front of the AC Belt and Power Steering Belt. Now use a Socket set and loosen these two belts by turning the tension adjustment bolt, Anti-Clockwise.

You have to remove the first two belts (AC & Power Steering) before reaching the Serpentine Belt.

Now loosen the nut on the front of the lowest pulley before loosening the serpentine belt.

To loosen the serpentine belt, you could either remove the metal skid plate at the bottom of the engine by turning the tension adjustment bolt, Anti-Clockwise or reach down from the top and loosen it with the socket set ( quick & easiest)

You surely can tell the tensoner pulley from the others

There should be a hole to install a ratchet to release
the tension

2.8L and 3.1L Air Pump Belt

1. Disconnect the negative battery cable.
2. Loosen the air pump.
3. Remove the worn belt.

To install:

1. Adjust the belt to specifications and tighten the pump mounting bolts.
2. Connect the negative battery cable.

2.3L Power Steering Belt

1. Disconnect the negative battery cable.
2. Loosen the adjustment bolts.
3. Remove the power steering belt from the pulley.

To install:

1. Route the belt around the pulley.
2. Adjust the belt to specifications, then tighten the adjustment bolts.
3. Connect the negative battery cable.

See Figures 6 through 15

Fig. Fig. 6: Unfasten the retaining bolts...

Fig. Fig. 7: ... then remove the serpentine belt guard

Fig. Fig. 8: ...

Fig. Fig. 9: ... then remove the serpentine belt

1. Remove the belt. Clean the accessory drive belt surfaces.

Fig. Fig. 10: Serpentine drive belt routing-2.2L engine

Fig. Fig. 11: Removal and installation of the serpentine belt-2.3L engine

Fig. Fig. 12: Serpentine belt routing-2.5L engine with and without A/C

Fig. Fig. 13: Use an 18mm box end wrench on the pulley nut to rotate the tensioner on the 3.8L engine

Fig. Fig. 14: in. breaker bar to rotate the tensioner

Fig. Fig. 15: On the 3.4L, use a box end wrench, then rotate the tensioner clockwise and remove the serpentine belt

Remove the belt guard or coolant recovery reservoir as required.

1. 1 Check to ensure the Sienna's engine is cold, then make sure the Sienna is in park, the ignition is in the off position and the key is removed from the ignition to prevent any possibility of the engine engaging during the serpentine belt replacement.
   
2. 2 Open the hood and locate the serpentine belt routing diagram sticker on the side of the engine casing. Study it for a moment before removing the existing belt. It is essential the new belt be installed exactly as the diagram indicates.
   
3. 3 Find the tensioner pulley, the main pulley that controls the serpentine belt, and fit a 1/2-inch socket wrench over the self-tensioner on the outside of the pulley.
   
4. 4 Pull the wrench to the left to move the pulley forward, which loosens the belt, then remove the belt.
   
5. 5 Compare the old serpentine belt with the new, replacement belt for length, width and number of grooves on the belt's underside. Be certain the replacement belt is the right part.
   
6. 6 Fit the new belt on to each pulley according to the serpentine belt routing diagram on the manufacturer's sticker, or according to the drawing made prior to removing the old belt. Fit the new belt on to the tensioner pulley last, again applying pressure on the pulley's self-tensioner with the half-inch socket wrench to loosen the pulley.
   
7. 7 Release the pressure on the self tensioner and allow the tensioner pulley to ease back into place, thereby tightening the new serpentine belt with the appropriate tension.
   
8. 8 Remove the wrench and close the hood.
   

Thank you and good luck,
Lee

put belt on all pullys excpt water pump do it last

ther should a 1/2 " square on the the pully where u can put a ratchet in relieve tension on the belt

Then you don't take anything off. There will be a spring loaded idler that tensions the serpentine belt. Take a socket or long 12 point wrench and attach to the center bolt of the tensioner, then rotate the idler wheel away from the belt, take the belt off. Slowly release the spring tension of the idler.
The 2nd belt should be set up the same way.

If you look at the spring tensioner on the belt, there is a 3/8 square hole in the support arm.
Use a ratchet wrench, or breaker bar in the hole, and release the tension. Once it's loose, you can remove the belt.

loosen the tension pully