Hi everyone, this is Donna, I have been away alot over some serious health problems, and want to apologize if I left anyone's messages or tech help unanswered.
I have missed talking to many of you I have gotten to know.
Anyways,I think my alternator is on it's way out.i had taken it for a 150 kilometer run, it all worked fine. Then I started it the next day and went to the store and it began to rain and snow. I stopped three times. When I first started the car and warmed it up it was fine. So I got to my destination shut the car off, came back out and started it up and noticed the battery/alternator light was on! I just got going and the indicator light went back to normal. Then I made my last stop at another store, after I was done in the store, I came back and started the car, this time the light would'nt go out. So I went straight home about 7 minutes from the store.
The next day(today) I started the car up. And the light would not go out, and the battery light showed it was in the red, and not charging.
For the last two weeks I noticed a weird whining sound, but strangely enough it would only whine when in gear, but would NOT WHINE IN NEUTRAL
Last week I heard a whining noise like bearings or something.
What else whines only in gear, but the whining stops IN NEUTRAL? Somebody mentioned that the starter relay has a wire that goes to the alternator and if the starter relay not good it screws with the alternator, this makes no sense m, it is just something I read what they said.

 

Welcome back to the forums Donna,

I've moved your question from General Tech Help to XJS forum. This is a better location for seeking opinions and advice on the whining.

Graham

 

Donna,
It may be the alternator, it has worked hard for a good many years.

BUT

It may be the battery, oldish, and not taking a proper charge.

Being a 1988, the belt that drives the alternator is the last one off, convenient, not.

1) However, the "V" pulley on the crankshaft that drives that belt, is vulcanised to the main pack, and that vulcanising is well known to "de-laminate" with age, and prevent the alternator spinning as it should to do its task.

2) Whine./squeal as the rubber stuff is torn up in the process.

Steps to check for me would be:

A volt meter across the battery with the engine running, should show 14.2V or thereabouts. This means the alternator is in fact working.
Check the belt itself, loose, or maybe missing.
Check the "V" pulley, for slippage of the rubber laminate. Paint mark across the 2 sections, run the engine with lights etc ON, and then shut it down and note if the paint line is still a single line, or staggered. Staggered is de-lamination.

The only electrical connection between the starter and the alternator is the LARGE battery cable that travels from the starter solenoid to the alternator +ve post/s. Nothing there will mess with either part.

ALSO.

Check the main engine strap/s, there are 2 that traverse the LH engine mount bracketry. They do fail, break, work loose, generally play up, and that will reek havoc with engine electrical items.

AND

Get yourself well, the car will wait, they are like that.


1)

 

Thank you Graham.

 

It is likely one of two things. The brushes in the voltage regulator are worn out in the alternator and it isn't changing anymore. If you have more than 150,000 km on that car that is certainly a possibility. It's not too bad to change the voltage regulator in car.

Possibility 2: The belt for the alternator is driven off the outer ring of the crankshaft damper. The steel pulley that drives the alternator belt is bonded to a rubber section, which is also bonded to a centre steel piece to make a sandwich. With time and heat, the rubber becomes hard and bond breaks. The the outer steel ring slips on the rubber and can't drive the alternator. To test for this possibility, take a white paint marker and put a radial line from the centre section to the outer ring. You'll probably have to do it from under the car to gain access. Start and drive the car a few times and then check the marks. If they are no longer aligned, then you have a bad crankshaft damper.

Not as likely possibility 3: The belt has inadequate tension to drive the alternator. Check it with the proper gauge and bring to spec (No, a thumb isn't the proper gauge!)

 

Where the hell am I supposed to reply? It keeps saying my reply is too short!

 

I checked the belts, they are good. I noticed the plug has oil all over it, oil is NOT a good conductor of electricity. I dont understand how the engine mount has anything to do with the electrical? Because it throws the belts out alignnent?
I will check the engine mount and clean the plug to the alt, but this is a rebuilt alt that was put in three years ago. I can't remember if it was a 115 amp Bosch, or 75 amp Lucas. Either way it is a pain in the *** with @$$hole neighbours bitching that I started my car at 7 PM lastnight. So tonight I started it at 6 PM, and if it was HIS car he would start it any time he wanted and wouldn't tolerate people coming over to his garage bitching at him! The real problem is not the noise the car makes....IT'S THE FACT THAT IT IS NOT HIS CAR!!! This whiner comes over bitching about my car, then says how beautiful the car is and offered to buy it twice then insults me by saying he will get MY CAR for $6000. It told him I wouldn't sell it to him for $25,000! He says that's what he thought I would say!
So I have to work at this over days instead of hours because this jealous neighbour cant tolerate listening to a car he wants but can't have for himself!

 

There is a ground strap around the engine mount, that makes the negative side of the connection to the body. It spans the rubber in the motor mount.

Looks like 88 was a changeover year, could be either amperage.

 

To Grant’s note about the expected voltage at the battery. Mine never produced 14V at the battery, even with fresh battery. I typically get 13.5 - 13.7V

it works fine for me. Just wanted to provide an extra data point...

 

Ok, I will check that out. Now it makes sense.

 

Thank you!

 

13.6+ is deemed OK., on the later cars I am led to believe, as there was a change to the circuitry about 1988ish. Load dump module rings a bell.

My '85 runs a 110amp Bosch (XJ40 unit), and has 14.2-3 straight after start up, and settles at around 13.8/9 after about 30 minutes, and never drops below 13.2 at idle with all sorts of electrical stuff on.

Mind you, my wiring is new, and the earths are more in number than the factory by a very long stretch.

 

[QUOTE=Jagboi64;2146921]There is a ground strap around the engine mount, that makes the negative side of the connection to the body. It spans the rubber in the motor mount.

Looks like 88 was a changeover year, could be either

I think I found the alternator ground, it is a small black wire with an ,"O" ring on the end, and is bolted to the car. It is covered in oil! I am going to move the air pump out of the way and be in grease up to my elbows! The connections on the back of the alt are dirty too, don't know why, I don't drive the car on gravel roads and wait til they sweep the streets before I pull the car outa the garbage. I will let everyone know how it all turns out so that if anyone else gas a problem they may be helped! Here's crossing my fingers,!

 

The alternator is a rebuilt one put in about 4 years ago. The original alt got full of oil and had to be replaced. Let me explain.....there is a rubber plug at the front of the engine block. It is a access point to get at the timing chains. The rubber plug deteriorated and oil from the chains flipped oil all over my alternator and wrecked it! (Oil is not a good conductor of electricity...Haha!) So anybody with an older car should check the condition of that rubber plug at the front of the engine block, if it is hard and crumbling, it needs to be replaced, or you might end up like I did-buying a new alternator!

The belts were all new as well. And appear to be the right tension. But the plugs at the back of the alternator are dirty with sand an tranny fluid. The bozos who installed my new all aluminum radiator cut my metal lines to the to the tranny snow I harubbb

 

[QUOTE=Jagboi64;2146903]It is likely one of two things. The brushes in the voltage regulator are worn out in the alternator and it isn't changing anymore. If you have more than 150,000 km on that car that is certainly a possibility. It's not too bad to change the voltage regulator in car.

Possibility 2: The belt for the alternator is driven off the outer ring of the crankshaft damper. The steel pulley that drives the alternator belt is bonded to a rubber section, which is also bonded to a centre steel piece to make a sandwich. With time and heat, the rubber becomes hard and bond breaks. The the outer steel ring slips on the rubber and can't drive the alternator. To test for this possibility, take a white paint marker and put a radial line from the centre section to the outer ring. You'll probably have to do it from under the car to gain access. Start and drive the car a few times and then check the marks. If they are no longer aligned, then you have a bad crankshaft damper.

Not as likely possibility 3: The belt has inadequate tension to drive the alternator. Check it with the proper gauge and bring to spec (No, a thumb isn't the proper gauge!)[/QUOTE

I cant find my ramp I build out of three staggered 2x10's so cant crawl under the car right now. I used jumper cables and the alternator reads normal with the jumper cables on. Then I put a freshly charged battery in the car and immediately the alt reading dropped. So the best I can do us clean the ground wire and connection on the alt, if that does not cure it, this cat is off to the British veterinarian for a new alt! Poor kitty!

 

A fully charged battery wont get me around the parking lot......so all I can do is clean the plugs and ground wire and see if that helps.
It's weird, one day it was fine, i drove it 150 km, the next day it just quit working! That will suck if it need another alternator!
And I can't find the wooden ramps I built out of 2x10's, I laid Them on top of one another and nailed each one 6 inches from the edge from each one underneath.....

 

Hi.....still not quite well enough to wrench and tinker much on the old cat.
When I take the car out on the highway at higher speeds the battery light goes out and then back on then the tachometer jumps around wildly tempoearily. I can drive it for about an hour stop and go before I have to put it back on the charger.
I got the original car manual and I will look for the V pulley as you mentioned.
It sounds like bearings, but it would be hard for anyone else to isolate the sound as I have 2.5 inch side exit straight pipes with no cats, no mufflers except a straight thru MagnaFlow "muffer" just to make it "civil" enough for my ears!
I bought a really good charger which also tests the alternator, but haven't got the time to **** around as I am packing and moving.
I charged the battery to 100% then left it sit for awhile. Then drove to the corner store and the battery said 70%....**** me off!
I usually unplug the cables from the battery because if I leave the battery cables on it drains the battery. I can't figure out where the electrical draw is that drains the battery!
A former mechanic mentioned it could be the computer in the trunk!!...BUT he knows NOTHING about the V12 Jaguars so I think he's got rocks in his head.
One question, it was fine the night before I took it 150 kilometers, then the next day was the first time the battery light came on!
Do alternators just die suddenly, and temporarily come back to life at higher speeds?
Well I got alot to do so be back later.
When I get caught up financially from this co-vid **** I will take it yo my mechanic.
Co-vid is deliberately hyphenated to keep yhus message from appearing in google's search engine for this near fake *** virus.
They were testing for 4 strains of this virus in November 2018 when I was diagnosed with the H1N1 influenza....nasty flu, I was sick for 6 weeks on steroid inhalers, 2 rounds of antibiotics and two rounds of antiviral drugs....and coughed continually for the entire 6 weeks.
So I don't buy all the bullcrap with the
masks and lockdowns!

 

It could also be the harmonic balancer. Take a piece of chalk or some white-out and make a line from the inner hub through the rubber ring and to the outer ring. Start the car and drive it for a while. Then check and see if the chalk still lines up. If not, you need to replace or rebuild the balancer.