My 2001 Xk8 has three dead cylinders after previous owner ran very hot, along with it having 169 K miles. looking at used engines all the sites ask engine number to replace with same number series out of a 2001 . Wouldn't it be more logical to buy a 2003 4.0 that would have upgraded tensioners? Were there any changes in that motor that would not allow me to install 2003 motorin my 2001 XK8 ?

 

I don't think you can. Others will chime in but 03 and up is a totally diff beast, computer just to start with. 97-02 is a 4.0 03 and newer is a 4.2.

 

It can be done. Here is a guideline: https://www.jaguarforums.com/forum/j...63/#post177881

 

The 2003 XJ were the 4.0L.

AFAIK, there is no barrier to using it in the XK8.

 

I have a 2001 XK8 that had a chain issue that ruined the motor. I bought a 2003 XJ8 with a 4.0 and put that motor in the 2001. No problems at all.

 

How many miles on the chain issue? And did you mean chain tensioner issue, as in the secondary tensioners?

 

My car had 93000 miles when the B chain broke due to secondary tensioner failure.

 

I have just bough a 2001 XKR with a bad motor. I have not gone into the motor yet to see what is wrong, but I know it is something very bad. Anyway, I too would like to swap out for a newer motor. Can a 4.2 engine be swapped If you change out the ecm too. Will the ecm connect to the rest of the wiring? I read the 4.0 to 4.2 info, but could not figure if the supercharger from the 4.0 engine will work on the 4.2 block. thanks for any help. steve