Going back to the originalish topic I have just realised that on modern vehicles there are sensors that tell you an item has broken down and turns on a light on the dash. Sometimes the sensor will stop the engine or send it in to limp home mode to protect the engine. From my experience 9 times out of 10 the item that has broken is the sensor not the item it is supposed to be monitoring. Change the sensor and the light on the dash goes off and your back to happy motoring.

 

Or you run into other fun things. I have a 2013 XF and it rained a bit yesterday. I was driving and got an "Engine systems fault" warning. Came home and it was impossible to turn off the car, as the communication network must have been corrupted between the stop start button and the ECU that controls it. I ended up having to pull the fuse for the fuel pump and then disconnect the battery to shut it off.

After much hunting, it seems that one of the very undersized sunroof drain tubes was being pinched by a wiring harness and a piece of sound deadening, the sunroof drain overflows and drips on a massive power distribution box. I've taken everything apart and blew out the water with compressed air, but now I have to find the mechanical lock to be able to get back into the boot to reconnect the battery. What fun modern cars are where a few drops of water can bring them to their knees.

 

JB I have a 2013 XF Sport brake. Had exactly the same problem 2 year ago but not from a blocked water over flow. (I do not have the Sun roof). My wife came home and said lots of lights had come up on the dash. I went outside to see what the problem was and the car would not fire up. Auto so the little button for putting the car in gear did not rise so I was stuck in neutral, gearbox locking the back wheels and the engine would not start. Electric hand brake just to add to the woos and I could not turn that off. The position of the car on my drive meant it could not easily be towed off. I called out the RAC and the first guy spent three hours trying to sort it out on the Friday night. Did not give up as he returned with a second crew on Saturday afternoon and the two of them spent four hours trying but failing. They thought it was starter motor or alternator. They went home and on Sunday morning three RAC crews arrived (obviously a quiet time for them) and between them they jacked the car up got it on a dolly and towed it off the driveway on to the road and took it to my local Jaguar indy garage who has done work on my S Type for my and I trust. After a week of tests it turns out there is a 50p rubber washer sealing the washer jet motor in the front right wing which had lost its seal. The water from the jet was creeping along a wire into the main ECU board situated in the front right footwell. Water in a mother board does not make it work very well. My man William could not get a second hand mother board unit and a new one was £1300 plus 20% vat, fitting and programming to match the main ECU. Over £1900 total.. He took my unit home with him, dried it out in his oven then replaced some of the soldered joints that had corroded, rewired some bits (he previously worked in the Aston Martin factory as an electronics engineer) and finally got it going for me. Cost £750 all in which I was not going to argue with. But still more than a 50p rubber washer pump seal.

 

Oh dear, that ECU in the right footwell is what was above the sunroof drain and I think water got on it. Not looking forward to diagnosing this tomorrow!

Mine is AWD, so will need a specialist tow truck if it has to go to the dealer.

 

The one the mechanic did fix:

Our first house didn't have much of a garden and I was quite happy to cut the lawn with an old push mower. However, a neighbour insisted that it was too much effort and I should save time by trying his electric mower. In the end, I gave in and accepted the offer. He hadn't mentioned the thing was non-functional and generally falling apart. The drive belt was off the pulleys, the tensioner wasn't attached, the stop-start button was hanging loose and a cable wasn't connected - just some of the things I can remember. Of course, I couldn't give it back in that state. It cost me a couple of hours to do the repair work and some miscellaneous nuts and bolts before I could cut the lawn in about ten minutes.
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I hate it when I get around to doing a job that my wife wants me to do that she insists is only a five minute job but............
Not used the drill for six months or so after I had lent it to a mate. When I pull it out it is not working, Spend three hours stripping the drill to pieces, rewiring a corroded joint, oiling and cleaning the damn thing. Finally I get it working and complete the five minute job in just less than four hours. Another day wasted.

 

This kind of 'water on the brain' isn't new or restricted to electronics. Have you noticed how the top hose of the XK engine is just about vertically above the distributor? After my father bought the Mk2, it took us weeks to find the cause of the intermittent loss of sparks was a close to invisible drip from a hose connection.

 

In the 60's I drove my MK 1 like I knew what I was doing. Coming back from Montreal one night in a howling blizzard, no other cars on the road, my Jag just stopped. They had erected these vast walls of canvas or something that ran down the highway to keep the god-powered winds from just erasing all life. It was freaking shrieking. I popped the hood -- like I knew what I was doing -- and did a scan... noticed a wire coming out of the bottom of the distributor, and muttered: "I don't remember leaving that... like that!" So I pushed it around with my finger until it looked like... it should! Got in the car, it started right up, made it to class... Instead of being dead. Never happened again. So I left well enough alone.

 

That also happened in the time our Mk2 was in my father's care. I think he used a matchstick found at the roadside to wedge the ground wire in place. The strange thing is that during my stewardship, the car was absolutely reliable. Things broke, but it never stopped.

 

Of all the older jaguars I have owned the only times I ever had on the road breakdown problems were SU fuel pumps failing and in a MK1, one failure of clutch slave cylinder stuck full in
That is until recently when my 1996 X300 tried to pump the engine oil overboard via the oil pressure switch/transmitter.
By sheer luck I pulled into a rest area for a toilet stop and noted oil all over the rear of the car and a couple of drops on the ground.
There was just a smidgen on the dip stick and it hadn't seized but it came home on a tow truck. (The full story is in X300 section of this forum, what did you do to your X300 today)
Overall the older Jaguars were very reliable except for SU and Lucas bits.

 

I have only been let down twice by my S Type. Once the rectifier in my newish Dynamator failed and I was stuck with a flat battery (the Dynamator being a modern part) and secondly I had a break in a wire going to the coil which was giving me an intermittent electrical fault. I finally stripped the engine wiring loom back until I found the break and repaired it. (old wiring loom original to the car).
I don't think I have enough time left in my life to list the faults I have had with my sons X400 or my XF, all of which were mainly electrical problems concerning the ECUs, sensors telling the ECUs something was wrong and small poorly designed, poorly built with cheap materials, parts that snap with age and take days to strip out and repair. Electric door locks, seat switches and air vent motors none of which you have on a 1960s Jaguar. Now we are being forced into going with electric cars, with even more sensors, which to fix will definitely need a degree in electronics and a blood big computer. The dealers must be rubbing their hands.

 

The last time we got into the reliability of modern cars, I read through some of the surveys. Surprisingly, in terms of faults Jaguar (not JLR) were no worse than most others. Every make seems to be blessed and cursed by electronics. That's of course apart from most of the East Asian manufacturers that are only blessed. My X type and XK have, so far, arms and legs crossed, been faultless. A lot of XK (X100 and X150) will tell you it's the most reliable car they've ever owned. The Daimler, in spite of being made when reliability was supposed to be good, has stopped a few times. In all cases, we eventually traced back the problems to rust particles blocking the fuel pump, change over valves and injectors or a poor ground connection to the engine block upsetting the ECU.

 

Peter
I have had the same problems in myS3 Daimler.
Rust particles coming from the fuel tank being attracted to the very strong permanent magnet fields in the fuel pump causing it to fail.
I advocate fuel filters at the tank outlets and prior to the changeover valve and fuel pump.
Also a visit to the in-tank filter is recommended.

 

Bill,
I fitted filters and they helped for a while. The smallest particles seem to still get through and subsequently agglomerate into big, troublesome ones. In the end, we replaced both tanks, the fuel lines, and of course all the valves and the pump (the last for the nth time). We also had the injectors cleaned. Since then, everything has been fine.

Having trouble with a series 3 V12 is doubly frustrating because, for those who've ever driven them, they are up with the X300 as the best cars that have ever been made in their combination of silent comfort with performance.
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Bill. This is a more common problem than one may think in flooded pumps. They ultimately seize.

 

Peter: you are absolutely correct about the Series III V12 cars. Having owned a number of them I can say that the most frequent failure point is the ignition module in the ignition amplifier unit (first symptom of failure: difficulty starting or no start on a warm/hot engine).
And lest any reader say that this electrical failure is typical of Lucas and Jaguar, I hasten to point out that the original module is made by General Motors (Delco D1906). If you are aware of this weak point, the prevention technique is to put an easily sourced D1906 in the glove box. That cuts the probability of failure by 98.7 percent!

On my Mk 2 I have been left at the side of the road twice by the same simple fault: in both cases the locating tab on the underside of the ignition rotor had sheared off (!) allowing the rotor to do what rotors love to do: rotate freely.
Apart from this, the car has been completely reliable.
A bit difficult to see but these are the culprits: both rotors have the sheared peg; both of these are original period (60's) rotors, I believe. I now carry an extra rotor in the glove box!

 

Glyn
The series 3 XJ6/12 has an external pump.
However, I know what you are referring to as I have had to replace the fuel pumps in the Mitsubishi Colt (shopping trolley) and Subaru Forester (aerodrome tow car) in the last 12 months.
Cheers

 

Gregory, I came lose to a similar problem. It was quite a while ago.. My car was suffering a very slight hesitation at around 60m/h. It was almost imperceptible and might have passed unnoticed in another car. I had no idea of the problem. I took David Marks on a short drive and he identified the cause quite quickly as the rotor arm. Since the only people to work on the car regularly are David and myself and both of us would only buy parts from a Jaguar dealer or SNG B, I can only guess that it was one of those lower quality items from China that had slipped through the net, probably into a nice reproduction Jaguar or Lucas box.

 

Thanks Bill. I just learnt something! I lost interest at the end of the compact era.

 

You shouldn't. Although the XK engine was getting long in the tooth, the series XJ were very much the best in the world and in many ways they still are.