Many buyers of Ford vehicles want to know is the Ford 4.6 V8 a good engine? How long will a Ford 4.6 engine last? Is it true that some years of Ford vehicles with the 4.6 L V8 engine had problems with their spark plugs? If you're looking at getting a vehicle with a Ford 4.6 V8 engine we can answer all of these questions for you and let you know which model years and work well, and which vehicles with the Ford 4.6 litre V8 engine you may want to avoid.
What is Ford 4.6 L V8 Engine?
Also known as the Ford modular engine, Ford 4.6 L engine arrived on the scene in 1990 for the 1991 model year vehicles. They called it a modular engine because it shares certain parts among the engine family and because the plant where it was manufactured could easily be adapted to manufacture different versions of the engine in a short amount of time.
Ford uses these 4.6 L V8 engines in a number of different Ford, Lincoln, and Mercury vehicles. Under the name Triton these engines were used in Ford trucks from 1997 until 2010. In Lincoln vehicles they were called InTech engines. They came in a variety of displacements including 6.8 litre, 5.8 litre, 5.4 L, 5.3 L, and 5.0 litre, the 4.6 litre engine may be one of the most famous.
Ford invested $4 billion dollars in designing this engine. It premiered in the 1991 Lincoln Town Car. At 4.6 L it generated more power than the previous 5.0 litre V8 engine and could get the Town Car from 0 to 60 miles per an hour 1.5 seconds faster than the older engine. And it offered better fuel efficiency. It even weighed 20 pounds less than the 5.0 L engine.
The Ford 4.6 V8 was the engine of choice for many police forces around the country. They would be installed in Crown Victorias and police would keep them for about 130,000 miles. They would then be converted into taxicabs and get up to about 300,000 miles to 400,000 miles before they were finally retired. Clearly, the Ford 4.6 engine was designed to last for the long haul.
Is the Ford 4.6 V8 a Good Engine?
Although Ford has a long track record of making reliable vehicles they are not without their faults. The 4.6 engine was extremely impressive Innovation when it was created in the early 1990s. As we said it was lighter, more powerful, and more fuel efficient. But it did have some issues for a number of drivers.
The Ford 4.6 engine came with a plastic intake manifold from the 1996 until 2001 model years. Even though this was designed to handle the high temperature that an intake manifold will be exposed to, over years of use the plastic was subject to extreme Heating and then cooling over and over again. When you heat anything it expands, and then it will contract again as it cools. Over time this caused some serious damage to the intake manifold. These combined problems, the heat issue and the alternator bracket mounted in place, cause the intake manifolds to break and split often with no warning signs ahead of time. The manifold breaks either at the front or at the rear.
Another problem with this plastic intake manifold was that the alternator bracket mounted right on the plastic itself. That put even more pressure on the plastic that it was not able to handle with the constant expansion and contraction of the plastic wood exposed to heat.
So how did all of this affect the 4.6 engine? Ford 4.6 intake manifold gaskets were extremely prone to leaking. Some have argued that it wasn't a simple matter of random chance or problems, but it was a distinct and clear design flaw in the way Ford designed the 4.6 engine.
The Aluminum Manifold Fix
In 2001 Ford, recognizing the problem with their intake manifold, began replacing the plastic ones with new aluminum manifolds. They also redesign the thermostat mount. Older models of course still have the plastic manifold installed, so those would likely need to be fixed if you were going to get one. The cost of replacing an entire intake manifold in a vehicle usually runs between $400 and $600.
Other Problems with Ford 4.6 Engine
The plastic manifold issue was the biggest problem with Ford 4.6 engines, but it wasn't the only problem that drivers reported using these engines. And there were a handful of other issues that have popped up from time to time as well that are worth remembering if you are going to pick up a Ford that has one of these engines under the hood.
The timing chain in the Ford 4.6 engine is fairly long. The tensioners on it are plastic guides for whatever reason. If you kept your engine in good working order and remember to replace the oil on a regular basis, then overheating wouldn't be an issue. However, if you missed an oil change or two or use lower quality oil there could have been a problem. Also, if you use the filter that didn't have it anti drain back valve installed. These plastic guides were susceptible to wearing out and breaking down much quicker than normal as a result which ended up causing the timing chain to fail.
The Ford 4.6 engine also had an issue with a pressurized coolant leak. This was caused by the fitting for the heater hose at the back coming loose and feeling. There is also a problem on the other side with the coolant temperature sensor failing as well. Either one of these could have led to a leak of the pressurized coolant and end up causing the entire engine to overheat. These leaks weren't always very noticeable and could have just been minor but building up over time would have led to the same problem with the engine overheating.
The cam phasers in the 3-valve 4.6 engines had a problem with excessive noise at times as well. Engine knock was common for many drivers, although it wasn't extremely loud it was persistent. This happened at idle. Ford claimed that these sounds were to be expected and part of the normal operating process of the engine however many drivers still felt them to be bothersome.
If the noise happened excessively under 1,200 RPM or there was also a cam related fault code on an OBD2 scanner it was very likely an issue with a bad variable cam timing phaser that needed to be replaced. This could end up being a very costly repair with drivers having to pay anywhere from $1,500 to $2,500 to get this fixed.
Serpentine Belt Idler Pulley
In some models of the Ford Mustang, Expedition, Explorer, and F-150 there were issues with a whistling sound following a cold start. This was traced to a problem with the serpentine belt idler pulley. Ford issued a technical service bulletins related to this that recommended replacing the groove nylon front and accessory drive pulley with a new one.
Spark Plug Problems in the Ford 4.6 Engine
In several engines that were designed through the mid-2000s there was a problem changing spark plugs in the 4.6 Ford engines. This affected Mustangs, Explorers, Sport Tracks, and Mountaineers among others. The issue was that when removing the spark plug corrosion on the outer portion of the ground electrode as well as carbon buildup could end up basically sealing the plug in place. When trying to remove it there was a great risk of breaking the ground electrode where it joined the upper portion of the spark plug. That meant the metal tip of the plug and the electrode remained in the head even though the top of the plug would come out.
It wasn't impossible to remove the broken plug but Ford recommended the use of something called a Rotunda tool 303 – 1203 to extract the broken plug and odds are most drivers don't have one of those in their toolbox, and wouldn't be able to pick it out of the lineup either.
The problem was so bad that Ford dealerships were extremely reluctant to even change spark plugs themselves and in some cases were charging huge fees for drivers to get it done. There were reports of spark plug changing fees topping $1,000.
There were some tips on how to remove the spark plugs, but they definitely represent an inconvenience over what it would have taken to replace the spark plugs in any different engine. For instance, it was recommended that the plugs be changed at around 30,000 miles at most, and also that you run a combustion chamber cleaner through the engine before changing the plugs to help loosen any carbon build-up making it easier to take them out. The use of a penetrating oil spray on the plugs would help as well. And of course, all of that works and makes it easier to get the plugs out, but they are extra steps the drivers of vehicles using different engines typically don't have to go through.
Fortunately, there were aftermarket spark plugs that were made in one piece rather than the two piece ones that Ford used, that did the job just as well and fit in this engine so that changing the spark plugs didn't have to be this much of a hassle every single time.
The Ford 4.6 Engine Lawsuit
Back in the year 2005 Ford settled a class action lawsuit that was brought against them related to the use of these faulty plastic intake manifolds. Ford was held liable for over $100 million in replacement cost related to these manifolds. According to a lawyer for the plaintiffs there was a substantial engineering failure that rendered cars inoperable and often caused severe expensive damage to the engine.
Under the terms of a lawsuit anyone who had already paid to replace the manifold would get reimbursed for the cost and labour if they sought a refund from Ford by the year 2006. Everyone else got a retroactive warranty extension as well. What that means today, in the year 2020, is that if you were to buy an old Ford, Mercury, or Lincoln that had the 4.6 engine in it with a plastic intake manifold you're pretty much out of luck. If you're looking at an old model to buy, make sure it's already had the manifold replaced otherwise the cost of getting it repaired is going to be directly on you. These cars are well out of warranty at this point, so Ford will do nothing about it even though it's obviously a known issue.
The Bottom Line
So, to answer the question is the Ford 4.6 V8 a good engine, it's a bit of a yes and no. As you can see there were some clear issues with older models of the 4.6 Ford engine, but they did replace those plastic manifolds in newer models to make that a non-issue. And remember, Ford foot's millions of vehicles on the road every single year. This issue affected a number of them, but not such a huge amount that it shows make you want to avoid the engine all together
If you're looking at an older Ford, make sure you know exactly which kind of engine is in the vehicle and whether or not the manifold issue has been taken care of. Pay attention to the spark plugs as well, and the coolant sensor. Your best bet is to always get a licensed mechanic to look over any vehicle you're interested in before committing to it. Some of these Ford 4.6 engines are almost completely problem-free, and as we've seen others can definitely leave you in a position where you're going to have to be paying a significant amount of money to a mechanic if you're not careful.