I recently looked at an immaculate, low-mileage Jaguar S-Type for a friend and it was truly like new. Although it was several years old, the owner lived abroad and kept the car in South Africa so that when he came here on holiday once a year the car would be waiting.
Heaven knows what arrangements he had made for storage, battery care, etc. Anyway, the car drove well and sounded and looked good, so I left it at that.
As with many upmarket cars, the S-Type, although pleasant to drive, has earned a reputation for niggling faults and is rather tiresome for DIY work. For example, to change the spark plugs on the offside of this V6 engine the inlet manifold has to be removed. Not the end of the world, but a chore all the same.
A full service history is important when buying such a car because even using the incorrect oil may bring about all sorts of problems. The variable-valve timing system has a spring-loaded actuator that relies on engine oil for its lubrication. Incorrect or dirty oil will quickly clog the mechanism and cause a fall off in performance and rough idling. There is no fault code for this mechanism although investigation might show high hydrocarbon emissions.
DIAGNOSING PROBLEMS
The S-Type, partly depending on how it is driven, drinks a fair amount of oil, so it is important to check the level weekly. If you do take the car in for regular servicing, Jaguar agents are the best bet because they should not be tempted to neglect a full plug change or use incorrect oil. Besides, although the cost may be higher, the agent’s technicians will have the experience to diagnose problems when no fault code is stored.
Needless to say, along with regular oil changes, the correct original equipment filter should be fitted.
Any misfiring, however slight, should be viewed with apprehension, if not terror! The coils often give trouble on this model. Initially, if cash is short, a minor misfire may probably be ignored, but a major one, possibly accompanied by a warning light, could damage the catalytic converter and that means big bucks.
ELBOW JOINTS HAVE BEEN KNOWN TO SPLIT
Ideally, when a coil fails, an oscilloscope test is called for. The common DIY way is to buy a new coil and try it on each cylinder in turn until the misfire disappears. Some workshops recommend that if one coil fails, the whole six should be changed. I agree that this is ideal, but the cost of that exercise is beyond many of us. Whichever way you choose, always fit new original equipment spark plugs when renewing coils.
Emission controls, beneficial as they might be for our lungs, have caused many a headache. The positive crankcase ventilation pipe on this model has a couple of elbow joints that are known to split and cause air leaks that affect idling and may even cause stalling.
As the condition worsens, there could be a fault code. Otherwise, before it gets to that state, listen carefully for the sound of air escaping. If there is hissing, pray to whatever gods may be that it is the top hose that is responsible - the bottom one is a pig to get at. - Star Motoring