After 4 months of my 4 litre being cooped up since lockdown, I decided that with the hottest day of the year expected on Friday, I would get her out of storage and head off to a quiet beach for a swim.

The battery had been on a conditioner throughout the the last 4 months, so with a quick tyre pressure check (all perfect!) and fluids checked, I started her up, put the roof down and headed off with daughter to a quiet shingle beach about 35 miles away. The voltmeter was reading relatively low at just over 13v but it has always slightly under-read against the actual charging voltage so I didn't think anything of it.

After a lovely couple of hours on the beach, we headed home, the voltage reading was slightly lower, but again the car ran fine.

On Saturday, I took the car up to a Mercedes showroom about 20 miles away to look at a car for a friend and now the voltmeter was reading about 11v and also the temp gauge and oil pressure gauges were reading low. I was now getting a little concerned.

As any facelift convertible owner will know, it's nigh-on impossible to see any of the warning lights with the roof down, as I suspect I would otherwise have noticed that the red charge light was on!

When I went to leave the Mercedes dealer, the car tried to turn over but not sufficient to start the car. I borrowed the dealer's boost pack and jumped the car and decided to try and drive home. Voltmeter was now sitting at the minimum 9v reading. Suffice to say that the car dropped into limp-home mode, managed a stuttering 15 miles and then gave up trying to manage the incline on the motorway. So, with the support of the AA, I arrived home on the back of a recovery truck! Changes in legislation meant that I had to travel in my own car on the low-loader with ignition off and seatbelt on! I also found that I was fruitlessly pressing my own brake pedal going into some of the bends!

Once the car was back at home and offloaded, I checked the battery voltage directly and it read 11.7v which seemed quite high not to be able to run the ignition and fire the injectors?

After a charge-up of the battery and restart of the car, today it seems the alternator is not producing any charge, so tomorrow I'll take it off and pop it into a guy I know who rebuilds alternators and starter motors. I know the alternator has never been changed in the life of the car so I can hardly complain.

Does anyone know a simple way of testing the rectifier pack so I can understand if that's the problem?

Moral of the story - don't leave an XJS for 4 months without driving it. I really should know better!

Paul

 

It's an easy job to swap out the diode pack.
Lots of how-to vids on YouTube
https://www.maniacelectricmotors.com/77904018.html

 

Is this diode pack different from the brush and regulator combo of some alternators? My alternator stopped it's charging some time ago and haven't removed it yet.

 

Yes, it's a different part. In my case the bearings, brushes, etc. all were good. Just some bad diodes. That's usually what goes bad on them.

 

Sounds like you had more fun than you bargained for. Awesome! Keep having fun, next time will be even better, with a bit constant dash monitoring of course

 

Paul
The ignominy of it! Which sadly I shared. A couple of weeks ago we drove down to a large city for the day. 4.30 pm back in the car park, flat battery. I have carried jump leads in their box since I bought the car in 1998; at last they were used!.
Happens to us all unless we are prepared to renew stuff a la aircraft industry, on an hours/years basis, regardless of whether it is broken or not.

How is the pre-HE progessing?

 

Hi Paul

Replacing a Diode Pack is pretty simple (even I can do it!) No Soldering required

The question is how hard it would be to get the Plastic Cover off the back of the Alternator or else take it out of the Car

As a matter of interest since I cancelled my Breakdown Insurance, how long did your Rescue Service take to turn up?

And if its any Consolation, which it is probably not

You didn't Break Down 'Your Car Just Failed To Proceed'



Typical Generic Alternator Diode Pack

 

This morning I decided to do some tests on the alternator to see if I could better pinpoint the problem.

I started by doing a simple diode check. Although I had no reason to suspect a parasitic drain, it's a simple check to perform. The test showed about 530mv with the negative probe on the B+ terminal with zero / overload when reversed, so that seemed fine.

With the engine running, I was only reading battery voltage of 12.8v when measured directly off the back of the alternator, so I decided it might well be a rectifier issue. With no apparent output current, I wasn't sure how I could check the regulator was functioning correctly, so I decided to take the alternator out.

Although removal from a 4 litre AJ16 is much easier than on a V12, Jaguar still conspired to make some things difficult for owners!

With the Air Filter and trunking removed, top access is fairly easy. However, removal of any of the nuts and bolts is a nuisance. And all of them will be tight!









I started by disconnecting the battery and removing the wiring connections.

I then loosened the lower lock nut on the adjustment arm. And that in itself is a pain to get at cleanly with a spanner! But with that eventually slackened off, I then slackened the adjustment arm mount bolt and then removed the trunnion bolt attaching the adjustment arm to the alternator. I then raised the car and started on the alternator lower pivot bracket bolt. And of course Jaguar designed it so you can't easily get to the back end nut without an offset spanner. And then the alternator belt and the fan try and stop you getting a socket on the front end of the bolt head. Don't believe the apparent clear access in the pic below! They are a pain to get at!!



Eventually they were loosened and removed.





A little bit of leverage with a pry bar and I moved the alternator out of its pivot bracket. It was then fairly easy to remove it from above.





Once out, I checked the front bearing which seemed very smooth. I then removed the back cover and checked the brush which seemed fine.







I have a very good auto-electrical specialist near to me so decided to drop the unit in there. I've asked them to confirm that there's no bearing play when run up to speed, check the rectifier pack and regulator and let me know how much to sort the problem. Weirdly, on the counter in front of me were 2 absolutely identical Denso alternators, apparently out of kit racing cars, that had just been dropped off by a customer for servicing. Coincidence or what?!

As I will change the belt whilst the alternator is out, it's a good time to also take off my aircon compressor and belt and put on the new compressor that I bought last year and still haven't fitted! And of course, I can probably find some other jobs to do whilst I'm in there!



To be continued...

 

Following as I have zero output at the moment. This happened last year after I washed the engine down. Coincidence? Now the engine and bay are clean but no worky alternator.

 

Tks Greg,

I did miss out one bit of the original story!

I used to always carry jump leads in every car, but these days I carry one of those 1000a peak power mini power packs. They are awesome and can start my Range Rover quite easily,

BUT...because I'd swapped over cars to go the beach, I forgot to transfer over the power pack which might have JUST had sufficient power to have started the XJS and got me home if id connected it up and left it turned on?

When I realised the power pack wasn't in the car, I thought "bugger!" But not to worry, I'll just ring daughter and get her to drive up to meet me with the power pack that I'd bought for her. So, she duly arrived only for me to find out that she hadn't bother keeping her power pack charged up because of course, her Mini never goes wrong! So, that's why I ended up sending her home and calling the AA Breakdown service!!

And because I hadn't been down to my storage unit during the recent troubled times, I haven't done anything further to the pre-HE. So now I have 2 non-functioning XJSs!!

Que Sera...

Paul

 

OB,

Tks also for your thoughts. The good news was that because the AA sometimes use local recovery agents if they know the car is going to be recovered rather than fixed, then the low-loader was with me within 50 mins of me ringing. The driver was good, asking me if I had any preference as to how the winch cable should be attached. I decided to use the lashing eye at the front. Overall, I was pleased that I'd renewed my policy, especially as I've never called them out previously in 23 years of membership, so I'm always thinking of not bothering to renew it!

Paul

 

That must be a very strange experience.

There are worse places to breakdown. This was 1200 miles from home and 700 miles from our destination:




Like you, I was very pleased I'd paid for breakdown and recovery cover for many years.

Graham

 

Come on Graham, what went wrong?

 

After travelling from home in the north of England, crossing the English Channel via Eurotunnel, covering the length of France and crossing the Pyrenees into Spain (1126 miles/1812 Km) in 19 hours, I'd just refuelled again and the car went into restricted performance. Out with my laptop and Jaguar SDD at the roadside, diagnostics confirmed a failed injector. Crawled the near 100 miles to our overnight hotel and then began negotiating recovery/repair.

The car was taken to the Jaguar Dealer in Burgos for repair and we were given a rental to make our way the 500 miles/800 km to our destination in the south of Spain. Before leaving, I had a session with the dealer Tech. Both he and the Service Manager seemed surprised to find an owner with his own Jaguar diagnostics and to see my saved session from the roadside exactly matched their own in the workshop.

Three days later the injector had arrived from Jaguar and been fitted. I made the 1000 mile/1600 km) round trip to return the rental and collect the Jaguar by myself. An XK with no passenger or luggage and only two speed cameras on the entire route is a very fast way to travel.

Graham

 

I was an AA member for many years but have used Britannia Rescue for several years as they are more competitive for International recovery.

Your experience drew my attention to an article about the AA on the BBC website this morning. I hadn't realised the AA is a staggering £2.65bn in debt! Those familiar yellow vans and recovery vehicles could soon disappear if they come to agreement with one of three potential buyers.

Graham

 

Most likely a result of a leveraged buy-out; whereby in effect, the purchase price of a business is raised by borrowings the business itself makes as soon as it is bought by the incoming management. Of course, a disgraceful way to effectively asset strip a business leaving it vulnerable to any sort of downturn in trade, as all the financial resilience has been removed. Not illegal, but it should be.
The same family of disgraceful management as is practised by a HUGE number of stock exchange quoted companies, whereby the company borrows money, buys its own shares, this raises the share price, and the management sell their optioned shares at a huge profit. In effect the company is borrowing to give the management money. Again, not illegal; but it should be.
As a financial system, the West has asked for its own destruction by such shenanigans.
/rant over.

 

As some of you may already know, I took out Breakdown Insurance and then Cancelled it again, during their 'Cooling Off Period' because the last thing that I wanted was a Rescue Service turning up, with a £200 Fuel Pump! if that went wrong on my Car

Then just guess what happened!

My Fuel Pump went wrong, not on my XJS (as could have happened) but on my 'Daily Driver' where I would have also been Covered by the same Breakdown Insurance

All it took was One Phone Call and the GF called a Mate out to come and Rescue me and get me home, where Plan 'B' would have been to call a local Recovery Service, who would have recovered the Car for £75 as I had already got a quote just in Case my Mate was unavailable

Having got the Car home, the Firm that I bought the Fuel Pump from, replaced it FOC as it was still under Guarantee and so as soon as I put that on then I was back in business and also bought a Spare Fuel Pump to Carry in the Jag, which I could change by the side of the road in under 30 minutes

And so for me Breakdown Insurance just did not seem worth it, as it was something that I've always managed to do without, at least up to now!

 

For me it depends on distance. If anything happens within about 50 miles of home, sorting it out myself would probably be quicker and almost certainly cheaper. The difficult situation in the UK would be a motorway breakdown which has fortunately never happened to me.

However, I have recovery insurance mainly for Continental cover as a breakdown in mainland Europe is never a straightforward experience and can be extremely expensive without appropriate cover.

In the last 25 years I've made 36 Continental tours totalling 526 days out of the UK and covering 87,810 miles in France, Spain, Portugal, Italy and Switzerland. In that time I've had 2 breakdowns. The one described above and a burst cooling hose on an XJ40. The XJ40 breakdown was on a Christmas Day afternoon in Amiens, northern France 70 miles away from our rented house. Difficult to think of a worse possible time for a breakdown but a recovery vehicle arrived in under 2 hours, took us back to the house and the car to safe storage until the garages opened after the holiday.

Both of these experiences were very expensive but breakdown insurance covered everything except labour and parts costs. More importantly, the insurer arranged everything and kept me informed throughout the process.

Graham

 

Part 2………



I had taken the troublesome alternator into South Eastern Auto Electrical Services in Maidstone, Kent. Steve from SEAS rang me the next day and advised me that the bearings and brush were good, as I expected, but that at least one of the diodes in the voltage rectifier had failed and that the voltage regulator also needed replacing. I agreed that they should complete the job, as it seemed a false economy for me to collect the unit, buy the parts and do the job myself. Two days later, I picked up my shiny alternator.





The discolouration of part of the rectifier pack seems to give a clue as to at least one faulty diode.



I thought the alternator would go back in without trouble but how wrong was I!

The pivot bracket has a bush inserted at the forward end. I thought I could just gently tap the alternator into the pivot bracket. “ Gently” soon became “Firmly” which soon became “Determinedly”!



In retrospect, and even with the limited space available, I should have tried to drift the bush out a bit before trying to install the alternator, but rather foolishly I persevered with my stubborn approach. And because I had another car parked on the ramp above, every time I jacked the car up to work on manipulating the alternator from below, I then couldn’t open the bonnet to work from above! So not only was I repeatedly jacking and lowering the car, even when I eventually thought I’d got the unit aligned inside the pivot bracket, I then found that it has to be PERFECTLY aligned in order for the bolt to slide through! So followed 2 hours of trying to insert screwdrivers, tapered drifts and every other bit of long thin metal that I could find in my garage to get the alignment perfect. And the proximity of the radiator means that it's almost impossible to insert any thing longer than about 5 inches into the pivot bracket hole. Lying on my back with hugely restricted access above, it was a hugely difficult task!

FINALLY, the bolt could be inserted from the front and with some gentle ratcheting so as not to damage the threads, I managed to wind it through the rear of the bracket. It had taken a total of 5 hours for something that should have taken 5 minutes!



After a beer to cheer myself up, I then fitted a new belt, set the tension adjustment rod, tightened the pivot bolt, refitted the electrical leads, started the car and watched as my voltmeter now read 14+ volts! Another beer followed in short order!



So, Lessons learnt:

It’s definitely worth considering a rebuild or partial rebuild of your alternator rather than the expensive cost of a replacement Denso unit or the dubious quality of the Chinese copy units currently on the market. After 25 years, my bearing had no play and the brush was fine. The expected failure points on these units always seem to be the rectifiers and the regulators. Even using an external company I only paid £115 for the work which including cleaning the casing and painting the end cover.

Unless your alternator just falls out of the pivot bracket (it won’t!), try and drift back the packing bush at the front end, before refitting the unit. You’ll be pleased you did!

Now, on to the aircon compressor.....

Paul

 

Off topic, I see you have fitted a block heater. Do you use it much? I didn't think it got very cold in England, comparatively, speaking as a Canadian! That also looks like the 120V cord, where do you plug it in?