Went to start the car tonight and it turned over as usual
for a split second but then began to lose cranking power
quickly. The car did start (surprised). I measured ~9v at
across the battery with the engine running - the charging
gauge on the dash was clearly in the red zone.
So, I am thinking it is the alternator. I see a test
procedure in the manual - disconnect the big brown wire at
the alternator and measure amps. There is also a test for
the voltage regulator. I will attempt these when I can.
I was wondering if anyone had input on what to look for
during testing and if there are alternator replacement
options (besides a rebuilt exchange from one of the
usuals). I searched the archives and did not find much
(the possibility of a gm unit - which I still need to
investigate).
Any input is appreciated.
Thanks–
Vince, taking care of a 74 Series III OTS
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Vince3 sent Tue 16 Sep 2014:
Run the engine to 1500 RPM, and measure the voltage at the
alternator output. If it’s less than about 13.8V, then the
alternator is not working. It should read between 14.0 and
14.5V, more or less.–
Ray Livingston - '64 OTS Santa Cruz, CA
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Ray Livingston sent Tue 16 Sep 2014:
Just had similar issue with an earlier car, hopefully solved
by cleaning battery terminals inside, tightening
connections, checking ground connection and tightening belt.–
gar E
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Any local shop can rebuild the alternator, no need to pay
the jagsupplierpremium.
If you switch to another alternator, make sure it has an
omnidirectional fan or a fan suited to the rotation
direction in this application, alt is mounted ‘backwards’.
Or fit a standard modern alt where your air pump is/was.–
Dave S3E,RR SS, BMW’02,Tr4a,Elise, http://www.xketype.com
Georgetown, Penang, Malaysia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from David Lacey sent Wed 17 Sep 2014:
Visitor suggests.
Make a ‘‘patch cord’’ for the VOM. A spare charge outlet
that fits in the cigar receptacle is neat. Now, yuou can
measure voltage in real time under various load and rpm
conditions.
As far as I know, only an alternator for a GM Corvair
has fan/fins to go with a CCW rotation.
However, one can live with a conventional CW fan going
CCW. Not as efficient, but it will move air.
A CW fan can be made omnidirectional, by a plate on the
open end. I don’t quite get how this can draw air through
the alternator. Or push it through???
Pure spec. Flip the fan on the shaft!!!
Son’s SBC powered restified 60’s Chris Craft uses a CW
alternator going CCW. No issues???
Carl–
The original message included these comments:
If you switch to another alternator, make sure it has an
omnidirectional fan or a fan suited to the rotation
direction in this application, alt is mounted ‘backwards’.
Or fit a standard modern alt where your air pump is/was.
–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Vince3 sent Tue 16 Sep 2014:
I also have a 74. After I bought it nearly 20 years ago I
found that there was no voltage regulator though the
alternator looked identical to original equipment. At one
point I had to have it rewound, very reasonable, and the
tech said it was a more robust Leece-Neville model has an
internal regulator. Has been working great for many years.–
mollyoliver
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from mollyoliver sent Wed 17 Sep 2014:
Thanks for all your suggestions. Here is an update. I took
a quick look at the voltage regulator and the three wired
connector was barely attached. I removed it and noticed
the corrosion on all three spade connectors. I sanded
those clean and attached the connector (securely). I left
a trickle charger on the battery all night.
Today, I disconnected the two brown wires from the
alternator and measured volts at the alternator output.
Had my meter set at the 20 scale and got an solid 1-
reading? Moved the scale up to 200 and pulled 26-27
volts. I was not expecting that. Took a look at the
voltmeter on the dash as the car was warming up (wires
still disconnected) and the needed was moving to the middle
(acceptable) range.
I do not understand how that meter looks better with the
alternator totally disconnected. Is that just measuring
the state of the battery and not the effectiveness of the
charging system?
I put the brown wires back and took another voltage reading
at the alternator output. At 1500 rpm, I see 13.6. I am
getting a similar number across the battery. My dash gauge
needle is still where it should be.
So, at this point, unless 13.6 is unacceptable, I think I
might just have a battery that is on the way out. It is 3+
years old and is normally kept on a charger � but not last
week. I will try again over the next few days to see how
she does.
If it still turns out to be the alternator, I did find a
local shop that didn�t hesitate to fix it. If anyone is
considering a one wire alt upgrade, although not done on an
E, here is a thorough write up I stumbled into - on an
xj-s. http://bernardembden.com/xjs/altmove/
Thanks again–
Vince, taking care of a 74 Series III OTS
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–