well, here goes. firstly, im no expert mechanic or motor technician. i have however had a couple of really bad xj40s, so have an idea of some of the problems to look for. Before buying an xj40 do some research online about the cars and watch the bidding on ebay for some time before jumping in as the prices of these cars vary considerably. Many people will probably find that if this is their first jag that nothing has ever felt so smooth quiet and effortless to drive and cant believe that only £200 quid paid for it. An absolute bargain :) yep, thats exactly what i did (MUG!) Totally bowled over by the leather seats and walnut dash and the leaping mascot on the bonnet i joined the people who bought a lemon. A cheap lemon but a lemon none the less.Swaggering into my local garage with a grin to show the boys my new set of wheels i felt like a dog with two **** That feeling was very short lived :) with just a month left on the mot i was told that the car was about to fall apart and would probably cost more to put right than buying a new one. Over and over the mechanics would say "oh thats a common fault on these old smokers" The list of faults was pretty rough.
Excessive corrosion on floor panels and sills. (inside the car is padding which needs to be removed in order to weld making it a very expensive repair) Twin headlamp units corroded.Valve guide oil seals needed doing. Self levelling suspension not working correctly. Oil leaks in numerous places.Apparently a jaguar engine will explode if it doesnt leak oil :) Cathode ray dash display had numerous faults and this units failure was causing other problems.Hydraulic fluid leaks all over the place. speedo inoperative. aircon failed. passenger door handle snapped. rust on bootlid, rust on bonnet. rust on fuel lid. There were other faults but apparently these are all ones to watch out for as they are very common if the car has been neglected. General consensus of opinion seems to be that the 4litre is the best of the engines. Of course this was a 2.9litre so was the worst of the bunch.
Go for the car with jaguar service history and ensure there is no rust. If you are not a competent mechanic then get the vehicle inspected as it will save tears in the long run. The later xj40s saw many improvements over the earlier ones. The analogue dash being far less tempremental than the cathode ray type.