sblev

I have a 1991 Mustang LX, I'm the second owner. I bought it used from a lot in California in 1993. It's a great car, but for most of it's existence it's been doing something strange, and no one has been able to figure out why. We've had it in many repair shops, including dealerships and no one can discover the fix.

It eats batteries. We have to replace them on an average of every 3 years. We've had the alternator replaced, wiring checked, and a number of other searches and repairs done, but we can't find out why. And the real problem is that sometimes the battery will be drained even while driving, so that when we stop, the car won't start again!

Here are the clues: While driving, the temperature gauge will rise until it's topped out, while the battery indicator drops until it bottoms out! But if you stop the car and check under the hood, you can tell the engine is not overheating at all. Finally, the "check battery" symbol starts flashing under the speedometer. When that starts, we know we're running on borrowed time. But then, for no apparent the reason the gauges will suddenly return to normal.

There must be someone out there with a real feel for cars who can figure this out. Is it you?

It's occurred to me that somehow the gauges themselves might be the cause of the problem. What do you think?


Thanks for reading my post,
Steve

PRO50SC

I would start by checking ALL the grounds on the car. A bad connection can cause all sorts of problems. As far as the batteries go, does the car sit for long periods of time then needing a jump or a charge to get going? If that's the case, batteries constantly being drained over time shortens the life of the battery considerably. I've run into that myself over the years.

nitrous_bob

i would ditch the underdrive pullies if it in fact has them. and if you replaced the alt, w/out replacing the pulley if was an underdrive setup, you will be over revving the alt, possibly causing a charging problem , smaller crank pulley , and need a bigger alt pulley

easiest way to tell, look at the crank pully.....if it's the same diameter(about) as the damper, you have ud's

if it's about 1" larger radius....it's stock.

Twisted

Have you put a meter on the battery with the car running to see what kind of voltage the alt is putting out. I don't know whether they do or don't, but if these cars have a voltage regulator separate from the alternator, you might suspect it if the battery is overcharging.