Ford 4.6L 2/3/4-valve V8 Engine: Specs, Problems, and Reliability. The Ford 4.6 L V8 engine, the first member of Ford’s Modular overhead camshaft engine family in the production, was presented in the 1991 Lincoln Town Car. It was a 4.6-liter 90-degree V-angle eight-cylinder gasoline engine with two valves per cylinder and SOHC design. Later, this engine became the base V8 in the Mustang GT. Ford also has been produced a 4-valve DOHC version popular by SVT Cobra and Mach 1 applications. This 32-valve DOHC 4.6 L engine debuted in the 1993 Lincoln Mark VIII under name of 4.6 L Four-Cam V8. The new Modular 4.6-liter V8 series replaced its pushrod-based predecessor – Ford’s Small Block 5.0 H.O. engine.
Ford’s 4.6 L V8 has a deep-skirt aluminum or cast iron cylinder block (Romeo and Windsor castings), depending on model year and application. While Windsor iron blocks have “W” letter and dowel pins at the cross-bolted main caps, Romeo 4.6 iron blocks have jackscrew cross-bolted main caps and are identified by “R” (but not every one of them). Otherwise, they look the same. Aluminum cylinder blocks were cast at the Windsor Aluminum Plant (WAP) by the exception of older 90s Teksid blocks, which were cast in Turin, Italy. Aluminum blocks came with 6-bolt main bearing caps.
Ford 4.6L 2/3/4-valve V8 Engine: Specs, Problems, and Reliability
The angle between cylinder banks is 90 degrees. Deck height is 8.937 in (227.0 mm), and cylinder bore spacing measures 3.937 in (100.0 mm). The engine block features a nearly 1:1 bore-to-stroke ratio (square configuration) that favorably affecting on its vibration, harshness, and noise characteristics. Connecting rod length is 5.933 in (150.7 mm). Modular engines were equipped with six- or eight-bolt crankshafts. Eight-bolt steel crankshaft was used in truck and high-performance applications, while six-bolt crankshafts usually were fitted in Romeo blocks under the hoods of passenger cars. All engines came with forged pistons and cracked powdered metal connecting rods from the factory.
The 4.6 engine could be fitted with three types of aluminum cylinder heads: 2- valve (1990-2014) and 3-valve (2005-2010) with single overhead camshaft (SOHC) valvetrain and 4-valve with dual-overhead-camshaft configuration. Single camshafts, along with individual intake and exhaust camshafts in the four-valve version, are driven by two timing chains (by one for each and every head). Valvetrain for every one of them features low-friction roller rocker arms and hydraulic lash adjusters. The 3-valve cylinder head features apex-shaped combustion chambers with a centralized spark plug, two intake valves, and one large exhaust valve designed to improve velocity and volume. 4.6 3V SOHC engines also were equipped with Ford’s variable camshaft timing (VCT) system. Ford 4.6 2v/3v engines feature the intake manifold constructed from composite material.
Ford 4.6L 2/3/4-valve V8 Engine: Specs
|Manufacturer||Romeo Engine Plant in Romeo, Michigan;
Windsor Engine Plant in Windsor, Ontario;
Essex Engine Plant in Windsor, Ontario
|Cylinder block material||Aluminum, Cast iron|
|Cylinder head material||Aluminum|
|Fuel system||Sequential multi-port fuel injection|
|Number of cylinders||8|
|Valves per cylinder||2/3/4|
|Bore, mm||90.2 mm (3.55 in)|
|Stroke, mm||90.0 mm (3.54 in)|
|Displacement, cc||4,601 cc (280.8 cu in)|
|Type of internal combustion engine||Four-stroke, naturally aspirated/supercharged|
|Compression Ratio||9.0:1 – 1990-2000 SOHC 2-valve engine;
9.375:1 – 2000+ SOHC 2-valve engine;
9.8:1 – SOHC 3-valve engine;
9.85:1 – 1996-1998
|Power, hp||190-260 hp (142-194 kW)/4,400-4,750 – 2-valve SOHC;
292-315 hp (218-235 kW) – 3-valve SOHC;
280-390 hp (209-291 kW) – 4-valve DOHC
|Torque, lb ft||260-302 ft-lb (353-409 Nm)/3,250-4,000 – 2-valve SOHC;
315-325 ft-lb (427-441 Nm) – 3-valve SOHC;
265-452 ft-lb (359-613 Nm) – 4-valve DOHC
|Engine oil weight||SAE 5W-20|
|Engine oil capacity, liter||5.7 l (6.0qts) with oil filter|
|Oil change interval, mile||5,000 (10,000 km)/6 months|
|Applications||the 4.6 2V: Lincoln Town Car (Touring Sedan), Ford F-Series, Ford E-Series, Ford Mustang GT, Ford Crown Victoria, Ford Thunderbird, Ford Explorer, Mercury Mountaineer, Mercury Grand Marquis, Mercury Cougar, MG ZT 260, Rover 75 V8, Mobility Ventures MV-1.
4.6 3V: Ford Mustang GT, Ford Mustang Bullitt, Ford Explorer Sport Trac, Ford Explorer, Ford F-Series, Mercury Mountaineer.
4.6 4V: Ford Mustang SVT Cobra, Ford Mustang Mach 1, Lincoln Mark VIII, Lincoln Continental, Lincoln Aviator, Mercury Marauder, Marcos Mantis (GT), Panoz AIV Roadster, Panoz Esperante, MG X-Power SV, Koenigsegg CC8S, Koenigsegg CCR V8.
All 32-valve 4.6 L DOHC engines had aluminum blocks only (except 2003-2004SVT Cobra, which had an iron block with 4-bolt main bearing caps). Each cylinder has two intake and two exhaust valves. The 1993-1998 four-valve heads feature individual intake port for each and every intake valve (split-port design). In 1999, cylinder heads were revised, and engineers implemented tumble-style intake ports where one intake port feeds two intake valves. In that year, they also replaced the variable runner-length intake manifold by a fixed runner-length intake manifold and changed camshaft profiles.
Modular 4.6 L V8s had a traditional sequential multi-port fuel injection system controlled by ECU and mechanical/electronic throttle body. They also fitted with an electronically controlled, individual coil-on-plug ignition system.
The 4.6-liter 4-valve V8 engine featured on Ward’s 10 Best Engines List for 1996 and 1997 years, while the 3-valve version got on the list for 2005-2008 and received a variety of accolades. Using this engine as a base, Ford developed a bigger 5.4-liter engine series, which also gained good success in sales. The production of the 4.6 L Modular engine was ceased in 2014. The last engine of free throw line was a 4.6 2v engine for a 2014 model year Ford E-Series van. Already, the new Modular 5.0 L Coyote engine, its successor, already had been produced for 3 years.
Ford 4.6 V8 Modular Engine Problems and Reliability
Ford’s Modular 4.6 V8 has gotten a highly positive reputation amongst owners in terms of reliability and longevity. The engine can easily run well over 200,000 miles. Some taxi services used Crown Victorias with 4.6 V8 until impressive 300,000 or even 400,000 miles. But of course, ideal engines do not exist, and this engine has several common problems and made flaws that currently are widely known.
The first wide-spread problem is plastic intake manifold cracking. This problem could be found in 4.6 L SOHC 2-valve engines produced from 1996 to 2001. During that period, Ford used a nylon composite intake manifold manufactured by DuPont, this manifold leaned to failure with no warning or sign. The reason is the intake manifold could not handle stress on the material triggered by thousands of heat/cool cycles (expansion and contraction) and additional forces/vibrations originating from the alternator bracket mounted right into the plastic. Therefore, this manifold can crack and split, the heater hose and coolant temperature sensor can loosen, which would result in an engine coolant leak and vehicle overheating. Late in 2001, Ford replaced the all-plastic manifold with a revised intake manifold that uses cast aluminum at the failure points.
A short thread depth in the aluminum cylinder heads is the root of the second common problem – stripping of cylinder head spark plug threads. Be careful while changing spark plugs on any Ford 4.6 V8s, as it is so easy to over-torque them and striping threads. Ford suggests a threaded insert as the method to repair stripped thread and even provides a tool kit specifically for that.