Mike Gayner

I'm just getting ready to fire up my new engine but when I connect the battery there is an obvious short somewhere - the terminals try to weld themselves to the battery. This is an old car (1972 XA Falcon) and has had alot of dodgy work done on it in the past, which I'm slowly tidying up. The wiring is an absolute mess and there are bugger all fuses. From what I can tell all of the positive wiring goes through the starter motor as the big starter + cable is the only cable that goes to the battery. How can I locate the short? Is it possible I stuffed up the wiring for the alternator and this is what's causing it? Please help me, I'm desperate! Really want this thing going today as it's my ride to work tomorrow!

Edit- Just found that if I unplug the alternator (I set up a plug for the 3 wires to the alt for ease of removal/fitting) then the short doesn't occur - what else comes off the alt wiring?

brenx

The alt wiring (thick black with yellow strip or plain yellow wire) runs directly to your ignition and either you starter or battery. Your short maybe be at the start motor. The wires can easily twist when tightening them.

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XB Fairmont (street car) 11.07@123.02mph.

Mike Gayner

Just checked that, the starter wiring is fine. This car doesn't have very much of its original colored wiring unfortunately. Is it possible I connected the alternator with the wrong polarity? I've tried reversing the wires and it still shorts but maybe the damage has been done already so it will short both ways? I don't know, I'm really clutching for straws here.

I've found that the short will occur when both the starter and alternator are hooked up, but if I disconnect either one of them it's fine. Don't know if this helps to narrow it down but I'm pretty desperate.

xrgt

Mike,

As the alternator is grounded...(-) you need to make sure any positive (+) wires connected to/from it are not touching it's housing, otherwise it will short and burn/fry some wires if not start a fire!. Check these connections and make sure there is a plastic or rubber washer behind those circle crimp wires on the alternator.

hope this helps...and good luck

Mike Gayner

Mate you might just have it - there is no insulating washer between the eyelet terminal and the alternator - how stupid!! Then again, almost all electrical faults seem stupid after you figure it out. I'll find a plastic washer and get back to you.

brenx

That was ny next suggestion. I've done the same on a 1.3lt motor when I was servicing it. Had me stuffed. Always the simple stuff.

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XB Fairmont (street car) 11.07@123.02mph.

Mike Gayner

Yup that certainly was the problem, I appreciate your help guys. Was just about to fire it up but the battery is flat so I'll charge it over night and probably start the engine tomorrow arvo. I'm so nervous I'm actually really reluctant to start it - if I've done one little thing wrong I could be $2000+ out of pocket, which to me is bloody heaps, as I earn sweet f*ck all.

brenx

Pissing money into the wind always hurts. No matter how much you earn. Just make sure you have oil pressure and you'll be fine.

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XB Fairmont (street car) 11.07@123.02mph.

Mike Gayner

I don't have an oil pressure guage - should I rely on the idiot light, or buy a cheapo guage tomorrow?

TruBlu351

As long as your idiot light works you should be OK. I think they're set to go out above 15psi.

I would still get an actual oil pressure gauge though. Whether you get it tomorrow or some other time when funds allow. You can then see whats normal and identify any abnormalities before they get bad.

Watch out for your alternator light going out when you start your car. You may have blown some of the diodes due to incorrect polarity on the casing etc, inwhich case it won't generate a charge.

Good luck with everything. I hope you're up and down the street destroying some ozone tomorrow

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XE Falcon
393 Tremec TKO 9"