I've been looking at buying a nice 86 Jag from a coworker,its in great physical condition with only minor little scrapes on a few spots.
I've been driving it around for almost 2 weeks now {no money has changed hands yet} to get to and from work and around town.

it makes some little noises,the gas pedal makes a "click-click-click" sound sometimes and I get a warning about "anti lock failure" on the dash also. It runs fine and smooth and feels solid,no issues until yesterday.
The car had sat for two months and had a dead battery.We charged it,put some gas and power steering fluid in {I'm sure it needs more than that,but as I haven't decided to bu it yet I don't want to invest much } and it was fine.
Then yesterday it died on me after starting up {fyi it is very cold here right now}
The battery died on me later that night.I had someone charge it,then when i went around the corner to the gas station,it died again and needed another charge!

Someone told me its the alternator and maybe get a new battery also,then another than i just need to let it sit on a charger for a while longer.
Any thoughts? suggestions? tips ? it would be much appreciated.

 

86 with Antilock? Something is amiss if its a US car. Perhaps is an 88 XJ40?


Seem like you need to grab a volt meter and make sure you have 13.8 to 14.4v at the battery at idle.


In any case if an alternator with a bad diode will kill the battery even when at resest. The alternator winding will be segmented and each segment will have a diode. If the alternator's rotor happens to come to rest on the segment with the bad diode it will drain the battery.


Also ABS computer are very sensitive to transient current. If the alternator has a bad diode it will put out noisy voltage and they can confuse the ABS computer.


So you have two symptoms that could point to an electrical system issue. I'd remove the alternator and have it bench tested straight away.

 

Charge up the battery AFTER disconnecting the 2 alternator wires (or at least the main wire and ISOLATING it so it does not ground).

If its a bad alternator, it should start and run for a while without it - the battery won't get charged, but it should drop voltage very gradually without any lights or other power consumers on. Check voltage with VM

Also check if the alternator wire is shorting out somewhere. That's what I had, and consequently the alt went bad

 

The only Series 3 cars with anti-lock brakes were the V12s built after the six cylinder cars stopped production in 1986. Unless somebody has done a retro-fit

 

Cripes, so my 88 XJ12 has the antilock brakes? The same ones that the xjs guys moan about? How do I tell for sure without standing on the brake pedal ?

 

No.

The very last cars did....the last few hundred maybe? Circa 1991-1992? If the battery is in the boot, you have ABS. The battery was moved to make room the the ABS 'stuff'.

Cheers
DD

 

Make that April 1987, Fraser, for the last of the Ser III six cylinder cars



Cheers
DD

 

Whew, battery is upfront, that's a relief!

I've read enough horror stories on that ABS.