www.jec.org.uk

Hello Folks,
As a migrant (vagrant?) from the 308 and XJS BB's I hope someone can come up with a possible cause and solution to this problem.
This car is a 2004 V6 350 (78000 miles) which has performed perfectly for a couple of years under my friends ownership (unfortunately he doesn't get on with computers hence my request!) A couple of nights ago he was travelling along an empty motorway at around 70mph (well I believe him) the car suddenly lost all power but headlights and stuff were still lit. He coasted to a halt on the hard shoulder and saw the 'Transmission failure' message briefly. At a stop he sat for a few minutes trying to work out his plan of action so late at night with his Wife (who has had some major surgery not so long ago) As I said he is not into computers and this car has them by the shed-load. As we all would do, he thought 'what the hell?' and turned on the ignition - no messages, so he tried starting it and it responded and ran perfectly for another 40 miles home. I have suggested he gets it to a diagnostic setup to see if there are any codes showing and also to check the battery - not sure if the 350 is as susceptible to reduced voltages in the way that the 308 is?
What I'm really asking is, is this a common fault caused by a failing sensor or is it the begining of terminal decline?

Regards,
Ian

350 is mega relaible, 80K miles is nothing for one of these cars, look on any site and you will see cars well north of 200K miles now

transmission on these is again pretty robust, they can leak oil around the sleeve around the loom seal, this is best replaced at oil change

350 like all previous gearboxes is NOT sealed for life, I would suggest at 78K an oil, filter and said sleeve are changed, the gearbox ECU reflashed along with the engine ECU as they both talk to each other, bet thst cures any issues, and the car will drive like new again

the other thing to check on 350 is the earthing pints behind the headlights, remove the plastic slam panel cover, and locate the two studs that hold all the earthing wires to the cars shell, this is a steel stud which reacts with the alloy (others will know the correct terms here), the stud falls of, or gives a poor earth prior to falling off, which in turn gives some seriously weird and wonderful electrical conditions, flashing headlights, handbrake failures, wipers with a mind of their own, both my 350's have had this failure, worth a check. Remake the earth with a new bolt through the front panel, job done,

350, like 308 is susceptible to failing batteries, they do need to be 100% good, i would agree a quick scan, clear any codes and drive and see what happens

where in the UK is the car based, we can then hopefully point the owner in the correct way to a good specialist

Hi Rob,
Many thanks for getting back with all of that useful info. The car is in Southport (Lancs/Merseyside) There is a garage not too far away who say they have diag equipment - but I think it would be better to have someone who knows these cars in detail to look at it.
The earthing stud problem sounds a simple route for him to check too.

Totally separate from this, I have 2 new articles with pics on my web site for the 308 (seat refurb and front wheel bearing replacement) Do you think Nigel could use those for the mag sometime?

Thanks again,
Ian

Ian

yes on the articles for Nigel, send then to me or direct to Nigel

If the car is on Merseyside, then Bob Bate is your man, he has all the latest Jaguar spec diagnostics, look NO further, details here

http://good-garage-guide.honestjohn.co. ... ering-ltd/

Ian,

A brief showing of the Transmission or Restricted Performance messages is often a by-product of another fault code that is thrown up by one of the sensors. I used to get it on my 350 when a MAF fault code threw up.

As Rob says, I would change the auto fluid anyway at that mileage and also get the car scanned for fault codes if you're not able to do it yourself. There are lots of places selling fluid and sump lits at really good prices. Battery voltage is critical but you wouldn't normally get that problem whilst travelling along (at 70mph!)

Good luck

Paul

Many thanks for that Paul,
He has the car booked in now and I've also impressed upon him the importance of a fluid change - I hope he acts now and gets to enjoy the car for many more years - I'll post back when the work is done.

Regards,
Ian

the other thing to check on 350 is the earthing pints behind the headlights, remove the plastic slam panel cover, and locate the two studs that hold all the earthing wires to the cars shell, this is a steel stud which reacts with the alloy (others will know the correct terms here), the stud falls of, or gives a poor earth prior to falling off, which in turn gives some seriously weird and wonderful electrical conditions, flashing headlights, handbrake failures, wipers with a mind of their own, both my 350's have had this failure, worth a check. Remake the earth with a new bolt through the front panel, job done,

Good info Rob.
Just checked mine. They looked ok, but the slightest turn on the Nut and they fell off. Are all the earth straps this flaky, or just these ones?

Definitely, the studs can sheer for a past time, Naki.

A classic case of the galloping Galvanics at their best...electrolytic corrosion having a chew at things. I drilled one broken alloy stud out and replaced it with a stainless 316 nut, washer and bolt.

Mike

... this is a steel stud which reacts with the alloy (others will know the correct terms here), the stud falls of, or gives a poor earth prior to falling off ...

... They looked ok, but the slightest turn on the Nut and they fell off. Are all the earth straps this flaky, or just these ones?

I think they are actually aluminium studs, with two resulting problems: you can't tighten them too much or they snap (6 ft-lb if I remember correctly) and they fatigue. To make matters worse, the ones at the front carry the headlamp earths, and early cars suffered problems with dim headlamps that could be cured by tightening the nuts.

Of course, no-one ever uses a torque screwdriver to check the torque, and of course whenever someone reported a problem with the headlights or similar, the first thing to try was tighten these nuts. Which means over-tighten, and the aluminium won't take it. In my case, it turned out the problem was the steering column switch, not the earth. I only found out about the condition of these studs when my wipers stopped parking, and tried to tighten the wrong stud, which immediately fell off.

Definitely, the studs can sheer for a past time, Naki.

A classic case of the galloping Galvanics at their best...electrolytic corrosion having a chew at things. I drilled one broken alloy stud out and replaced it with a stainless 316 nut, washer and bolt.

Mike

I just made a temporary fix for now.
Presumably the headlamps need to come out to drill the broken stud out? And does the bumper need to come off to get the headlamps out?

I replaced the broken stud on my car without bumper and headlight removal. Space for working a drill and hand tools is however somewhat tight.

Mike

I replaced the broken stud on my car without bumper and headlight removal. Space for working a drill and hand tools is however somewhat tight.

Mike

I didn’t see a direct drilling angle with the lamps in place. If I was to utilise the same stud location. Unless I drill at an angle?
There’s also a third stud much lower down behind the off side lamp. I did not touch this yet, since I could see the access was not there. Though of course I expect it will break the same as the upper two.

I can`t recall whether I came in from the front or back using a cordless drill driver but I drilled out the remains of the stud and was then left with just the thin aluminum structure. OK, my drilling may have been at an angle but it was of little consequence as all I needed was a clearance hole in which to site my new bolt. So bolt through hole, washer and nut, tighten, pile on the ground cables with new lug ends, another washer and nut and tighten up. Job done.

Mike