OK, this is embarrassing. My "new" '67 just arrived with a dead battery (was trucked from 1500 miles away). A friend was kind enough (ha) to help with the jump box as I sat in the driver's seat waiting for the connection to be made. When he said it was ready, I turned the key and nothing happened...well, not nothing...the wires at the alternator started to smoke. Immediately turned off the key and pulled the jumper box...he had hooked it up backwards (positive to negative, negative to positive). Almost stroked out. I have peeled back the black plastic electric wrap about 6" to where there was no more burned wiring and repaired the damage and now when jumping off everything seems to be fine. New battery ordered (this one is shot) BUT my question. What else could have fried in the 3-5 seconds the key was turned on?? I don't want this car to go up in flames. I will be taking it to my mechanic but I would like some feedback from y'alls knowledge.thanks for not laughing too loud.
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Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star Regional -
Re: STUPID mistake!!
I did that to a Volvo years ago. Killed the alternator.
If the radio was on you could have hurt that.
Rich1966 L79 Convertible. Milano Maroon
1968 L71 Coupe. Rally Red (Sold 6/21)
1963 Corvair Monza Convertible -
Re: STUPID mistake!!
92 Toyota MR2… I had to work pretty hard to connect the battery after I put it in backwards! Did it in the Sears parking lot, had a pretty bad headache and shouldn't have been changing the battery. Don't feel so bad, we all make mistakes.Comment
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Re: STUPID mistake!!
Could have killed the diodes in the alternator. That is where the current went when you fried the wiring. But if you say everything works, then you probably got it in time and are good to go.
-Dan-Comment
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Re: STUPID mistake!!
will thoroughly check everything once the new battery is installed. Thanks for input and understanding...a true brain fart!!Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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Re: STUPID mistake!!
check the wiper motor, its hot all the time wokr off a grounded circut.Comment
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Re: STUPID mistake!!
I never, never, ever let anyone hook up cable to my car, I do it and check both to be sure, then I crank. I would even double check my best friend if he was helping. Hope everything is ok and no hidden damage.Michael
70 Mulsanne Blue LT-1
03 Electron Blue Z06Comment
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Re: STUPID mistake!!
Leif, Its not the end of the world, But a s Dan has eluded to, the diodes have likely taken the hit of the crossed cable connections, What the diodes do is permit voltage flow in one direction, So when the cables were crossed the voltage back up from alternator into the harness and melted the red battery wire. Do a close visual inspection of the harness in the engine bay, sometimes it will melt other wires together hopefully you did catch it in time before other damage was done, if you did, cut the melted wire out and replace with the same gauge wire and re-tape harness.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: STUPID mistake!!
Ed and Dan,Changing out the diode trio fairly straightforward? If so, may do that as a safety precaution anyways.Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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Re: STUPID mistake!!
When hit with a extra high current diodes quite often blow open rather than short as the high current melts the bonding wires within the diode. If one or two diodes go open the alternator will still work, but at reduced charging capacity as one or two of the 3 phases is no longer connected. The person usually does not know this, as it still works some, but with reduced charging capacity.
If the diodes are hit with a extra high voltage (not your case) then the common failure mode is the junction within the diode 'punches through', and the shorts the diode. When this happens the alternator does not work, or puts a constant drain on the battery.
But neither of these two scenarios are bible. Anything can happen. To be on the safe side change out the diodes. There are 2 sets of 3. 1 series set and one shunt set. For judging I'm not sure if replacement diodes will have the same markings as the originals. I will leave that to members that have more experience in this than me.
-Dan-Comment
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Re: STUPID mistake!!
Will do, Dan...thanks.Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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Re: STUPID mistake!!
More than likely didnt hurt a thing. Just try the new battery first.Comment
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Re: STUPID mistake!!
Probably very true. You could have the alternator tested. Most shops or suppliers can do this.
But on the other hand, the diodes are 50 years old. 50 years ago high current diodes had only been available for a few years, and the processes for making them have been greatly improved since then. 50 years of high temperature, vibration, and the stress that was imposed on them when you reversed the polarity could have weakened them. They will probably work, but if you want insurance against a latent failure, then replace them. There is no way of telling if their life expectancy has been shortened.
-Dan-Comment
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Re: STUPID mistake!!
Dan and Wayne,
This car is a two year old body off resto with a NOS date stamped alternator. I think I'll take it to a local shop and have it checked before going any further. I will, also, completely check the engine harness from end to end.
Thanks to all for comments and helpful tips. Been a couple of restless nights since this FUBAR!! New battery supposed to be here today...Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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