XF Hydraulic Lifters
I've got an 87 XF which has a reconditioned motor in it with nearly 100'000 on it. A few months ago it started running really rough mainly when cold and stalling. This later progressed to full time problems idling (almost immediately after an oil change). Problem was at times it would idle smoothly for a little while and then return. Drivability was not an issue. Had me absolutely stuffed so I replaced the carby, Checked all seals, pipes, played with choke, re-tuned it, new leads, new spark plugs, checked for sticky valves, compression tests etc,etc. By pure luck (just as I was about to rip off the head suspecting a burnt exhaust valve) the engine started making tack-tack sounds. Straight away I suspected and found one of the hydraulic lifters was the cause of all my problems. Cost me $2 for a second hand lifter and an hours patience pulling out the old lifter. The old lifter was very worn on the bottom. It was so worn that when sat on a level surface it had a very noticable lean. This lean explains why the car sometimes idled o.k. - as the lifter would rotate in its' bore. The motor now runs fine again.
What I would like to know is - is this a common problem with XF or all 4.1 motors? I've heard that oil galleys on these cars are known for problems. Or, is just a case of the tappet being "lazy" and copping a hammering from the CAM? Could it be the people that reconditioned the motor did a poor job as 100,000 is not that much milage for this sort of problem? Could the CAM be worn? Anyone else had this problem? Any other thoughts.