Missing a tensioner for the AC drive belt? Just

Removing the AC pump and power steering pump from a 1999 Isuzu Trooper 3.5L can be a complex and time-consuming process. It is recommended that this procedure be performed by a qualified mechanic. However, if you would like to attempt it yourself, the following are general steps to follow:

1. Disconnect the negative battery cable.
2. Remove the serpentine belt by using a breaker bar or ratchet on the tensioner pulley to relieve the tension on the belt. Then, slide the belt off the pulleys.
3. Remove the bolts that secure the AC pump and power steering pump to the engine block. The AC pump and power steering pump share some bolts, so be sure to keep track of which bolts belong to which pump.
4. Disconnect the electrical connectors and hoses from the AC pump and power steering pump. The electrical connectors may require you to depress a tab or pull up on a locking tab before disconnecting.
5. Remove the bolts that secure the AC pump and power steering pump to their respective mounting brackets.
6. Carefully lift the AC pump and power steering pump out of the engine compartment.
7. If you plan to reinstall the AC pump and power steering pump, transfer any necessary components or brackets from the old pumps to the new pumps.
8. Install the new pumps in reverse order, using the bolts and connectors you removed from the old pumps.
9. Reinstall the serpentine belt, making sure it is properly routed around all the pulleys.
10. Reconnect the negative battery cable.
11. Start the engine and check for proper operation of the AC and power steering systems.

step one remove battery neg lug .
the above video (of book?) is wrong.
the belt tension-ing step was skipped.

remove belt steps remove alt. wiring. remove alternator (bolts) it falls free. replace it , reverse steps above belt back tension belt. battery cable back. test run. charge/BAT lamp off?
see wrench below, turn it CW.
this releases the spring tension and belt comes off
to put back, do same and put on belt and release wrench.

3.5L only. USA only.

start from bottom crankshaft pulley and ac compressor turn belt tensioner counterclockwise or lift forward then run pulley belt around crankshaft pulley and around AC compressor,run pulley belt around power steering pump then around alternator,once drive belt around alternator you done make sure drive is center of crankshaft pulley and AC compressor pulley.and belt back is center against water pump pulley before releasing the belt tensioner.

maybe if belt will route rite without rubbing . then you may have no option.

The 1st thing I'd do is to get a spray bottle with water in it and spray the belt driving the compressor while the A/C is running and cycling on and off. If this quiets the squeal, it's probably too little belt tension. Check the belt driving the A/C compressor pump for sufficient tension. Do this by locating the longest part of the belt not touching a pulley. Depress the belt at the midpoint of this open span with moderate thumb pressure. It should not deflect more than about 1/2 inch. If it does deflect more, you'll need to increase the belt tension by putting more pressure on the belt route. Usually, there's some sort of bolt or machine screw on the compressor to do this. Increase the belt tension to the desired deflection. Warning - too much tension will cause premature failure of the compressor bearing!
No improvement to the squealing requires more help than I can provide you with.

One way you can usually tell is that the tensioner base mounts to engine with a bolt in the center of the casting, & pulley is offset from that casting. Put your wrench on the offset pulley bolt to relieve tension. There are various set-ups on that engine so maybe we better confirm which engine it is ?

First, if you're serious about car repair, get the shop manual (helminc.com). Not cheap, but cheaper than ruining your engine.

Second, unless you are confident in your mechanical abilities and / or are willing to use your vehicle as training, leave major work to the pros. A good mechanic is like gold, and just as hard to find.

Third, you don't really adjust the tension. There is a spring-loaded idler that puts just the right amount of tension on the belt. Using the proper tool, you lever the idler to take the tension out and slip the belt off the other pullies. Then take the new belt and rout it just like the old one, lever the idler again, then slowly release it back against the belt to take out the slack.

Piece of cake...

It sound like you have a timing belt tensioner that is bad. Is the noise at the front of engine? If it is replace tensioner,timing belt and water pump. The pump is driven by the timing belt.

I had the same problem when trying to replace the serpentine belt on my 2001 Trooper. The Maintenance book was very vague and I couldn't tell exactly how the tension was taken off the belt, but it did clearly identify the tensioner pulley. I first removed the pulley and looked for some kind of slot that would give me the adjustment I needed, but no slotted adjustment is present on the 01 Trooper. I had to do some research so I pulled of the tensioner assembly and found that there is a spring coil which keeps tension on the belt constant, and eliminates any belt alignment problems.

The Litens style tensioner uses a spring to apply pressure towards the serpentine belt. The way to relax the spring is to use your 14mm socket and ratchet and force the pulley down by driving the pulley nut in the clockwise direction. This forces the spring to compress and the pulley to drop giving the needed clearance to get your new belt in place.

tensioner usually has a bolt in the center of the pulley wheel that is 17 to 19mm. use a breaker bar and socket to hold pulley back (sometimes has a lock that you can engage) then you can move the belt into and out of the pulleys.
have the new belt ready after you pull the old one, put it around all BUT the tensioner pulley and it will be MUCH easier to put on if you are by yourself>