Back Axle noise, especially on the over-run.
Don't be tempted to buy a car with any appreciable noise on the 'back end' You may have been told that the noise is due to a worn wheel bearing but this often not the case. Mostly, worn differential bearings are to blame.
Repair is expensive in both terms of parts and labour and there aren't many mechanics that can (or will) do the job. Finding a second-hand differential unit that is genuinely quiet is difficult, and the last thing you'd want is to spend a lot of money in having a used Diff. fitted only to find it is also noisy and the assurance that it is 'guaranteed' is worthless. The only way to buy a used unit is to stick to what you can test drive before buying and make sure that it is that unit you end up with. A new or reconditioned differential unit will set you back a long way, possibly costing half of what a car is 'worth', plus the labour of removal/refit.
Note that the labour element of this job is unpleasant to undertake, whilst seized bolts can hinder the job further. In my experience, the labour cost of removal and refit of a diff. unit is somewhere around £400 - £500, and that is without the supply/ repair of the diff. I have got 'lucky' in finding a used diff. unit that proved to be quiet but the total cost of buying it and having it fitted exceeded £800, not good if the car is 'worth' only £2000.
Alleged 'Spongy' Brake Pedal
The X300 braking system is quite different to that fitted to the XJ40. The XJ40 has a real 'drivers' pedal, moving very little before the brakes are being applied.
The X300 (and XJ8 for that matter) have much more pedal travel before the brakes actually come into play.
I have heard XJ40 drivers make comments about 'Sponginess' of the X300 / XJ8 brake pedal and making an incorrect assumption that there is 'something wrong with the brakes' on X300's or XJ8's. I even had one MOT tester try to fail a car on 'no reserve footbrake travel' but soon educated him on these differences by inviting to speak to a Jaguar Agent and giving him the chance to try another car.
The plain fact is that the X300 / XJ8 has more pedal travel than XJ40's and some other makes. When someone claims to have found a 'brake fault' it is often due to them being unfamiliar with the model.
Digital Dashboard Clocks
I only see around 5% of cars with this clock actually working. There are replacements available from E Bay or similar, costing £35 - 70 plus fitting which can be DIY, although there is quite a lot of work involved removing trim etc. I have heard that the clock can be repaired by simply sliding in a piece of cardboard behind the PC board connection in order to tighten it up but I have not tried it to date.
UPDATE -
I found the description of this repair kindly posted by someone on the excellent Jag Lovers website. Click this link - Jag Lovers - Dashboard Clock
Oil Pressure readings low or Zero and Oil light coming on
This is a common problem, especially on older or higher mileage cars. It can be alarming as it often denotes an engine which is about to expire on other makes. Worry not. I have had several cars that have shown zero Oil pressure, normally just after warm up. The X300 engine is 'bombproof' and I have never seen one quit in such circumstances. When checked out, it always has actual Oil pressure if checked with an in-line (mechanical) pressure gauge. The cause of the errant 'Zero' pressure indication is the electronic sensor which fails to work at certain temperatures when close to the end of its useful life. The cure is to fit a new or even a used sensor. This is a relatively easy thing to do although it is hard to get at.
Central Locking and Alarm Key Fob not Working
Key fob transmitters have a hard life and do wear out. It may be that new Fob Batteries (there are two, part number 2016) will bring the fob back to life. If that is the case then you are lucky. We often see fobs that have only one battery fitted by a previous owner and its not surprise that the fob does not work. Again, if that is the case with your fob you might get lucky, because....
A replacement fob costs around £120 plus VAT from Jaguar and then it must be adapted to the car. A secondhand one can be bought and adpated to suit the car if you can find one that works.
Cars that have 2 servicable fobs are rare, mainly because the first fob packed up and a previous owner moved on to using the second one. To be fair, getting one working fob with a car that has covered 100k miles is a bonus. Two working fobs is almost unheard of!
If you haven't got a working fob at all and don't want to replace it, you don't have to buy one at all. The Alarm will be armed and disarmed by using the key to lock the doors. When opening the doors you have to get the key into the steering lock and switch on the ignition pretty quickly to stop the alarm horn sounding. See the Driver's handbook for more on this.
Boot opening (external) switch not working
The button used to open the X300 boot from outside the car operates a small switch.
This can fail, although most often the wiring that crosses the boot hinge will have become stiff and broken through. It is not expensive to fix the problem but like many electrical jobs it can soak up a lot of expensive diagnostic time. It is always much cheaper to use the boot button inside the car, or the key from outside and leave well alone!
Heater not supplying hot air
In just about every case, this is due to the failure of the electric circulation pump, fitted on the NSF inner wing. Replacements are not cheap from Jaguar although a used one might be good. Specialists like David Manners can save you money on a new one.
NOTE! If your car is LPG converted a failed heater coolant pump can cause all sorts of problems because the LPG system relies on hot coolant being supplied by the heater circuit. If it doesn't get that, the LPG system will not perform properly.
Another cause of heater failure can be Air Locking, especially if the air is trapped in the heater matrix. This problem is much that same as Air Locking in a house radiator and has the same cure. There are various methods for 'bleeding' the air out. In extreme cases we've had to raise the front of the car whilst bleeding air out of the matrix.
If you bleed the heater matirix successfully only to suffer the same problem later on, start looking for a coolant leak before things progress to a more serious level.
Screen Washer Pump not working
Most often the pump itself will have failed. It is not easy to get at, requiring the removal of the OSF inner wing liner. Jaguar charge £47 inc. Vat for a new pump although note that many types of Ford screen wash pump can be made to fit. I have bought these at £2 each from a breaker. If you go down this route, take some of the wiring and the connecting plug along for the ride. Often these differ whilst the pump is similar mechanically.
Other causes can be simple blocking of washer nozzles and pipes or failure of the in-line non return valves.
There is a pictoral 'how to' item on Screen washer pumps on one of our other Jaguar pages - Jaguar faults
Rear Bumper Top Face Bright Trim.
These are often dented by careless folk dumping heavy items on top of the bumper before opening the boot. The top trim is not chromed steel as many expect, but high quality stainless steel. A new replacement trim costs £165 plus Vat from Jaguar. They are held on by all manner of awkward clips which break easily. Also be aware that the bumper has to be removed before replacement can commence, something which brings its own problems in terms of seized bolts and broken plastic.
Add the labour cost to the cost of the replacement trim and you could easily spend £300 total. If you are lucky and the dent is not serious, it is possible to remove the trim and carefully roll out the dent. For best results, ask an experienced panel beater to do this for you NEVER use a hammer on the back of the trim without a sandbag on the other side or you'll end up with a worse dent in the other direction!
Rear Windows not working
This is another common X300 problem which is often due to simple lack of use. The motor is not too hard to remove and may respond well to freeing oil and TLC. You can plug the motor back in when it has been removed and check it for operation using the door switch (with ignition on) but mind your fingers!
Rear Shock Absorbers Rattling noises on the back end
This problem is often passed off or misdiagnosed as loose exhaust mountings, items moving in the boot or perhaps a loose rear bumper. If the noise occurs most often after going over a pot hole, it is more likely that the mounting bushes and bearings of the rear shock absorbers are to blame.
If the shocks themselves look old it is often a mistake to have them re-bushed. The only way to deal with this is to fit complete new shockers or have then fitted. The Jaguar replacement items are very expensive although David Manners supply a new pair (and I'd only recommend fitting a pair) for £127 delivered.
Don't be tempted to buy cheaper items as the top of the shocker shaft can snap right off during a good jolt, meaning the job must be done all over again. Removal and refit is, like the rear differential, not a fun job. Labour cost is around £150 a side (as long as none of the bolts shear off when being undone) making the total cost of a pair of rear shocks around £450.
I do not recommend DIY for this job. The good news is that the handling of a car with worn and noisy rear shock is dramatically transformed by fitting new ones!
Aerial Mast replacement
Often these are broken, damaged or simply seized. If seizure is the problem they do not normally retract or extend properly. The major cause of seizure is lack of regular cleaning of the mast by the previous owner or driver. As prescribed by Jaguar, the mast should be cleaned every 2 weeks or so using WD 40 and a soft cloth, wiping in an upward direction only. This stops the dirt from being pushed into the joints of the mast. If the mast has to be replaced beware that new ones are not cheap - £47 from Jaguar.
Air Conditioning not working.
By far the most common used X300 fault. The cause is often no more than a lack of use by the previous owner(s). As prescribed by Jaguar, the Air Con, should be turned on every 2 weeks or so to keep it maintained, Winter or Summer. The reason for this is simple once Air Con is understood;
Air Con. has many mechanical parts that require lubrication, bearings, seals and so on. The Air Con. system contains a gas that tends to remove ordinary mineral based oil or grease. To get around this problem a special lubricating oil formulation is added to the refrigerant gas. This oil only circulates to where it is needed when the Air Con. system is working. If this oil is not circulated, mechanical seizure can result.
Secondly, the many seals that keep the gas in the system will tend to dry out and shrink if they do not get a regular supply of this special oil. If the system isn't used regularly the seals will shrink and the gas will escape, leaving the system inoperative the next time it is called upon. As a result of this there is no special oil left in the system either. You will hear many people speak of a car's system needing a 're-gas' but this is often unsuccessful. Once those seals have shrunk to a certain level they will not come back to useful life and the gas just put in will leak out within a few days. A large repair bill then looms.
It is easy to spend £1000 or so on a Jaguar Air Con. System that has been neglected. On older cars it has to be judged as to whether it is worth doing this. If you are lucky enough to have Air Con. working in an X300 or any other car, look after it by running it every 2 weeks or so. It really is a case of 'Use it or lose it'.
Note that cars fitted with 'Climate control' only but having no Air Con, system are actually preferred by many If Air Con. isn't fitted, it cannot break!
Cars that will not allow 'Drive' or Reverse to be selected from a start
If the brake light bulbs (or the circuit that feeds them) do not work, the gear selector interlock will not release from the 'Park' position when the brake pedal is pressed. It can take ages to select a gear in such a case. Also note that the Brake light switch itself can be faulty or out of adjustment, causing a similar problem although the bulbs are both good and the circuit is working.
Front and Rear Brake Discs - Warping and Wear
Wear is clear enough to diagnose. When the brake discs become too thin they need replacing. They are checked on MOT but sometimes a 'borderline' case will be let through the MOT, only to be well below par after a period of frequent use later on. Only replace them (or have them replaced) in pairs, 2 front or 2 rear, and with new pads. If you are DIY'ing, make sure the protective coating is cleaned off the discs before fitting the pads.
Disc Warping will manifest as 'pedal bounce' and may be felt through the steering, especially in the case of front discs. Replacement as prescribed above is the only realistic cure.
Petrol Cap drain blockage and Water Contamination of Fuel
Owners still using Petrol to run their cars get to see the petrol filler every day or two but those running on LPG rarely see it!
The filler drain hole and its filter are both prone to blockage by leaves and other debris, causing the filler to collect water. This is really undesirable. The water can leak into the Petrol tank under the submerged cap and cause you all manner of problems later on.
Check that your filler drain is clear. If it isn't, take out the filter and clean it. The drain pipe itself can be unblocked with a length of stiff wire. Test it out afterward with a little water and remember to keep an eye out for the next blockage (most likely in Autumn). For pic see our other page on Jaguar faults
Car Wash Damage to Paintwork
Easy to spot and often worse on top surfaces, roof, bonnet and boot lid. The laquer finish is 'fogged' (scratched) by the coarse nylon brushes. Often the damage cannot be polished out. Avoidance is easy - Never put your X 300 through a car wash!
Cars that Idle Eratically or Stall at Junctions
The first thing to check for is any air leakage after the air mass meter. The rubber 'Bellows' fitted to the inlet manifold is the main area to concentrate on.
The second thing is much more subtle - Have you recently changed the spark plugs or had them changed?
X300's are notoriously sensitive to spark plug resistance. If this is incorrect, the ignition timing can oscillate between high advance and retard values, making the engine speed change dramatically. This makes the engine idle badly or stall. Some engines may not even start at all. If you find this just after changing the plugs, put the old ones back in until you have sorted out what is wrong with the new ones.
Replacing Oxygen (Lambda) Sensors
These are a consumable item and have a finite life. Testing or replacing them can be difficult.
We came up with the X300 Lambda Connection Modification to make life easier.
Siezed Front Brake Calipers
A lot of X300 calipers sieze, we have replaced many. Dissasembly
shows the cause to be split rubber piston seals which allow road
water and salt in, resulting in corrosion. Almost without
exception, the blame lies with the last but one person to change
the pads, having used some unsuitable instruments and little care.
The seal is damaged then, and in time corrosion takes its toll on
the unprotected piston. Next time new pads are fitted, even by a
careful person, the corroded portion of the piston is forced back
into its cylinder and it will eventually sieze up.
Replacing the Fuel Filter
Take great care when undoing the union nuts to the filter - Often
the fuel pipes are corroded and fall into a pile of dust. If that
happens it's best to go back to good pipe both sides and splice new
sections in, but it would be unwise to do this with worm drive clips
and bits of fuel hose. Get same diameter push-on hydraulic or air
connectors, they are an absolute doddle to fit and no risk of leaks
as they are designed for far higher pressures than present in
Jaguar fuel delivery. Best to check that what you are buying will
be fuel proof too. For the missing pipe you can use new plastic
fuel pipe. At the filter end(s) things might be easy or complicated,
depends on the conditions of the union nuts. If they are scrap then
you could replace them or go for a filter with different
connections that can be bought to match.
