Replacing the Serpentine Belt on a 2007 Ford Expedition
The 2007 Ford Expedition uses a 5.4L Triton V8, and routing that belt can be a bit of a pain if you've never done it before. I'm going to walk you through what you're looking at, how to get the old one off, and where the new one goes. There's a lot of forum posts that overcomplicate this, but it's really straightforward once you see the pattern. Here's the routing. The belt starts at the crankshaft pulley at the bottom center of the engine. From there it runs up the left side (driver's side) to the power steering pump, then across to the alternator on the right side. From the alternator it drops down to the A/C compressor, then back across to the idler pulley, and finally up to the tensioner before returning to the crank. If you're looking at the engine from the front, it basically snakes in a figure-eight pattern around the accessories. The tensioner is the one with the spring-loaded arm and a 15mm bolt in the center — that's where you apply pressure to loosen the belt for removal. I want to be clear about something that isn't obvious from any diagram. The 2007 Expedition's tensioner is mounted on the driver's side of the engine, and it's positioned right behind the coolant overflow tank. You have to remove that reservoir to get proper angle on your breaker bar. I learned this the hard way on my first attempt — I bought the belt, jacked up the tensioner with a 3/8 ratchet, and realized I couldn't get enough leverage because the plastic tank was in the way. Took about twenty minutes to unbolt the overflow, set it aside, and get the tensioner fully released. Don't skip that step.
The belt itself is a Gates 5550XS or the Ford OEM equivalent, part number FT5550. It's a 6-groove belt, about 106 inches in circumference. If you pick up a cheaper aftermarket belt from the auto parts store, be aware that some of the budget brands use slightly different groove profiles and may not seat correctly on the A/C compressor pulley. I had one where the belt would squeal under load because the inner grooves were about a millimeter wider than spec. Swapped it for a Gates and the noise was gone immediately. Stick with name brand for this one. When you're routing the new belt, start at the crankshaft and follow the path clockwise. Get it on the crank, then the power steering pump, then the alternator, then the A/C compressor, then the idler, and finally loop it around the tensioner last. The tensioner should naturally push the belt tight once you release the lock. Do not try to force the belt over the tensioner pulley — that's how you bend the tensioner arm or crack the pulley hub. Use a proper 3/8 or 1/2 drive ratchet on the tensioner bolt, pull counter-clockwise to relieve tension, slide the belt on, and let the tensioner take up the slack slowly. One thing people miss: after you install the belt, you should manually rotate the engine two full revolutions using a socket on the crankshaft bolt. This seats the belt properly in all the grooves and reveals any routing mistakes before you start the engine. I've seen people skip this, start the motor, and then hear that horrible squealing-or-slapping sound that means the belt's on wrong. At that point you're back to square one, and you've wasted time you could have saved in thirty seconds.
The tensioner on these engines tends to fail around 90 to 110 thousand miles. The bearing gets noisy — you'll hear a grinding or whining sound that gets louder with RPM. Replacing just the belt when the tensioner is already making noise is a mistake. The new belt will follow the worn bearing's imperfections and you'll be doing this job again in a few thousand miles. The tensioner assembly itself is about sixty dollars at a parts store, and the job takes another twenty minutes on top of the belt change. It's not worth saving that money. If you need a visual reference while you're working, I'd recommend pulling up the diagram on your phone rather than printing it out. Your hands will be greasy, and paper diagrams don't survive under the hood. There are a few reliable sources online — the Ford service database at all-data.ru has the official routing, and RockAuto's diagram section shows the belt path clearly. Just make sure the year and engine match your truck. Some 2007 Expeditions came with the 4.6L V8 in certain markets, and that one has a completely different routing. The whole job, assuming you have the right tools and a decent light source, takes about forty-five minutes to an hour for a first-timer. Experienced hands can do it in twenty. The tricky parts are the coolant overflow removal and making sure you route through the A/C compressor correctly — that's the groove that catches people most often. Double-check that one before you torque anything back down.
Get the Full Details
