I was thinking of buying a 99 f 250 4x4 5 speed super duty thats for sale.Its in good shape with about low miles.But someone told me not to buy it cause this year and a few other years of the super dutys have a problem with the spark plugs falling out while you drive down the road.Whats up with that anyway?IS this even true i mean why would anyone buy a truck that does this? or is the guy just joking?I really like the truck but if thats the case I wont buy it.need info on this thanks.

 

The 5.4 for sure and v10 engine can have issues with sparkplugs. They are hard to replace and prone to messing up the small amount of threads they have. There are a lot of write ups over this issue

 

As with ANY engine using aluminum heads, it is very easy to damage the aluminum threads when removing and installing spark plugs. If the plug is not torqued enough, it will loosen and hammer against the threads, fatiguing them until they fail. If the plug is tightened too much, the aluminum threads will be distorted or sheared.
In either case, the plug can "blow out" or "spit out".
If you do research, you can find someone complaining about the same problem happening with ANY engine. I've fixed many, many stripped aluminum heads over the years. BMW, Honda, Kawasaki, you name it, somebody, somewhere has managed to f it up.

The early Ford modular engines have gotten a very public bad reputation for this happening. I think there are 5 reasons:
1) The gorilla effect. Most people working on Ford engines at that time were used to steel plugs in iron heads where you could grossly overtorque with no risk. So they got used to grossly overtightening and don't use torque wrenches OR follow specifications. Do that just once on an aluminum head (ANY aluminum head), and it will eventually fail.
2) The early 2V didn't have very many threads in the head, so they were even more susceptible. In some engines, there are more threads so you could tighten 2x over spec and get away with it. Not on the '99. The later 2V had many more threads so not as many have been damaged. But I'm sure some have been by "SUPER gorillas"!
3) Ford used taper seat plugs instead of crush washers. Crush washers are great because they "absorb" a good quarter to half turn of excessive torque, protecting the gorilla from themselves. Give a taper plug an extra 1/4 turn "for good measure" and you just destroyed the plug threads. These things bottom and reach spec'd torque almost immediately.
4) There are literally millions and millions of these modular engines out there (almost all Fords for many years), so there have been a LOT of them damaged. So you hear about them much more often than others.
5) Ford has addressed the issue in a very wishy-washy way that makes them look comical at best, clueless or stupid at worst.

Bottom line: If the engine had been properly cared for, the odds of it happening are very, very slim. But the safety margin is unusually small on these engines and requires care, knowledge, and proper technique.
If a spark plug was installed by a gorilla, just ONCE, the threads are weakened and it is guaranteed to fail.

As an engineer, I wrestle with whether it is a design flaw or not. Used properly, and repaired per instructions, they work perfectly. But they are not very "idiot proof". If I was an engineering manager at Ford, I would have never allowed the design to be released as it was. Yes, it is a perfectly sound design and can meet functionality requirements, but there are a LOT of idiots using Ford's products, so I would have insisted on a much more robust design. My 40 years of experience says at least 3X safety margin....

 

Well said.

 

Keeping in mind the torque spec is only 15~~ft/lbs for the plugs if I remember correctly. My FIL asked me to change the plugs in his 4.6 last year. He bought the correct plugs from Ford and removed one to check it. He said he put it back and tightened it to what "felt about like how much it took to remove it". I cringed... So we changed his plugs and he questioned my using a torque wrench and how they weren't tight enough. No trouble yet but I still worry about the one.

 

I think part of the problem was the plugs themselves. On new motorcraft plugs now there are more threads, I think that helps. Also most shops now have the repair kit to fix the threads in the head. Can be 200 to 400 a hole, depends on where you go. Maintenance is key. Do the tune-up when you are supposed to and you should be fine.

 

Get a diesel - no spark plugs to worry about....

mwsF250 covered it very well - and with buying ANY used vehicle, you take a risk. Look it over thoroughly, and maybe if you're lucky you'll come across someone local that is familiar with the engine and can inspect that for you. Good luck to you!!

 

mine blew three all original ford factory installed plugs!

 

wow I dont know. I think ill look for an older f 250 like one back from the old body style from the 90s.I like to change my own spark plugs and with these super dutys I dont think i would want to.guess ill look for a 96 or 97 f 250 4x4 no offense to any of you but it just sounds like a big problem that i want no part of.heres to going back to the older ford pickups with the 351w engines I can change my own plugs lol.

 

keep in mind the issue is no were near as big a problem as it might seem reading a few threads on a internet forum...

sure some of the early year trucks had it happen, but its not like every truck had the issue...

i've had a 99 V10, and now own a 2003 V10, and ive had ZERO spark plug problems...

 

I used a '96 F350 with 460 gasser (2WD but dually) before the V10 (4WD but mild lift and much bigger tires).

The v10 puts out noticeably more torque, a lot more peak horsepower, and gets about 2-3 mpg better. It flat pulls circles around the old tech 460. I imagine it would be shockingly better than a 351.

Not saying you shouldn't do what you want, you should. But want you to know as many of the tradeoffs as possible.

What I did: Bought a perfectly straight, lightly used '99 V10 for $8600. Drove it until a plug spit due to previous gorilla abuse. Built a new engine using PI heads with plug inserts in all 10 holes.
Swapped engines. Total cost: Under $11K.

 

Hawk - You are the first person who I've come across that actually had it happen to them. I've heard lots of "a friend said...."
I would love to learn more about it to help me understand the total story.

I have a theory that Ford over-reacted to initial reports and had the factory reduce plug torque... but went too far.

What was the manufacturing date of your truck? V8 or V10?

 

If this was the case, I'm sure you would have just been fired and some other rubber stamper would have your job. Perhaps where you work is an engineering-driven company, but in most companies, the engineering manager's job is to first make the time line and second take the blame when his expertise is ignored. Sorry, but that's how things work in a sales driven company.

 

Kinda off topic but...is there another kind of company??

 

This post reminds me of what I did earlier today. Which was picking up my truck after blowing it's 2nd plug in 15K. Factory plugs where changed at 150K without a problem! Then after 5K the first blew taking out the coil and the wiring to boot, 2nd time another coil and the EGR valve. It's got 170K now and after these 2 incidents doesn't run as smooth as it used to, but hey it's got some miles on it.Would I buy another Ford?YOU BET!