The Ford 3.0L Duratec V6 engine, which has was introduced back in 1996, has Sequential Multiport Fuel Injection (SFI), a single coil distributorless ignition system, and an upper and lower intake manifold with electronically controlled Intake Manifold Runner Control (IMRC). Recent versions of this engine also have variable valve timing. The dual overhead cams on the Duratec engine are chain driven, so there is no timing belt to replace.
The Ford 3.0L Duratec V6 replaced the aging 3.8L V6 in the Ford Taurus and Mercury Sable. Unlike its conventional pushrod predecessor, the 3.0L V6 has dual overhead cams, four valves per cylinder, and an aluminum block with cast iron cylinder liners. It is essentially a larger version of the 2.5L Duratec sixty degree V6 that was introduced in the 1994 Ford Contour and Jaguar X-Type. Both engines have the same 79.5 mm stroke crankshaft, but the 3.0L engine has a larger cylinder bores (89 mm versus 82.4 mm in the 2.5L Duratec).
The 3.0L Duratec engine has its coil mounted on the front valve cover, and the firing order is 1-4-2-5-3-6. The plugs are gapped at 1.3 to 1.4 mm (0.052 to 0.56 inches)
Over the years, this engine has undergone continual evolution and has been produced in several variations, including:
* A 208 horsepower version with roller finger followers for the Taurus and Sable, and the 2001 and up Ford Escape and Mazda Tribute.
* A more powerful 232 horsepower version for the 2000 to 2005 Lincoln LS, Jaguar AJ30 and S-Type, Mazda 6 and MPV, and 2005 Ford Five Hundred, Mercury Montego and Ford Freestyle with direct acting mechanical bucket tappets.
* A Variable Valve Timing (VVT) with electronic throttle control for the 2003-2006 Lincoln LS, 2003-2006 Jaguar X-Type applications, 2006 Ford Fusion, Mercury Milan and Lincoln Zephyr, and 2009 Ford Escape. On the 2009 Fusion, a new type of VVT system called "Cam Torque Actuated" (CTA) is used to advance cam timing. The cam phaser generates its own internal pressure rather than relying on oil pump pressure to move the cams. The result is more advance (47 degrees) and better fuel economy.
Though the 3.0L Duratec V6 has had a relatively long production run, it's successor is the larger displacement 265 horsepower 3.5L Duratec V6, which powers the 2007 Ford Edge, Lincoln MKX and MKZ, and 2008 and up Taurus and Sable, and 2009 Ford Flex. An even larger 275 horsepower 3.7L Duratec V6 with a 95.5 mm bore is used in the 2008 Mazda CX-9 and Lincoln MKS, and 2009 Mazda 6. Ford says it will continue making the 3.0L V6 for several more years with additional improvements to reduce emissions and improve fuel economy.
The first generation 3.0L Duratec blocks produced from 1996 through 1998 can be identified by the "F5DE" casting number on the engine block. In 1999, Ford changed to a slightly different casting (XW4E) which has different coolant passages on the right side that require a different head gasket. Install an old style head gasket on this engine and it will leak coolant. The following year, Ford revised the block casting slightly and reduced the size of the knock sensor threads from 12 mm to 8 mm. Other than that, the 1999 and newer blocks are interchangeable. The 2000 to 2004 blocks have the casting number XW4E-BA.
The cast iron liners in the aluminum block can be bored to oversize if the cylinders are worn or tapered. Flat top pistons with a slight dome are used without valve reliefs in the older 3.0L Duratec engines that do not have variable valve timing, but pistons with four valve reliefs are required for additional valve clearance in the newer versions with VVT. The compression ratio is the same, so the newer pistons can be used in the older applications.
All Duratec engines use powder metal connecting rods with cracked (fracture-split) caps. Rod lengths and weights are all the same, and can be interchanged from one year to the next. If the big end of the rod is worn or stretched, though, the rod has to be replaced because cracked caps cannot be ground to resize the bearing opening.
The most variation in these engines is found in the cylinder heads and front timing cover. The right and left heads are different on all the engines, and are identified by different part numbers. So if you need to replace a head, make sure you get correct side.
The heads on the early 1996-1998 engines have six round intake ports and have a casting number F5DE. The 1999 model year heads (F7DE) also have six round intake ports, but the right head has a protrusion to cover an oiling port in the block (which is used in later engines to pressurize the variable valve timing system).
In 2000, the design of the heads changed significantly, going to three oval intake ports. The 2000 castings are YF1E for the right head, and YL8E for the left head.
In 2001, the heads changed again when Ford moved the water pump from the right front side of the engine (as viewed from the front) to the left side. This also required a change in the location of the serpentine belt tensioner from the left side of the timing cover to the right side (as viewed from the front).
The 2000-2001 Lincoln and Jaguar 3.0L Duratec engines use a slightly different head casting (XW4E). In 2002, the head castings numbers changed (1X4E) on these engines, but the heads appear to be identical.
The front timing cover on the 3.0L Duratec has undergone various changes to accommodate changes in the valvetrain. From 1996 to 2000, the front covers on Taurus/Sable have a fitting at the top right for the camshaft position sensor, and a fitting at the lower left next to the crank for the crank position sensor. The belt tensioner is located on the left side of the cover. In 2001, Ford changed the location of the belt tensioner from the left side of the cover to the right to facilitate the relocation of the water pump.
If you have a noisy serpentine belt on one of these engines, be sure to check the serpentine belt tensioner as a weak spring may be allowing the belt to slip. And if you replace the belt, it's a good idea to replace the tensioner too on high mileage engines.
On 2001 to 2004 Escape/Tribute engines, the crank sensor is relocated to the right side of the crank (as viewed from the front). On the 2000-2003 Lincoln/Jaguar engines, the crank sensor is to the left of the crank, and it is a different sensor with a different angled exciter ring on the crank. On the 2003-2006 Lincoln and 2003-2004 Jaguar engines with VVT, the front timing cover mounts two camshaft position sensors (one for each intake cam).
Ford has used two basic camshaft variations in the 3.0L Duratec. The early style cams were all the same from 1996 through 2000. But mid-year 2000, Ford changed from a 36-tooth cam sprocket to a 42-tooth gear. The early and late cam gears with different numbers of teeth are not interchangeable.
If you have to remove or replace a cylinder head for any reason, or replace the timing chain on a 3.0L Duratec, it can be a bit of a challenge because Ford doesn't provide a Top Dead Center (TDC) timing reference mark on the crankshaft. You have to use a dial indicator to find the TDC position of the number one cylinder to make sure the crank and camshafts are all properly aligned.
Ford says that when the crankshaft keyway is positioned at roughly the 11 o'clock position, the number one cylinder should be at TDC. Before you can remove the timing chain, the front cover has to come off the engine. Then you have to remove the crank sensor pulse wheel. Note the sensor wheel location before you remove it.
Rotating the crank until the keyway is at the 3 o'clock position will move the right cylinder head camshafts to the neutral position. The timing mark on the intake cam should be pointing to the right when viewed from the front, and the timing mark on the exhaust cam should be pointing straight up if both cams are in the correct position. You can now remove the chain tensioner arm, chain guide and right timing chain.
To remove the left timing chain, rotate the crank clockwise 600 degrees (1-2/3rds turn) to the key way is again at the 11 o'clock position. This will position the left cylinder head cams in the neutral position. This time, the timing mark on the intake cam should be pointing to the left when viewed from the front, and the mark on the exhaust cam should be pointing straight up. As before, you can now remove the chain tensioner arm, chain guide and left timing chain.
Before you can reinstall the timing chains, you need to compress the left and right chain tensioners in a vice. Compress the piston until it is fully bottomed, then temporarily lock it in place with a pin or paper clip.
If the replacement timing chain does not have timing marks for aligning with the cam gears, you'll have to mark the left and right side chains. Start with the left chain, and mark one link as the starting crankshaft timing mark. Then count 29 links and make a second mark (for the exhaust cam). Continue counting to link number 42 and make a third mark (for the intake cam). The second and third marks should align with the timing marks on the intake and exhaust cams when the chain is slipped into place. The chain tensioner and arm can now be installed.
Next, you do the same procedure for the right cam. But first, you need to rotate the crankshaft 120 degrees clockwise so the crankshaft keyway is at the 3 o'clock position. Mark the right timing chain and install it the same as before.
Once both chains are in place, remove the locking pin or paper clip from the left and right chain tensioners. Rotate the crankshaft 120 degrees counterclockwise so the keyway is back at the 11 o'clock position and number one piston is at TDC. Check to make sure all the timing marks are aligned as shown in the illustration. There should be 12 chain links between the right and left intake and exhaust cam sprocket marks, 27 chain links between the cam gears and crank on the non-tensioned side of each chain, and 30 links between the cam gears and crank on the tensioned side of each chain.
If the Check Engine light is on and you find a code P1518, it means the intake manifold runner control system has a problem. Most likely, the runner control is stuck in the open position. Sludge can build up in the IMRC causing it to stick. Ford also offers a PCM reprogramming fix in TSB 02-15-3 that causes the IMRC to cycle at speeds over 40 mph so sludge doesn't build up on the runner plates.
If you run into an engine in a 1996-1998 Taurus or Sable that cranks and has spark, but won't start, the fault may be a dead fuel pump because of shorted wiring. TSB 98-25-1 covers the installation of protective plastic tubing on the fuel pump wires to prevent chaffing on these vehicles.
Hard starting and long cranking times on 1996-1998 Taurus and Sable may be caused by bad fuel, wet spark plug wires or a sticking idle air control valve. TSB 98-21-12 covers the diagnosis of this condition, and TSB 97-9-5 covers replacing the IAC valve.
Fuel delivery problems on 1996 to 1998 Taurus or Sable 3.0L V6 can prevent the engine from starting. The engine will crank normally and will have spark, but it won't start because the engine is not getting any fuel. The problem is not a bad fuel pump, but a dead fuel pump because the wires to the pump on top of the fuel tank have shorted out. Ford TSB 98-25-1 covers the installation of protective plastic tubing on the fuel pump wires to prevent chaffing on these vehicles.
P0171 and P0174 lean codes are common faults on many Ford, including the 3.0L Duratec. The lean fuel condition is often caused by a dirty mass airflow sensor, vacuum leaks in the intake manifold or vacuum connections, or by a defective DPFE sensor. The fix may require cleaning or replacing the MAF sensor, or using a smoke machine to find elusive vacuum leaks in the intake plumbing.
If you find a 1996-2003 Taurus or Sable with a rolling idle or surge problem, poor fuel economy, or codes P1336, P1309 or P0340, the cause may be a misaligned camshaft position sensor. TSB 02-22-1 covers diagnosis of the cam sensor and aligning the cam sensor with a special installation tool.
One common problem we've seen in high mileage Taurus/Sable vehicles with the Duratec engine is coolant contamination caused by rust and corrosion in the coolant pipes that snake around the engine. This is often the result of coolant neglect. Cleaning and flushing the system can get rid of the gunk, but it won't stop the corrosion inside the steel pipes. Replacing the pipes is recommended to halt the rusting problem.
Electrolysis that eats through the heater core can also be caused by missing, loose or broken engine ground straps. You can use a volt meter to check for electrolysis in the coolant. Remove both cables from the battery, then touch the negative test lead to the negative battery post, and the positive lead to the coolant in the radiator or coolant reservoir. A reading of more than 0.4 volts indicates trouble. Check the engine ground straps. Ford says not to ground the heater core as this will make the electrolysis problem worse. Drain and refill the cooling system with new coolant.