Reimagining Speed: The 4.0 V6 Mustang Story

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In 2005, Ford needed a V6 engine to bolster sales, so they chose the 4.0L Cologne V6 engine, but the motor would prove to be more trouble than it was worth.

The 4.0L (244 ci) SOHC “Cologne” V6 engine was a sixty-degree motor Ford used in its fifth-generation Mustang from 2005 - 2010. The engine produced a meager 210 hp. The engine was produced in Germany exclusively for the American market but was known to have timing chain tensioner issues.

As Ford readied the fifth generation Mustang in 2005, the company knew it needed to replace the wimpy 3.8L OHV it had used for over ten years. With the Camaro discontinued in 2002, Ford found its sales slumping despite the lack of competition in the sports car market. With most reviewers remarking that the current Mustang was ten years old and growing stale, Ford decided to upgrade the car and the V6 engine simultaneously. Ford turned to its existing 4.0L Cologne V6 (used in the Explorer, Ranger, and Mercury Mountaineer) to save money. Unfortunately, the decision would be flawed and expensive for Ford in the long run. Let’s look at the 4.0 V6 Mustang story to see how Ford Mustang owners wished for better but got less.

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The Ford 4.0L V6 Story

Ford’s use of the manufacturing plant in Cologne started nearly forty years before the introduction of the 4.0L V6. Initially, Ford used the Cologne assembly plant to produce engines for the German and British markets. Still, before long, it found itself importing engines for various compact pickups and SUVs, like the Ranger and Explorer. By the time 2005 rolled around, Ford had been using the foreign-made engine for over three decades in models like the Pinto, Mustang II, and Mercury Capri, among others. Since the relationship had already been established, having the folks from Cologne make their new 4.0L V6 made sense.

Ford heralded the new model and standard V6 engine as better than any previous engine used before. The Ford sales brochure stated that the very strong engine was “inherently more smooth and powerful than the previous V6 engine it replaced” (which was true, but the performance was only 20 hp better).

Ford spent tons of money pushing its GT model with a 4.6L modular V8, but Americans were drawn to the lower price of the V6 as more than 70,827k hardtops and 28,793k convertibles were sold with the engine. Production statistics show that the number of GT models was about half that of V6 models.

The Performance Of The 4.0L V6

In fairness, Ford applauded the engine as reliable and robust with strong engine components, and owners began to have fun driving the Mustang again. The new V6 engine produced 210 hp and 240 bl-ft of torque. When Car and Driver tested the new V6 on the track, it clocked a 6.9 second 0 - 60 mph time and a 15.3 second quarter mile. The top speed was only 113 mph, and the review complained about soft tires and poor steering, but still, the magazine declared that the V6 Mustang was a compelling package, with retro-good looks, power a plenty, and a reasonable price.” Other reviews were also very positive, including Motorweek's declaration that the Mustang is a galloping tonic that screams, ‘Loosen Up America!’” For all intents and purposes, it seemed as if the muscle car was back and running strong.

Ford would continue to use the Cologne V6 in their Mustangs until 2010, although it would keep slapping it in the Ranger for a couple more years. The engine was replaced by the 3.7L all-aluminum DOHC engine with Ti-VCT that produced 305 hp and got 31 mpg.

The Features Of The 4.0L V6 Engines

The standard engine in the 2005 Mustang was the 4.0L Cologne V6. Unlike the pushrod 3.8 V6 in 2004, this was a sixty-degree engine plucked from the Ford Explorer. While using a bona fide truck engine in a sports car might not make sense, Ford did it to save money and streamline production when they desperately needed ways to generate cash. The stock 4.0L V6 used a cast iron block for rigidity (the 4.6L V8 block was aluminum) and aluminum heads. Ford knew a SOHC engine would increase airflow, create a higher rpm redline, and improve low-end torque. Many reviewers remarked on how well the engine accelerated, which Ford was banking on when it decided to put the larger displacement engine in its pony car.

The bore for the engine was 3.94 inches, with a stroke of 3.31 inches. The steel-forged connecting rods were solid, but the compression of the new engine was still only 9.4:1 (which was only slightly better than the 3.8 V6). Ford continued using a composite intake manifold with larger 46 mm intake ports. The continued use of a heavy cast iron exhaust manifold with smaller high-velocity exhaust valves helped performance.

While the Mustang engine was more responsive and substantial, it was also loud. Ford used hydraulic engine mounts to try and minimize vibrations from getting into the cabin, but the motor sounded more like a truck motor (which it was), than the highly tuned sportscar powerplant. As one reviewer suggested, “Be sure to turn up the radio because the engine sounds as refined as a slightly muffled tractor.“

Surprisingly, the 4.0L engine has decent fuel economy. Ford needed an engine that could produce decent power but didn’t create problems for owners at the pump. The 4.0L got 17 mpg in the city and 26 mpg on the highway. With a 16-gallon tank, the Mustang had a range of over 416 miles.

Were There Issues With the 4.0L Engine?

While the 4.0L V6 was a reasonably reliable engine, it wasn’t perfect. Several reported issues associated with the engine often appear in Mustang Forums.

Timing Cam Shaft - The Death Rattle

One of the primary characteristics of the 4.0L V6 was Ford’s use of three timing chains. A jackshaft was installed in the location where the camshaft would have been and was used to drive the camshafts for the left and right cylinder heads. While the timing chain for the left bank was located in the front of the engine, the chain for the right side cam was situated in the rear. A third belts connected the jackshaft to the crankshaft.

The issue was not necessarily the configuration of the timing chains but the use of Teflon camshaft tensioners or guides. Due to the weak nature of these pretensioners, the guides could stretch or break causing a “death rattle” to the engine. The only way to fix the issue was to remove the whole engine for the repair, often causing massive repair bills. Even though, Ford was aware of the issue in other Cologne engines, they continued to use the motor for the 2005 Mustang. Eventually, Ford corrected the problem, but not before many Mustang owners had incurred the expensive repair.

Oil Leaks

The 4.0L V6 is notorious for developing leaks from the valve cover gaskets or rear main or front main crankshaft seals. If left unattended, the leak could create serious engine issues. Owners often found their engines running hot or excessive oil consumption between maintenance cycles.

Crankshaft And Harmonic Balancer

The harmonic balancer consists of a center hub covering the timing cover. Over time, the serpentine belt loosens and eventually creates issues as the balancer separates from the crankshaft pulley and reluctor ring. The repair is costly, and owners could often tell when their car struggled at higher rpms.

Plastic Thermostat Housing

Another weak spot for the 4.0L V6 was the plastic thermostat housing, which often would disintegrate. Most Mustang forums indicate it is not a matter of if but when the cover would fail. Owners found themselves dealing with leaking coolant and overheating engines. Ford made a metal cover once the complaints started, and several aftermarket purveyors carried it, even though it is a bit expensive.

The Specs Of The 4.0L V6 Engine

Item - 4.0L V6 Specification
Displacement 244.64 cubic inches
Cylinder Count 6
Valves 12
Block Material Cast iron
Cylinder Heads Aluminum
Horsepower 210 hp
Torque 240 lb-ft
Bore 3.94 inches
Stroke 3.31 inches
Compression Ratio 9.4:1
0 - 60 mph 6.9 seconds
Quarter Mile 15.3 seconds
Top Speed 112 mph
Mileage 17 city/26 hwy