What a dumbass: Reversed jumper cables

[Porsche2112]

Hello I'm new here and afraid that I did some serious damage to my '79 911sc. I tried to jumpstart my 911 and accidentally reversed the cables. What I do know:

Cables from charging vehicle were on correctly
Cables to 911 reversed
Cables were likely reversed for at least 2-3 minutes
Saw light smoke coming out of fan blades (probably from the alternator)
After charging battery overnight - battery seems ok
Car cranks but will not fire
Any help would be greatly appreciated
Thanks, Larry Toporek GROSSE ILE, MI

[ppetion]

Assuming you have a CDI unit on your 79, that would be one thing to check. Smoke coming out of the alternator? You know what that means . You will have to replace it.

[RSBob]

Welcome to the community. You certainly know how to make an entry. Virtually everyone here has made dumbass mistakes and there are a couple of very long and amusing threads to prove it.

The best resource on the board, other than real time replies is Advanced Search. In the blue bar above select Search, then Advanced Search and then enter your criteria. For this issue I would look up look up reversed polarity, or fried alternator, battery backwards, etc. you will get a wealth of info.

[OldSpool87]

Oooof…good luck in straightening it all out. Before you get back to us though, be sure to drop you dip stick into your oil tank.

[DanielDudley]

Larry, you might want to find out if there are any air cooled Porsche people anywhere in your region. Maybe Porsche Club of America, or maybe fellow Pelicans from this board.

Also, see if you can find out who the local independent Porsche repair shops are, and who is well regarded. It never hurts to find out. The way I see it, the biggest problem you face right now is that the driving season is winding down, and you will feel rushed to get this sorted out.

Take a deep breath and relax. What man can build, man can fix.

[Porsche2112]

This is an incredible forum with so much valuable information Thanks for taking time to respond to my situation, I'm going remove the alternator, since it was smoking. Haven't located the CDI yet - is it on the distributor? New to 911's (I've owned a couple 356's) so I'm just trying to figure everything out.

"When in doubt X=8" author unknown

[lsf911]

Larry,

The CDI box is mounted to the inner drivers side rear quarter panel.
I have attached a picture of what a stock unit looks like.



I noticed Pelican offers a CDI rebuild service for $200 if you need to go that route.

[pors1968]

Make sure to disconnect the battery before to remove the alternator.It should be already disconnect

[timmy2]

Carefully inspect your engine harness from starter cable to the alternator. It is a direct non-fused connection from the battery to starter to alternator. May have seen a lot of current after burning up the diodes in the alternator....

[Joe Bob]

Check EVERYTHING electrical, including radio. I'm hoping you learned from this.....good luck.

[sugarwood]

Originally Posted by Porsche2112

"When in doubt X=8" author unknown

https://en.wikipedia.org/wiki/Phrases_from_The_Hitchhiker%27s_Guide_to_the_Galax y#Answer_to_the_Ultimate_Question_of_Life.2C_the_U niverse.2C_and_Everything_.2842.29

[gazzerr]

Yeah you trashed the diodes in the alternator for sure.

[porsche930dude]

Just thought id say id definately pull the gauges and have a good look at all the wiring behind and under the dash and everywhere else before you attempt to restart it. and consider adding fuses to the dash circuits. There is a thread somewhere on that

[RFP]

No, Larry, you are not a dumbass! You just made a mistake that a g'zillion other car owners have made, you just have a nicer car. As has already been pointed out, it's all fixable, and as you work through this 'speed bump' in your Porsche experience, you will wind up knowing a lot more about your Porsche than you do now. Take a deep breath, and be grateful there were no open flames involved in your learning experience.

Rob

[Porsche2112]

Didn't get very far today, I got called into work to make a couple welds on a high pressure steam main. I did locate the CDI mod. hopefully I can make something happen tomorrow.

[Joe Bob]

You can't FUBAR what is fried anymore already done....hook up the battery AFTER having it tested and then try out the electronics. Hopefully the battery and radio survived. The CDI should give out a high pitched whine. Ingo Schmitz 'iscmitz' rebuilds CDIs on an exchange basis.

[Porsche2112]

After speaking with the folks at Porsche-Rennstatt Arbormotion in Ann Arbor MI I've decided to have them do the repairs. I'm working 7 days a week 10-12 hours a day, I don't have time. This is an excellent Independent Shop and the owner, Tim Potts, happens to be Club Pres. of PCA Ralley Sport Region in Southeast MI.

[billybek]

Nice car, Larry!
Sometimes it makes more sense to call in a pro.
Hope it is nothing serious.
Welcome to the forum.