owners manual states to change sp. plugs every 30,000 miles. just bought 2006 jeep commander with 31,995.miles.Seems like an awful short period of time.Thats why I want to know if the 4.7LV8 has aluminum heads you have to be careful not to strip them threads
Because (most) of the people on here are guessers, I personally don't like this engine (German designed thing), better change them at 30K Lol
tighten them til snug u should be ok, do not go all Macho man randy savage on them. if it's your car you should know. just tap on the heads or look at the color. aluminum is that color, steel is not- darker. plus u can just tell by looking at them. or tap the metal to see if it's real dense. aluminum is not and sounds more hollow high pitch than steel. 30K miles for plugs is rather quick. I get 75K at least on Hondas. buy platinums if u can
Everything is aluminum these days including the engine blocks. You dont want them too tight obviously cause they will strip, but you dont want them too loose because they will work themselves out of the hole. If you're still unconfident in being able to do it by hand, go to autozone and rent a torque wrench, put down a deposit and when you're done, get your deposit back. They can also tell you the torque spec for your spark plugs so you know how much to give it. Hope this helps. -Chris (Lead Tech - Hamilton's Car Care)
Not sure if it does but just change the plugs when the engine is cold you can strip the threads in any head if the engine is hot also when you install the new plugs use a anti-size lubricant on the threads this will help down the road. The reason you have to change them at 30k is because they use copper plugs you can switch to a single platinum plug.
The 4.7L uses aluminum heads and a cast iron block. The intake is glass filled nylon (plastic). (don't know where these people get their info from on here) You don't want to leave any plug in an aluminum head for 100k, even if the plug can last that long. That's why they don't bother using platinums in the first place.
