The 4.6L Ford engine has been installed in millions of vehicles over the years. It is the engine of the very popular Ford Crown Victoria, Mercury Grand Marquis, and Lincoln Town Car. These engines use plastic intake manifolds and from 1996 through 2001 there was a problem that can leave drivers stranded. The problem is a sudden cracking of the intake manifold.
The Ford plastic intake problem
The plastic manifold used on these 4.6L engines tend to split across the front, and break in the rear, without warning. Often this will occur with out previous symptoms. Other times a slow coolant loss may precede the failure. When the intake fails, the engine coolant pours out, and the engine quickly overheats.
The front temperature sensor and rear heater hose connection are also prone to pulling out of the intake. Intake manifold replacement is an expensive and very inconvenient problem but Ford has never recalled the vehicles. Rather, a class action suit against the automaker was quietly settled several years ago. Ford agreed to reimburse some customers for a short while and extended the warranty to seven years from the date of purchase. The last warranty extensions ended in 2008.
Identifying the problem Ford intake
They introduced an improved intake manifold beginning on the 2002 models and this greatly reduces the chances of problems. The new intake has a cast aluminum piece across the front and a redesigned alternator mount. The new intake manifold has less stress on these key mount areas and a stronger material to support the load.
Why do the Ford intake manifolds crack?
On the original all-plastic version, Ford braced the rear of the alternator to the intake. The belt pulls heavily on the front of the alternator especially under load. Years of hot and cold cycles combined with the vibration and pull from the alternator can result in the plastic intake splitting. This allows the pressurized engine coolant to flood out, into the rear of the alternator. Repair involves replacing the old style intake with the new, replacing the coolant and sometimes the alternator. Since the intake is buried under several layers of engine components, this is no small task.
In some instances the metal threads of the engine temperature sensor and the heater hose nipple also pull out of the intake. The result is the same as with the split plastic: the coolant is loss and the vehicle is disabled.
The most common vehicles to have this problem are Ford, Lincoln and Mercury, built from 1996 through 2001 and having the 4.6 liter engine. We have also seen leakage to a much lesser degree on the later models.
Lists of Ford products, with Intake manifolds prone to splitting
Mercury Grand Marquis
Lincoln Town Car
Ford Crown Victoria
Ford Mustang (some)
If you have a Ford product with the 4.6L engine, AGCO can check it for you. This is also part of our Pre-purchase Inspection, Trip Check, and General Inspection on these vehicles. Don’t be stranded, let AGCO check your vehicle. AGCO, it’s the place to go.