The Ford 4.6 liter V8.

[piece-it pete]

Gotta love V8s!

After 3 different 5.0s' ('84, '87, and '90) in Grand Marquis I graduated to a 4.6 in my '97 three years ago.

Great engine imo so far.

But two things I thought I'd mention, as there has got to be a number of folks on this board that have this engine in Mustangs, full size boats like mine, trucks, etc, so I thought I'd start a thread.

1st, most 4.6s' made from 95-97 have a SERIOUS FACTORY DEFECT, as in the intake manifold has an integrated pipe that moves coolant from one side of the engine to the other, that CRACKS. This includes Cougars and Tbirds as well as the abovementioned.

Bless it's corporate soul, Ford recalled all fleet vehicles (cop cars, taxis, etc) but left us lowly consumers holding the bag. Sure enough, mine cracked (you'll know it - coolant pours out like crazy from behind the alternator), 1st my local Ford dealer wanted $1700.00?! to fix it. The part costs almost $600.00!

Well, call Ford, argue, argue, loyal Merc cust, etc, long story short $600.00 out the door. Still not chicken feed, but not bad for an at that time 6 year old car. Anyway, you can tell if it's been changed thusly: the pipe that breaks runs across the front of the intake manifold, right behind the alternator. The "bad", original one is black plastic. The "fixed" one is cast metal, aluminum or magnesium, not integrated into the manifold. Take my word for it: check! After '97 the correct manifold became standard from the factory.

2nd, last night suddenly it would not idle. No rough running, etc, it would start and quit immediately. Did a quick search on "crown vic*" "won't idle" and after about 5 minutes of looking found a mustang site that had the goods (love the internet!!).

Called the IAC (idle air control), this part does god-knows-what, but if it sticks you get no idle (and no check engine light - no codes to help!). Reading around it is very common for it to stick or fail at about 75,000 miles, mine at 82,000.

On many it looks like a little starter, two bolts holding a can, with an electric connection coming off the end. On my car it was attached to the backside of the throttle body, with a large vacuum hose coming out the top, came off in 3 minutes.

Cleaned with carb cleaner, let dry ten minutes, shot a little WD-40 into it, reinstalled and pow! runs great.

That's it for my experience, although I think the power steering pump is about to fail, BIG surprise on a Ford . Also, I had a Ford tech tell me to be sure to keep the oil changed on the 4.6, if you do it'll "run forever".

Anyone else have any comments/hints/tips on the 4.6? Any easy power boosts or issues to look out for?

Pete

[Eric H]

Hi Pete,

The only other issue I can think of on the 4.6 and it's siblings is the spark plugs.
be sure they are kept torqued properly, i.e. kept tight.
There is only about 3/8" of thread on these and if they get a little loose they'll pound themselves out and eventually pop out, taking the threads with them! Nearly impossible to fix without pulling the head (and the engine)

These are great engines, I work for a Fleet with hundreds of them and the only serious failures are when they get run out of oil!

[spkrman57]

Pete,
Glad you got the "Land-Yacht" running again!
Ron

[Jstas]

Working at Pep Boys, I met many people with the mod-motors in thir work vans and trucks and racking up well over 150,000 miles without any problems at all. Only one guy had issues and he never did any maintenance on the vehicles.

As long as you perform your regular maintenance and checks on any 4.6/5.4 V8 or the 6.8 V10, they will run a good long time before needing major engine work. Save for the coolant pipe issue mentioned above and the spark plugs tending to want to pop out.

[Sandy G]

I wonder if the 6.8 L V-10 in my Excursion is really just an overgrown 4.6 or the 5.4 V-8 ? My tugboat has 81 K miles on it, & still runs like the proverbial top.-Sandy G.

[Yamaha B-2]

Same for the smaller 4.0L V-6 in my Explorer. I like it a lot mated to a 5-speed automatic transmission and a 'real' 4-wheel drive with a low range. Decent mileage at 20mpg on the highway and pulls us up and down the local beaches through deep sand in low-range 4WD without a thought. I'm very pleased.

[Jstas]

Originally Posted by Sandy G

I wonder if the 6.8 L V-10 in my Excursion is really just an overgrown 4.6 or the 5.4 V-8 ? My tugboat has 81 K miles on it, & still runs like the proverbial top.-Sandy G.

The 4.6/5.4/6.8L engines are reffered to as "mod motors" because they are a modular design. Each bank of cylinders, except for the ends, are made up of parts that were made with modular casting. Your 6.8L V10 has 10, .68L cylinders. The 5.4L V8 has 8, .68L cylinders. The 6.8L V10 is a 5.4L V8 with two extra cylinders added into the middle. They could make an 8.1L V12 or a 10.9L V16 and so on. They just have to take the blueprinted design and add as many cylinders as they need to between the two end pieces in the design. The computer builds the casting form and then the engine cast and out pops a a V...whatever sized engine and it cost them 1/20th of what a normal, new engine development process would cost. On top of that, it provides repeatabilty which improves quality control which als improves reliability and durability. Design changes are easy to implement and the real nice thing is that it's easy to make parts for aftermarket stuff.




As far as anyone wanting to make quick power with the Ford "mod motors", they respond disgustingly well to forced induction with either a supercharger or a turbocharger. Just make sure your setup is intercooled and you put in an oil cooler and a transmissino cooler for automatic equiped vehicles and you can pick up an easy 100-120 horses with a pretty low 6-8 pounds of boost. The kits can get pricey but when you look at how much power you gain compared to what they cost, they are a bargain. Other ways to make some quick power are to install a new exhaust system, get a reprogrammed computer chip and a bigger throttle body and injectors. I've seen cars pick up 30-80 horses with just those modifications. Start out with a Mustang engine already pumping out 300 horses and you can hit 400+ easily with very little work and never have to open the engine. The only issue is that the stock blocks won't support crazy amounts of power. The 4.6L will only hold roughly 550-600 horses so if you are going hardcore on the power levels, you need bottom end work. The 5.4 will hold close to 800 horses and then they need help too. The V10's are not really geared towards high performance but if you wanna make power there, the will make gobs of tourque so they would be good towing engines.


Oh, the difference between the cylinder volums of teh 4.6L vs. the 5.4/6.8L engines is a taller deck heigh on the 5.4L/6.8L engines as compared to the 4.6L. That is where the .11L of extra displacement per cylinder comes from.

[THOR]

Well I know from checking on the net after it happened to me the day I got my 2001 Expedition (dealer covered it) But 4.6L and 5.4L triton v8's from I believe 2001 on down are notorious for the coil packs going bad. Something to do with the hose that goes to the heater core leaks onto the coil packs. They corrode and fail, my mechanic told me one time they couldn't remove the spark plug it was so rusted in there. Loss of a coilpack causes rough ididling, real rough, and loss of power and each one is like $150 just for the part. My boss has a 96' expedition and he lost too coilpacks at 50,000 miles his has over 100,000 with no problems. Mine had 50,000 miles on it the day I got it and lost 2 coilpacks. If you look online some folks have had much worse and more frequent problems with them.

[Jstas]

that's not the coil packs going bad dude. That's the coolant crossover hose leaking and causing the problem. I haven't heard of any coil packs going bad on engines without the crossover pipe or at least the revised crossover pipe. Fix the real problem, the leaky or bad coolant crossover pipe.

[THOR]

Right but the leaky pipe is what causes the coil pack issue that is way it is only up to certain years then I guess they moved the pipe so that it didn't crossover the coil packs. No even sure if leakage is the problem might even be caused by condensation dripping down. Do a search it is a very common problem on certain years of the 4.6 and 5.4 Someone mentioned a kit you can buy to prevent it from happening on one of the F-150 forums.

[Eric H]

The coils do go bad from time to time, I wouldn't call it a problem area though.

Coolant from a bad intake or rain water (on the Econolines & Expeditions) can cause a problem but just as often they just seem to go bad for no apparent reason.

We buy em from NAPA for about $30

[Sandy G]

My V-10 doesn't really need any more juice, it's fine the way it is, but woe be unto him who bought an Excursion w/the gas V-8. I think it would be a slug-mine weighs 7400 lbs, empty. It NEEDS a V-10.-Sandy G.

[THOR]

I believe it Sandy, after driving a cherokee with a 4.0L straight six, my Expedition seems underpowered. The Expedition makes my old Cherokee seem like a Corvette. Of course the Expedition is supposed to feel like a tank I can't imagine an Expedition with a 4.6L or an Excursion with a 5.4L

[bgadow]

I knew this Ford mechanic, who bragged about being the best there ever was, he only drove Chevy's. He said these engines were junk, that he was replacing them daily, as fast as he could go, and that he'd love to rebuild them but they were so junky it was impossible. His boss was lucky to have a mechanic so good that he could replace all these trashy Ford junkheap motors. No, I don't really believe what this guy said. My only bad experience is with the V6 version (4.2L), I think every one of them thats been in our shop blows blue smoke & rattles on startup.

[madpioneer]

Keep the throttle body and plenum clean. Spray carb cleaner or equivlent at routine intervals. 4.6 Motor is notorious for carbon build up there from back lash of the RGV. Will cause power robbing condition slowly over time almost unoticed. Eventually will trigger 'Check Engine' light due to bad air/fuel mixture/flow. Not sure this is the same hose mentioned before. But there is a hose that runs thru the block carrying coolant. It comes thru the front of the block. It has to be eventually changed or your gonna have problems. I believe the manifold must be removed to get at it. Cheap part to replace but labor is the killer! 'Bar Links' at the tie rods on the front, their bushings go bad around 75,000 miles. When you hit a bump, pothole, crack in the road the front end has a clunking or clinking noise, very annoying. You can actually bounce the car with your own wieght while the car is parked and hear the wonderful noise. Will drive a person crazy if they are not familiar with this problem('What the h*ll is that noise!?').Bar links are cheap and you can install yourself in less than an hour!
If you plan to drive it over 100,000 miles do your self a favor change the coil packs. Especially if you travel alot you will thank yourself later. Heat alone breaks em down. At around 75,000 to 80,000 when you go to change the plugs do the plug wires and coil packs at the same time. Coil packs are around $40 each. Big long lower coolant hose will run you around $65 is really long, budget for that, it ain't your typical $15 lower hose. Horns are located in the worst location. In front of the driver front wheel. Water from the road spalshes up and causes horn operation loss until it dries out. Remove the connector bend the contact blade on the horn side to make maximum contact with connector lube with de-electric grease or equivilant. Re-install connector to horn. Then seal off connection with electrical tape or other that can water-proof the connector!
All this is based off my 1995 Grand Marquis experience.