Oops.

[MattP]

I am still working through some of the previous owner bugs on my B. The main one has been the alternator, well I found that the current owner can cause a few bugs himself.

I took the alternator to a local rebuilder, and he was very knoledgable about the Lucas products. As I was admiring his work, he asked, "You do know you shouldn't jumpstart British cars, don't you?" /ubbthreads/images/graemlins/blush.gif I do now. The first time the battery went bad I tried to jump it of the Escort. It didn't work, so I ran the battery back for replacement under warranty. Ran fine for a week or so, then kaput again. I pulled the alternator, took it in, and after the rebuild, he replaced all the electronic bits on the back. I guess that is how he knew. Live and learn. I just hope I didn't fry anything else in this lesson.

 

[Steve_S]

I've jump started british cars dozens of times without problem.

 

[MattP]

Really? I was wondering. I can see on one of the old positive earth, possibly, but I can't think of what it could have done to mine.

Any guesses?

 

[Steve_S]

I don't think it matters if it's positive or negative ground so long as you connect the batteries positive to positive and negative to negative.

 

[Dave Russell]

The "knowledgeable" rebuilder is wrong. Steve is correct. Just make sure that no metal parts of the cars are in contact with each other. Connecting a battery backward will blow the alternator diodes very quickly.
D

 

[Loaf]

When, you think about it, jump starting a car with correctly connected cables is absolutely identical to starting it normally. You're still applying 12 volts DC to the same leads that your own battery uses - what could possibly be harmful about that? I find the "Don't jump-start MGs" comment very odd, particularly coming from a guy who knows enough to rebuild an alternator...

If you can jump-start a modern car with all of its sensitive computer systems it's hard to see what would be so special about a primitive old MG! Perhaps the issue arises because of confusion about the negative earth/positive earth issue?

Loaf

 

[sparkydave]

I'm not sure where the idea that jump starting a British car is bad comes from either. Unless he was thinking of some older ones that still had 6-volt systems. Even when it comes to positive ground versus negative ground there isn't a problem, so long as you make sure they aren't touching and you make sure the polarities match, since the cable colors may not have the same convention. Even my '77 Midget with negative ground has the colors backward for some reason (black is positive).
-Dave

 

[Joe Reed]

He's probably seen a bunch where the person hooking up the cable doesn't look at the polarity on the battery - but just to see which one is the ground...

 

[MattP]

That is about what I was thinking. At least I don't feel like a nimnal thinking I fried my alternator. Not that I don't feel like a nimnal just for other reasons.