I got my new K&N filter today, and was eager to do my first little 'mod' to the car.

I got three of the four bolts of the air box off, but #4 wasn't having any of it. The nut is rusted on, and when I turn the bolt, the nut turns with it.

I've doused it w/ WD-40 to no avail. Still stuck. The geniuses at Ford designed to so that it's damn near impossible to get even a pair of needlenose pliers in there to grab it, and even if you can, it's a SMOOTH ROUND nut! I can't get the pliers to bite enough on it to break the bond.

Has anyone had this problem before? How did you solve it?

I don't suppose something like this would be covered under warranty, would it? [:D]

try usin a very long either flat head screw driver or somethin thats long and won't bend and just hit it...over and over :) maybey not screwdriver cause it'll bend but somethin hard that won't....just a suggestion
-Joe

Yep, happens all the time, if it's not under the hood, then it's lugs. Try leaving WD-40 on the bolt over night, and don't mess with it til morning, wipe it down then give it a try. If that doesn't work, then get a really thick plumbers putty, cover the existing bolt with the putty and put a bit larger nut around it, or putty a socket to it (a socket you won't need later - cuz it'll be goner) But, I recommend going to a muffler shop and have them professionaly take the bolt off, they'll weld a screw-like piece to it and just tork & twist it off. This way is less mess and a sure way not to screw up your car. Good luck!

I'm a brand new member so hello everybody!

Just went through exactly the same thing putting a K&N in my recently purchased 2000 SE with 5 speed, Zetec. I noticed that the other three nuts are of the "captive" variety, while this stubborn one appears to be an ordinary nut, so I assumed that the captive one must have gotten relpaced due to losing it or something. I didn't know this was a common design problem. Anyway, I couldn't get anything to work and was getting very angry- so angry that I went and snapped off the two plastic tabs that surround that nut with needle nose vice grips- then I was able to get the vice grip securely on the nut and finally get that bolt loosened. I left the vice grip in place so the nut wouldn't fall down, and also to keep nut lined up with the hole.

Happy ending- it worked! By the way, I find the K&N filter immediately gave me much improved throttle response.

Dave