Ford Ranger 4.0L SOHC V6

Ford introduced the 4.0L SOHC (single-overhead-cam) engine in the Ranger in 2001 as a replacement for the 4.0L OHV (over-head-valve). The 4.0L SOHC engine had already been an option in the Explorer since 1997. Only the Ranger and Explorer used this engine from 2001 through 2004. In 2005, the Mustang dropped the 3.8L engine in favor of the 4.0L SOHC. These three vehicles used the 4.0L SOHC through 2010; in 2011 the Mustang and Explorer switched to newer, more powerful, engines, but the 2011 Ranger still used the 4.0L SOHC.

The Ford 4.0 V6 engine has a bore of 3.95 inches and a stroke of 3.32 inches. The bore and stroke combine to create a total engine displacement of 245 cubic inches and features a compression ratio ranging from 9:1 to 9.7:1, depending on the year and model of the car. The engine has two valves per cylinder, one intake, and one exhaust making a total valve count of 12.

Ford 4.0L SOHC Output:

The Ford Ranger 4.0L SOHC produces 207 horsepower at 5,250 rpm and 238 foot-pounds of torque at 3,000 rpm. In the Ford Explorer, the 4.0L SOHC produces 210 horsepower at 5,100 rpm and 254 foot-pounds of torque at 3,700 rpm. In the 2005 through 2010 Ford Mustang, the 4.0 produces 210 horsepower at 5,300 rpm and 240 foot-pounds of torque at 3,500 rpm.

SOHC & OHV Engine Differences:

The difference between a SOHC 4.0L and OHV 4.0L is that in a SOHC engine there is a camshaft sitting on the top of each cylinder head with the valves running directly off the camshaft. It doesn’t rely on push rods, rocker arms, or lifters. The SOHC engine uses a jackshaft in place of a camshaft to drive a timing chain to each cylinder head. Three timing chains are used, one from the crank to the jackshaft, one in the front of the engine to drive the cam for the left bank, and one on the back of the engine to drive the cam for the right bank.

The OHV engine has the cam mounted above the crank. The cam and crank are joined in time by a timing chain. Lifters ride on the cam and push rods that extend to rocker arms in the heads which push the valves.

For the 4.0L OHV engine visit:

Ford Ranger 4.0L OHV V6

Ford Ranger 4.0L SOHC Specifications:

4.0L SOHC Timing Chains:

The 4.0L SOHC has an unusual overhead cam drive setup. Unlike most other OHC V6 and V8 engines that drive both overhead cams directly from the crankshaft with a belt or chain, this engine has an intermediate jackshaft in the middle of the block where a pushrod cam would normally be located.

A short timing chain on the front of the engine connects the crankshaft to the intermediate jackshaft. A second, longer timing chain behind the first chain connects the front of the jackshaft to the overhead cam on the left side of the engine.

A third timing chain in the back of the engine connects the rear of the jackshaft to the overhead cam in the right cylinder head. There is also a balance shaft in the crankcase of engines used in 4×4 trucks, which is driven by a fourth chain directly off the crankshaft.

Why Ford designed the cam drives this way is anyone’s guess. It probably allowed the engine to be shorter and more compact. But one of the unintended consequences of this fore-and-aft split cam drive arrangement is that it makes the timing chains, guides and tensioners VERY difficult to replace — which makes for an expensive repair when a chain guide or tensioner fails on one of these engines (a common problem on high mileage engines, especially if the owner has ­neglected regular oil changes).

Balance Shaft & Balance Chain:

A balance shaft & associated balance shaft chain (see diagram below) were fitted in the 1997 thru about 2001 Ford 4.0L SOHC engines used in 4WD vehicles. They were not fitted after that, as it was determined that 4WD drivetrains did NOT induce excess vibration previously assumed. To determine if your 4.0L SOHC has a balance shaft, drain the oil, remove the oil pan and the balance shaft will be visible up thru the engine girdle next to the oil pump.

Timing Chain Problems:

Some of the early engines up through 2002 in the Ranger and Explorer have had a timing chain rattle problem due to the poor design of the original Teflon chain guides. The noise is most noticeable when a cold engine is first started and is usually loudest from 2,400 to 3,000 rpm.

The same noise problem can also develop in 2003 and newer high-mileage engines as a result of chain guide wear. In some instances, the guide may break and disintegrate and spew debris into the oil pan. This may also cause one of the timing chains to break (typically the front left chain).

Fortunately, the 4.0L SOHC is not an interference engine, so a timing chain failure won’t bend the valves. But it does create an expensive repair for the vehicle owner.

Ford issued a TSB for the timing rattle problem and released a redesigned “‘cassette”‘ (the timing chain, gears, guide and tensioner assembly) for the left front timing chain. This timing chain cassette can be replaced without having to pull the engine out of the vehicle.

But, if the engine has a bad rear chain or guide, or a chain guide has failed and throws debris into the crankcase, you will have to remove the engine to make the required repairs. That includes removing the flywheel and flexplate so that the rear cam drive cassette can be replaced and pulling the oil pan so any debris in the oil pan and oil pickup screen can be cleaned out.

You’ll also need a special tool kit (Ford or aftermarket) to hold the cams and tension the timing chains, and to prevent the crankshaft from rotating while you’re doing the cam drives. You’ll also need the proper puller to get the harmonic balancer off the crankshaft.

The redesigned Ford primary timing chain service kit includes an improved chain tensioner and chain guide, chain, jackshaft and sprockets. Kit number 2U3Z-6D256-AA is for balance shaft engines in 1999 to 2001 4×4 Explorer/Mountaineer, 2001 to 2002 4×4 Sport/Sport Trac and all 2002 Explorer/Mountaineer (except engine codes 2G-960-AA and 2G-964-AA). Kit number 2U3Z-6D256-BA is for non-balance shaft engines in 1999 to 2001 2WD Explorer/Mountaineer and 2001 to 2002 2WD Sport/Sport Trac, and all 2001 to 2002 Ranger.