I'm about ready to pull the trigger on an 03 4.2 w/nav S type. To my understanding they are the same engine as theproblematic '00-'024.0s. The new 4.2s now use forged pistons, different heads and exhaust manis. Did they ever fix that plastic timing chain tensioner? Do you still need to remove the intake manifold to replace the spark plugs/routine maintenance? Is removing the intake mani that hard? Do you need to scrape off the gasket and use a new one? Any other overall reliablity problems with the early 4.2s? Thanks!

 

you only have to remove intake on 3.0 liter V6.., 4.2 V8 is easy to change the spark plugs.. 4.2 is a good car .. had a couple tranni problems in the beginning but is okay now.. overall good car..

 

bacardi 151 i have the same car no problems so far it has 22,723 miles on it and going strong.

 

Great info! So they replaced the pastic tensioner for the timing chain? Do I need to bring it to a jag dealer for any recalls?