Today I took my '71 Jag Lump with 383 V8/200R on a local 25 trip to watch my grandson play ice hockey... they won in the last ten seconds! After lunch with the family, I started the drive home on the freeway. The engine and alternator have been in the car since 1997.. only recent electrical work has been the driving lights and the electronic heater valve (replacement). Those are still working properly and have their own fuses.

About 10 miles from home, with no AC or heat on, the radio started cutting in and out and the car started running rough off and on... I switched gas tanks as that is one of the more common Jag problems...

Scanning the gauges I noticed the Battery gauge was below mid position so I turned on the live data screen provided by the EFI system... it confirmed battery voltage was at 11.7V or the same as the Jag gauge. Everything else was working fine and EFI takes good proper voltages...

I drove the rest of the way to my off ramp and hit a red light at the first intersection.. the car died.. then white smoke started coming out of the left side of the hood... I got out and opened the hood.. no fire but lots of smoke and the charging wire on the alternator was lying on the left hand valve cover. Alternator is/was 140 AMP unit that was installed brand new and has never
given me any trouble before this day...

That charging wire is totally burnt from the alternator to the LH firewall post.. that appears to be all that is destroyed? The bolt and nut holding the wire is still connected but the piece it was attached to on the alternator is "broken" off and still bolted to the wire - see the photos. The remnants of the wire cover (Red) is shown in the photos.

Three young men helped me push the car out of the intersection to a parking lot... I called AAA for a tow home.

All the things on the car work, clock, radio, windows and lights and even the new driving lights. I am sure it would start after charging the battery and will try tomorrow.

My opinion is the alternator failed internally - dead shorted to the post and fried the wire.. am looking for other possibilities and things to check. I have never seen one do that before and cannot understand how that large connection piece under the bolt/nut is not still attached to the alternator???

 

Wow, I think you have a short some where after the alt. If the alt shorted internally it wouldn't have effected the wire that much. Since the whole wire is burnt up. I'd examine the 2 bulk head pass throughs which is where that alt wire should bolt to. Should be easy to find using a test lamp. This reminds me that the Alt wire should have a fuseable link. My lump doesn't have one now... but will be getting one on the battery side and the alt side of the bulk heads this week.

 

I agree that the "+" posts on the firewall are worth checking. Perhaps one came loose and is no longer isolated from the body?

I'd open up the alternator for a look-see, just on GPs

Cheers
DD

 

Will add one when I figure out the cause of the problem... that charging wire only goes to the left hand firewall post... the problems begins or ends there...
not sure what happened - yet.

My thoughts:

With only the charging wire being fried... how can there be a problem "after the alternator"? Everything else still works and no fuses are blown...

Will check both posts... but they and the attaching wires have not been messed with for years...I took them apart early on to clean things to get around
any potential problems.

I do plan to look in the alternator and will have a good local shop do so as well. I need to know why that attaching point for the charging wire is not still attached to the alternator. I believe Powermaster makes the alternators sold by Vintage Age and will contact them as well... someone else must have had a similar problem at some other time.

 

Oh...you're suggesting that the alternator shorted to ground and energy from the battery which should have a heavier cable fried the alternator wire. I guess that's plausible too now that I think about it. Those GM alternators do have a rather flimsy bushing that isolates the case. I guess it's possible that bushing failed from vibration or some other cause.

 

I think I am on to it. An internal diode failure. Or as ISO suggest.


In my theory, When the rpm's went down at the red light, the battery + on the firewall shorted to the alternator. The big brown was the weakest link and fried.


So:


1. Do a battery drain test. VOM between the battery - post and ground. With all loads off, as you know, only a few milliamps should show. More means a short somewhere. But, not in the alternator as it is not connected.


2. It seems that a mechanical flaw in the alternator Is limited. it turns
and doesn't kill a belt.


3. Electrical flaw. Most likely. VOM battery + to + post on the alternator. Should be 0 ! if any flow/short the issue is there.
Off with it and back to the vendor !!!


Carl

 

They volunteered to look at it for me... good company. Will arrive in Texas on Monday... hope it is a internal short.. if not I will have a big problem figuring out the source of the problem.

Only time they have seen anything like this was when someone use too small of a gauge wire for the charging wire. Mine was 6 gauge and the wire length is only 4 feet. No need for a fusible link as the wire acts as one already!

Firewall posts are fine... all the stuff connected to the other post still works and the two posts are connected together by a larger gauge wire.

The last portion of the wire was wrapped with other wires going in the direction of the firewall post... will check all of them inch per inch today for any damage.

 

On the trail of it. Alternator or merely the wire from it to the firewall post. A is the leading suspect, huh!!


Carl

 

I do not know what the metal post looked like before the "problem"... the thickness of the metal section still attached to the burned up charging makes it look "substantial".

Have no idea how it attached inside the alternator either.... Vintage Air says Tuff Stuff makes their alternators... will have to look for some internal photos...
it had not been off the alternator since the installation in 2008... no reason as it all worked perfectly.

The only wire that was damaged (insulation burned off) goes to the brake switch to disengage the OD trans when locked up.. it will be replaced tomorrow.

This time that one charging wire will be by itself all the way to the charging post on the firewall.. instead we bundled it up with premium wire wrap material for "good looks" last time.. not this time!

Just hope they find it shorted internally and I will replace it and go on.. I do hope Mr. Murphy will find another home...

 

I zoomed in on the wire connection at the alternator. My vote for "cause and origin".
A term used by firemen and those in my former profession. Case to post insulator failure. Opined by another as well.


Suspense. What will Vintage and Tuff say? What will they do about it!!! Read Roger's next episode.


Yeah, bundles look neat. But, there is a peril. Might be a place for a fusible link? But, as stated, the wire did that.


Not to be cynical. But, although, I am generally an optimist, I have a cynical side.
my codicil to Murphy's Law. "And, once having gone wrong, will remain so".
But, laws including codicils are breached each and every day !!!! A take off from contract law.


Again. Only inconvenience and extra work. No real damage to property ands no one hurt. And, you got home!!!


Tale from the past. School chum, Roy, bought a back row 29 Ford A coupe. Sixty bucks as I recall. Scruffy, but it ran fairly well. Plans to make it an open car for kid adventures. He about 19, at the time. I, a year younger. We cut off the top, tossed the fenders and running boards. Time to go rabbit hunting at night. Still on skinny tires, 19's or even 21's. I standing and shooting over the windshield. Roy driving. On the chase of a Jack. Pow, the head lights went dark!!! Crept home on the beam of a flash light!!


Necropsy. Head light switch fed direct from the out put side of the generator "cut off relay. Battery not in the loop to smooth out the voltage spikes. Roy, talented in electronics, under stood this. I not so much. Roy went on to Ford aeronautics, a rocket scientist.


Carl


Carl

 

They had never seen one do that before, it is now part of their Heritage Wall of Racing ..... like my Wall of Shame... bent 440 Dodge rod and piston, bad fuel filter, burned up electric fan fuse etc...

They are selling me a replacement alternator at dealer cost and this alternator was purchased in 2004, installed in 2007 and I started using it in 2008.. has maybe 10K miles on it now..

That is how great companies warranty their old models that have been updated to better connections... they told me the new one will have a different charging wire connection.. will wait to get a new wire until I have it in my hands...

What a great DAY!

 

That's Great, Roger!
I have been following this thread (quite interesting), as I have had alternators bite the dust before but it was usually a diode; one ran so long on the farm that the bearings went and the rotor dragged on the stator.

It's good to have a happy ending!
(';')

 

Wow what a great company! To warranty to any extent an alternator that's twelve yrs old is unheard of.

 

It is all back on the Jaguar and will go out soon and hook up the fully charged battery.... then will see what happens? The one valve cover shown has small burn marks on the top edge and will remove it and see they can be polished out.

After confirming no problems will try to start it up again. The one wire that got destroyed because it was close to the charging wire went to the Tach. The tach on a Series 1 is needed to be there or jumped or it will not run... my idea of the rough running before it finally fried and died due to low voltage..

With good luck it will be fine again and I can wrap the old wires again (I have moved them from being close to the charging wire near the rear of the engine to well behind the distributor))... then onto to finishing up the restoration... only have new front door panels to replace due to the new S3 arm rests and a couple of other trim things left.

 

That's Great, Roger!
As I mentioned, I've been following this thread with great interest, and I like your new battery cable! You certainly shouldn't have any trouble with that!

In fact, I may use that idea, because one of my projects this winter is to upgrade my headlights as it's Really Dark out here in the Stix and I like to see what's jumping out in front of me.
(';')

 

It started on the first turn of the key and ran well.. I did get half the old wiring rewrapped yesterday. Will finish it up today and go for long local drive.

Tuff Stuff claims a lot of amps available at idle speed and the idle voltage is nice and stable (140 AMP alternator with one wire) and regular seven inch lights are working great.. even with them on and with the new Cibie driving lights on there is no reduction of lights.

Pictures show 14.1-14.2V at idle on the EZ-EFI tablet (and the Jag gauge) along with the other selected engine information... it is just laying along side the shifter for this photo...tablet hooks to a GPS style mounting ball... normally it is just hanging out of the parcel tray next to the two vents in the center.

 

Roger:


Indeed, very sanitary and functional. Sophisticated electronics as well!!! Kudos.


My simpler version uses my HF VOM with patch cord to the lighter receptacle to read volts in real time and under various loads and rpm's.


My volts are supplied be 140 amp Delco that came with my LT1 package. So fspo good.


My alternator is off the left side of the engine. So, my "big" wire detours to the wing wall and thence back to the post by the battery. Just because after market harness came that way!!


I do like those Adel clamps. I use 4 to support the bracket I made support the PCM from the wing braces.


Elinor:


Yeah, as to "plumb wore out" alternators, I've been there. Way back when, dear departed and I purchased a very nice "low mileage" 65 Corvair Monza coupe. Off the Chevvy dealer's used lot. Ellen and the stick shift 63 did not get along. The 65 featured two speed Powerglide.


Many oddities that countered the "low mileage" thing. The alternator was charging, but making noises. I took it apart. Wow, as you say.... Swapped it for a rebuild.


Carl

 

Corvair epilog. After a lot of fixing and swapping, I concluded that the car was indeed a low mileage unit, but a very well used transaxle and engine had been swapped in!!!!.


I got 'snookered", or did we ?? Ellen and I got a lot more miles out of it before selling it as a "project".


Carl

 

I drove the car around town today and all is well.

The wiring is all wrapped an secured away from the new charging wire.

Back to normal now... only a few more things to do and they include new front door panels and some interior trim work.!