Engine History: The Ford 4.6 liter V8

4-6 complete

Events at Ford Motor Company have been silently spelling the end for their bread-and-butter V8 of the last two decades.  With the cancellation of the Panther platform (Ford Crown Victoria, Mercury Grand Marquis, and Lincoln Town Car) and Ford’s movement to a predominantly V6 based lineup in their F-150′s, the smooth and hardworking 4.6 liter V8 is almost extinct.

The 4.6 liter engine was the replacement for the Windsor family of Ford V8′s.  Having been introduced in the 1962 Ford Fairlane as the 221 cubic inch V8, the Windsor engines would ultimately be found in many familiar sounding sizes (289, 302, and 351) and would power everything from Falcon’s to F-350′s.  It was quite a versatile engine yet it had lived its life.  It was time to move on and Ford definitely did not allow for much confusion when it created the 4.6.

The 4.6 liter V8 was the first of what was dubbed the “Modular Engines” from Ford.  Many have misinterpreted the meaning of “modular” in describing the 4.6 and 5.4 liter V8 plus the related 6.8 liter V10; “modular” was used to describe a manufacturing process, it was not a reference to parts interchangeability.  With a bore of 90.2 mm and a stroke of 90.0 mm, this engine was very nearly a square bore.  At the time of its introduction in the 1991 Lincoln Town Car, it was the only V8 produced by a United States manufacturer to have an overhead cam valve train (Update: also the limited-production Corvette ZR-1).  After roughly forty years of American consumers having lived with overhead valve V8′s the overhead cam was a distinct difference – and perhaps part of why the 4.6 is periodically a misunderstood engine.

1991 Lincoln Full Line-02

With its introduction in the ’91 Town Car, Ford was wise.  Lincoln buyers likely didn’t care what engine their car had as long as it was smooth and made good power.  The 4.6 was certainly a smooth engine and a good power plant for a 4000 pound Lincoln.  Rated at 190 horsepower that first year, the new 4.6 created forty more peak horsepower than the outgoing 5.0 liter V8.  Fuel economy was the same with an EPA rating of 15 city and 22 highway (as per current EPA methods).

1992 Mercury Grand Marquis-05

The 4.6 would be standard equipment in 1992 for the updated Ford Crown Victoria and Mercury Grand Marquis.  This engine would be the exclusive power plant for the Panther bodied cars until their demise in 2010.

http://www.automobile-catalog.com/make/ford_usa/thunderbird_10gen/thunderbird_10gen_lx/1996.html

http://www.automobile-catalog.com/make/ford_usa/thunderbird_10gen/thunderbird_10gen_lx/1996.html

As the 1990′s unfolded, the 4.6 would continue to emerge in a greater variety of Ford Motor Company products.  1994 would see the 4.6 between the fenders of the Ford Thunderbird and Mercury Cougar where it would remain an option until the temporary termination of the Thunderbird in 1997.  A 1996 Thunderbird is shown here.

www.edmunds.com

www.edmunds.com

1996 would see the 4.6 liter arrive in the Mustang GT, much to the initial chagrin of the Mustang and 5.0 liter faithful.  In its initial appearance in the Mustang, the 4.6 liter engine was rated at 215 horsepower.

http://www.edmunds.com/ford/f-250/1997/

http://www.edmunds.com/ford/f-250/1997/

1997 would see the expanded versatility of the 4.6 with its placement in the new F-150 and the E-Series vans that had been redesigned for 1992.

While the intent of this article is to focus on the 2 valve version of the 4.6, it needs to be noted there were 3 valve and 4 valve versions offered at various times.  The 4 valve version was introduced in 1993 as the InTech V8 for use in the Lincoln Continental and Mark VIII.  As initially found in the Mark VIII, it produced 280 horsepower and 285 lb-ft of torque.  The 3 valve version was first used in the 2005 Mustang and later in the ’09 F-150.  Interestingly, the 3-valve was rated at 300 horsepower in the Mustang and 292 horsepower in the F-150; both were rated at 320 lb-ft of torque.  That should be viewed as a testament to refinement and ever-expanding engine technology.

In the interest of full disclosure, this author owns or has owned four vehicles powered by the 4.6 liter V8; a 1992 Crown Victoria, a 1996 Thunderbird, a 2001 Crown Victoria, and a 2007 F-150.  These engines were anywhere from brand new (in the case of the Thunderbird) to having 140,000 miles on the ’92 at the time it was sold.

The general driving characteristics of the 4.6 were remarkably different from what most operators were accustomed.  Let’s look again at the ’91 Town Car as compared to the ’90 Town Car.  The ’91 is rated at 190 horsepower whereas the ’90 generated 150 horsepower from its 302 cubic inch (5.0 liter) V8.  However, the ’90 generated its peak horsepower at 3,200 rpm, a full 1,000 rpm lower than the ’91.  Similarly, when discussing torque, the ’90 had a 10 lb-ft advantage over the ’91; the ’90 also generated its peak torque at 2,000 rpm whereas the ’91 generated its peak at 3,200 rpm.

The author has observed several instances of people’s misperception of the capabilities of the 4.6 liter in pickup applications – where torque truly is king.  Recently, he was approached by a field employee requesting a 3/4 ton pickup.  As this employee would soon have a periodic need to pull a 4,000 pound trailer, the employee was concerned about damaging his 4.6 liter powered pickup.  Despite providing Ford’s engine rating of 248 horsepower and the towing capacity chart for ’08 F-150′s to the employee, there was still an above average level of skepticism.  A field visit to take turns pulling this trailer resulted in the employee being convinced while saying, “that’s a really small engine; it’s a lot stronger than I thought.”

As introduced in the ’97 F-150′s, the 4.6 made 220 horsepower at 4,750 rpm with maximum torque of 265 lb-ft at 4,000 rpm.  When compared to the 5.0 liter in the 1996 F-150, the 4.6 has a 21 horsepower advantage at 550 more rpm’s; torque is within 5 lb-ft at 270, but it is fully available at only 2,400 rpm.  By current measuring standards, the EPA rated the 4.6 liter in model year 1997 two-wheel drive applications as being capable of 20 mpg – 3 mpg better than the 5.0 liter V8 from 1996.

The 4.6 simply revs more to generate its power.  For many accustomed to the immediate torque of pushrod V8′s, this was a distinct difference.

While the 4.6 is a stout engine, its 20+ year production run hasn’t been free of blemishes.

www.rockauto.com

www.rockauto.com

Information on the valve guide seals is rather scattered.  From what can be gathered, the valve guide seals in the 1995 model and older 4.6 liter engines have a tendency to deteriorate prematurely.  For this engine it is a more complex than normal repair given the overhead cam drivetrain.  Repairs can be made without removal of the heads, but it does require special tools to work around the camshaft.  This repair does pose a higher degree of complexity than a similar repair on an overhead valve engine.

It is still not unusual in this part of the United States to find cars powered by early versions of the 4.6 to be blowing smoke upon acceleration.  The author’s ’92 Crown Victoria had a similar issue that burned a quart of oil approximately every 500 miles.  Posts on various message boards will have claims of twice the oil consumption in some instances.  Claims are made that this began at as little as 75,000 miles with 100,000 to 130,000 miles being the general range of the seals beginning their decline.  1996 is the general claim on when this problem was effectively corrected from the factory.

spark plug

www.steeda.com

Changing the spark plugs on the 4.6 liter V8 has been a distinct issue for some.  While the location of the plug itself is unusual – it is accessed adjacent to the intake manifold and is quite deep in the valley of the engine – the bigger concern of many is the breaking of spark plugs during removal.  Ford has even issued a technical service bulletin to address this issue.  The causes are varied yet it appears the issue revolves around two items:  the temperature of the engine during removal and the aluminum heads of the engine.

4-6 apart

Let’s take a better look at where the plugs are located.  On the left side of the picture, you can see two plastic connectors pointed straight at the spark plug holes.

Fortunately the author has not encountered this on any of the 4.6 liter engines he has owned, yet the issue is real.  Common advice found is to change the plugs only when the engine is cool and to be gentle throughout the process.  Any experiences by the commentators on this or any other challenge described is welcomed.  There is a similar issue with spark plugs on the 3 valve 4.6 liter engines due in part to the construction of the plug itself, although that is outside the focus of this article.

ford_4.6L_intake_manifold_problem

Beginning in 1996, Ford placed intake manifolds on the 4.6 liter engines constructed of a nylon composite manufactured by DuPont.  This worked well for a while.

4 6 failure

In time, many of these intake manifolds would fail in the area coolant was routed.  This picture shows a failure along the front of the manifold; various sources will show various locations of failure.  The author experienced an intake failure on the engine of his 2001 Crown Victoria Police Interceptor at 128,000 miles.  This particular failure was a crack in the thermostat housing that dumped coolant on the ground overnight after a 25 mile trip.  As Ford has classified these manifolds as a wear item, an aftermarket unit with an aluminum coolant passage was installed.

In the early 2000′s, there was a class action lawsuit brought against Ford due to the failure of these intake manifolds.  Ford did provide replacements as part of the settlement, albeit for a very short period of time.

Ford’s 4.6 liter V8 has had a few issues during its lifetime, however none of these directly relate to the overall durability of the engine.  Finding stories of 4.6 liter engines with over 300,000 miles is not hard to do; on a recent trip to Kansas City the author rode in a Crown Victoria taxi with 362,000 miles on the odometer.  These are robust engines that can often be found in very tortuous use, such as police and taxi service.

As mentioned for the Mustang, this power plant was not readily met with enthusiasm by the performance crowd.  Times have changed as the aftermarket has caught up with demand.  Further, the 4.6 is now a popular engine for transplants into other vehicles, such as Rangers and older Ford products from the 1950′s and ’60′s.

Despite the production of this engine currently being in E-Series vans only, these little power plants will continue to power current and future Curbside Classic’s of many varieties for countless years to come.

www.therangerstation.com

www.therangerstation.com