Routing the Belt on a 3.5L Vue
The 2008 Saturn Vue 3.5L V6 has a single serpentine belt that drives everything from the alternator to the AC compressor. It is not complicated, but it does have a specific order that matters. If you put it on wrong, the belt will just pop off immediately. I have done this swap more times than I care to count, usually at 2 AM in someone's driveway when the original belt finally gave up. Here is the routing order, starting from the crankshaft pulley at the bottom and going clockwise around the engine as you face it from the front: The belt wraps around the crankshaft pulley first, coming out from the bottom. Then it goes up and around the power steering pump pulley on the passenger side. From there it routes down to the water pump pulley, which is mounted on the front of the engine block below the power steering pump. After that it goes across to the A/C compressor pulley on the driver's side upper area. The belt then comes back down to an idler pulley located near the center of the engine. From the idler it goes up to the tensioner pulley on the passenger side, then loops around the alternator pulley on top, and finally returns to the crankshaft pulley to close the loop.
The tensioner is the key piece here. It is a spring-loaded hydraulic tensioner on the passenger side that keeps everything tight. You need a 15mm socket on a ratchet with a long extension to reach the tensioner bolt. Put the ratchet on so you can pull the tensioner toward the engine to release slack, then slide the belt off or on. It takes some force, especially if the tensioner is old and stiff. I ran into a problem on one build where the tensioner had seized from age and wouldn't release enough slack. The belt was still under heavy tension and I couldn't get it to slip off the alternator pulley. What I ended up doing was using a breaker bar instead of a standard ratchet for better leverage, and I had a helper hold the belt relaxed while I worked it. In some cases you can also use a belt routing tool from a parts store, but those tend to slip off the pulley if you don't angle them right. If you need a reference image, a lot of people pull up the diagram from sources like RockAuto or a forum PDF, but honestly the visual of the actual engine bay is faster than anything you will find online. Once you remove the old belt, take a picture with your phone before you touch anything. That saves you from having to look something up while you are holding a socket in one hand and a belt in the other.
The belt part number for the 2008 Vue 3.5L is typically a 6PK1890 or 6PK1900 depending on exactly whether your Vue has the A/C or not. The A/C-equipped models need the longer belt that reaches the compressor. Double check by comparing the old belt length, or just measure the mileage on the old one to confirm. This is one area where buying the wrong size is common, and it wastes an hour trying to make it fit. When you put the new belt on, make sure it is seated in every pulley groove before you let go of the tensioner. It is surprisingly easy to accidentally skip a groove on one pulley and then wonder why the belt sounds like it is chewing itself. Start with the crankshaft, route everything except the section over the tensioner and alternator, then apply tension and work the belt onto the last two pulleys. Check all the grooves are aligned, spin the engine by hand a couple rotations with the 15mm on the crank bolt, and verify nothing is rubbing or misaligned. The tensioner itself usually lasts between 60,000 and 90,000 miles before it starts to lose pressure. If your belt keeps slipping or making a squealing noise even after a fresh install, the tensioner is probably worn out and you should replace it at the same time. The part is not expensive, maybe $30 to $50, and it is a lot less frustrating than changing the belt three times in a year.
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