2010 Ford Fusion Serpentine Belt Diagram: Routing and Tensioner Specs by Engine
Your 2010 Ford Fusion uses one of four serpentine belt setups. Which one depends on your engine: 2.5L four-cylinder, 2.5L Hybrid, 3.0L V6 or 3.5L V6. The belt part number, the tensioner bolt count and the release direction all change between them.
All four V6 and Hybrid tensioners on this model year mount with three bolts to the timing chain cover, not the single bolt Ford used through 2009. That bolt-count change is the fact most belt guides miss for 2010.
What engines does the 2010 Ford Fusion take, and why does it matter for the belt?
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The 2010 Fusion lineup covers four powertrains. The 2.5L Duratec four-cylinder makes 175 hp, and the 2.5L Atkinson-cycle engine in the Fusion Hybrid makes roughly 155 hp on gasoline alone.
Then the 3.0L Duratec V6, Flex Fuel capable at 240 hp, and the 3.5L Duratec V6 in the Sport trim at 263 hp.
Each engine sits in the same bay footprint, but Ford built a separate Front End Accessory Drive, or FEAD, for each one. That split runs deeper than belt length.
The 2.5L and the 3.0L use Electronic Power-Assisted Steering, EPAS: an electric motor on the rack, no hydraulic pump. The 3.5L V6 kept a traditional hydraulic power steering pump, driven off the belt.
A steering complaint on a 3.5L can be a belt problem. On a 2.5L or 3.0L, it cannot, because there is no belt-driven steering pump to slip.
Most belt diagram sites for this model year give one tensioner direction and move on. Search results for “2010 Ford Fusion serpentine belt tensioner direction” return both clockwise and counterclockwise as the answer, often from the same site on different pages.
The reason is that the direction genuinely differs by engine, and most guides do not split by engine before stating one.
There is a second trap specific to 2010. One aftermarket cross-reference tool lists BT4Z-8620-A as the 2010 3.0L V6 belt. Ford dealer catalogs disagree: several list BT4Z-8620-A as the earlier 2007-2009 part, and one titles it a power steering belt, which only exists on the 3.5L. Ford’s current 3.0L catalog listing is GB5Z-8620-A. We could not resolve which application BT4Z-8620-A genuinely covers on a 2010 Fusion from published catalogs alone, so if you find that number on your old belt, confirm against your VIN before ordering its replacement.
2010 Ford Fusion serpentine belt chart: part numbers, routing and tensioner specs by engine
The belt part numbers below are Ford’s own Motorcraft and OEM numbers, cross-checked against Ford dealer parts catalogs and an independent belt cross-reference. Tensioner bolt count and release procedure come from a Haynes-derived factory service manual covering this generation, read specifically for the 2010 model year.
| Engine | Belt drives | Ford belt part number | Tensioner mounting | Comes off which pulley | Mounting bolts / torque |
|---|---|---|---|---|---|
| 2.5L I4 Duratec (gas) | Alternator, A/C compressor, coolant pump. EPAS, no belt-driven steering. | 9E5Z-8620-A (2010-2012, per one dealer catalog) or AE5Z-8620-A (2010-2012, per another). See the discrepancy note below. | Two bolts to the engine block | Coolant pump pulley | 2 bolts, 25 Nm (18 lb-ft) |
| 2.5L I4 Hybrid (Atkinson) | Alternator, A/C compressor, coolant pump. EPAS. High-voltage system nearby. | AE5Z-8620-A (2010-2012, per one dealer catalog) or 9E5Z-8620-A (2010-2012, per another). | Three bolts to the timing chain cover | Tensioner pulley itself | 3 bolts, 25 Nm (18 lb-ft) |
| 3.0L V6 Duratec (Flex Fuel) | Alternator, A/C compressor on the main belt. Coolant pump on a second, tensioner-free stretch belt. | GB5Z-8620-A per Ford’s current catalog. Water pump belt: 9L8Z-8620-A. See the BT4Z-8620-A note above. | Three bolts to the timing chain cover | Tensioner pulley itself | 3 bolts, 25 Nm (18 lb-ft) |
| 3.5L V6 Duratec (Sport, AWD) | Alternator, A/C compressor, coolant pump, hydraulic power steering pump. | 7T4Z-8620-A (2007-2012). BT4Z-8620-A appears on some catalogs for this application too, see the note above. | Three bolts to the timing chain cover | Generator (alternator) pulley | 3 bolts, 11 Nm (97 lb-in) |
The 3.0L is the only 2010 Fusion engine with two separate belts. A main accessory drive belt, plus a dedicated water pump belt that has no mechanical tensioner. It is a “stretchy belt” design that self-tensions and gets removed with a strap tool, not a wrench.
The 2.5L, 2.5L Hybrid and 3.5L each run a single combined belt, with no second one listed anywhere.
How many bolts hold the 2010 tensioner, and why does that change by year?
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On four-cylinder Fusions, the tensioner bolts straight to the engine block with two bolts, unchanged across the 2006-2012 generation.
On V6 models the mounting point is different: the timing chain cover. Ford used a single bolt there through the 2009 model year. The 2010 refresh moved to three bolts, and that count held through 2012 before dropping to two bolts on later redesigns.
A 2010 V6 tensioner bolted with only one fastener is either the wrong tensioner or a prior repair that skipped two mounting points. Confirm three bolts are present before you call the job done.
Which way does the tensioner actually turn on your engine?
All four need the right front wheel and inner splash shield out first. Screws at the front of the shield, then trim clips around the rest of it, come out with a fastener removal tool.
From there, four-cylinder engines release with a wrench on the hex feature cast into the tensioner body. V6 engines release with a 3/8 inch drive ratchet or breaker bar inserted into a square hole on the tensioner arm.
Ford’s own factory-sourced procedure does not publish a single universal direction because the four FEAD layouts are not mirror images of each other. That is exactly why generic belt sites disagree: they picked one engine’s direction and applied it to all four.
Turn the tool and watch for slack appearing within the first quarter turn. If you feel resistance building instead, you are turning the wrong way for that specific tensioner.
The 2.5L Hybrid adds a step none of the others need. Ford’s procedure calls for depowering the high-voltage system before the belt comes off, since two high-voltage connectors sit close to the tensioner.
What does a bad serpentine belt sound and feel like on a 2010 Fusion?
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Match your symptom to the likely cause before pulling parts. A few of these point at something other than the belt.
| What you notice | Most likely cause |
|---|---|
| High-pitched squeal at cold startup, fades after a few seconds | Glazed belt surface, or a weak tensioner spring losing tension overnight |
| Squeal that gets worse only when the A/C is on | Belt slipping on the A/C compressor pulley, present on all four engines |
| Chirping that changes with steering input, 3.5L V6 only | Belt slipping under power steering pump load. Not possible on the 2.5L or 3.0L |
| Steering feels heavy, or an EPAS warning shows, on a 2.5L or 3.0L | Not a belt problem. EPAS runs off an electric motor, not the belt |
| Rhythmic flapping or thumping noise at idle | Belt too loose, or the automatic tensioner has lost spring rate |
| Battery warning light plus dimming headlights | Belt slipping on the alternator pulley, or a snapped belt |
| Sudden overheating warning, no visible coolant loss, 2.5L or Hybrid | Snapped main belt. The coolant pump rides the same belt on these two engines |
| Overheating with the main belt intact, 3.0L only | Check the separate stretchy water pump belt, not the main accessory belt |
| Cracking across the ribs, more than a few per inch | Belt is past service life. Flex a rib to check, glazing hides cracks visually |
Does the 2010 Fusion have a belt-driven power steering pump?
Only on the 3.5L V6 Sport. Ford’s parts catalog lists a hydraulic power steering pump assembly for the 2010-2012 Fusion 3.5L, driven directly off the serpentine belt.
No equivalent hydraulic pump exists on the 2010 3.0L. Ford’s factory documentation files the 3.0L’s steering system under EPAS, the same electric-rack system as the 2.5L, starting with this 2010 refresh.
That is a real change from the Fusion’s first model years. A 3.0L V6 sold 2006 through 2009 used a belt-driven hydraulic pump instead. The 2010 model year is the first to move that engine to EPAS.
If your Fusion is a 3.0L, do not chase a steering noise into the belt. There is no steering pump on it to slip.
Which belt part number is correct for the 2.5L, 9E5Z-8620-A or AE5Z-8620-A?
Ford’s own dealer parts network is not fully consistent with itself here, and that held true when we checked it independently for 2010 specifically, not just for later model years in this generation.
One dealer catalog lists AE5Z-8620-A as the gas 2.5L belt and 9E5Z-8620-A as the Hybrid belt. Another major Ford parts retailer lists the assignment the opposite way for the same 2010 model year.
Both part numbers are genuine Ford numbers covering the 2010-2012 2.5L engine family, gas and Hybrid combined. Which one is correct for your specific Fusion cannot be resolved from published catalogs alone.
Have the parts counter confirm against your VIN before you order either one. That beats trusting either catalog’s category label.
Tools and parts for a 2010 Fusion belt job
Owners on the four-cylinder engines commonly report a 15mm socket fits the tensioner’s hex feature. That is field-reported, not a published factory spec, so bring a small set and check what actually engages.
A dedicated serpentine belt tool kit gives you leverage a standard ratchet often cannot manage this close to the frame rail.
For the tensioner’s mounting bolts, torque them to the exact spec in the chart above rather than guessing. A small-scale torque wrench matters more here than on most under-hood bolts.
The 3.5L spec is less than half the other three. Overtightening it risks cracking the mounting boss.
Chasing a steering noise on the 3.5L specifically? Our Ford Fusion power steering assist fault reset guide covers the warning message this system throws on a real fault. That is separate from a belt-driven pump slipping.
Quick reference: 2010 Ford Fusion serpentine belt
| Engine | Tensioner mounting | Belt part number | Power steering on belt? |
|---|---|---|---|
| 2.5L I4 (gas) | 2 bolts, engine block | 9E5Z-8620-A or AE5Z-8620-A, see discrepancy note | No, EPAS |
| 2.5L I4 Hybrid | 3 bolts, timing chain cover | AE5Z-8620-A or 9E5Z-8620-A, see discrepancy note | No, EPAS |
| 3.0L V6 | 3 bolts, timing chain cover | GB5Z-8620-A + 9L8Z-8620-A (2nd belt). BT4Z-8620-A disputed, see note | No, EPAS since this 2010 refresh |
| 3.5L V6 | 3 bolts, timing chain cover | 7T4Z-8620-A. BT4Z-8620-A disputed, see note | Yes, hydraulic |
Have a different model year in this generation? The 2011 Ford Fusion serpentine belt diagram covers the year right after this one, with the same bolt-count pattern.
The 2012 Ford Fusion fuse box diagram covers the electrical side of this generation. While the hood is already up, check our 2011 Ford Fusion fuse box diagram too if you are working across model years.
