Does anyone have a diagram of the serpentine belt drive? Mine is slipping one rib and I think it might be the tensioner. Is the tensioner/idler the same thing?

My first gen it was the tensioner, havent had a problem with the second gen yet.

A tensioned is spring loaded to hold the belt on the pulleys and prevent slippage, an idler just allows the belt a better angle at the surrounding pulleys, though the terms are often used interchangeably. Occasionally a tensioner will be manually adjusted, like the water pump belt on an N-14 Cummins or fan belt on some C-15 Cats, but generally they're spring loaded.

For a diagram I'd check the owners manual, or fan shroud, even google, though I'm sure somebody will post one shortly. They're nice like that.:c:

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I would also recommend picking up a service manual, usually available at local auto parts or book stores, or online. Quicker and easier to look in a book for basic info than post on a forum and hope someone with the right answer responds in a timely manner, though the forums are good for more complex questions.

The auto part store sells a tensioner/idler unit for about $70. But they also sell just the tensioner/idler pulley for about $25. Do you think I will be good if I just get the pulley?

The tensioners aren't too much money and they will make your engine a bit quieter depending on how old it is. I put a new one on mine and it quieted it down a lot under the hood. :) So much that my neighbor went and bought one for his and we swapped his out too with good results. We both got ours for 60 and 70 bucks each. Belts were 35 and 40.

His belt was slipping off the pulley almost you could see it hanging over the edge so he really needed one. The wheel is on an arm and can rotate when they become worn out causing the slippage and misalignment. It only takes a long ratchet that fits right into the tensioner arm to move it. And a 13mm socket to remove the only bolt that holds it on. It's a 10 or 15 min job.

I'd recommend replacing the whole assembly, eventually the bushing inside the tensioner will wear out and cause the pulley to go out of alignment, easier to replace the whole assembly while you're there than wait til it goes out and hope you're near a parts store that has one in stock. My $.02:c:

Awesome Thanks!:jump::jump: