my 91 ranger the battery every 2 monthe corrodes so bad i cant start it! when i jump it runs and dies once i let off the gas. when i wire brush the terminal it runs fine. whats wrong with this? shouldnt the engine run on the alternator once the engine is on? and not on the battery?

 

I think the terminal corrosion and the stalling are two separate issues, but one may be contributing to the other.

In regard to the battery, if it is not a maintenance free battery, check the water level in each cell. If you have to top it off, only use distilled water. I have heard that low electrolyte will cause accelerated terminal corrosion. Next, clean the terminals again. Then apply an aerosol electrical contact cleaner to the terminals and ring lugs. Make sure that you use a cleaner that incorporates an oil or other compound that prevents corrosion.

As for the alternator (if that truely is the source of the stalling), it sounds like it's crapping out. If the alternator is not putting out enough current to run the ignition coil, the coil will draw current off the battery. When the battery no longer has any voltage, it cannot supply power to the ignition coil. The alternator itself may be letting go, or the rectifier on the alternator may be dieing. The rectifier "cleans up" the power from the alternator and keeps it at a more consistent voltage and current. There is no way to replace the rectifier, just have to do the entire alternator.

My first reccommendation would be to check the "eye" in the top of the battery, if equipped. If you see green, the battery is in good shape. If there is no green, the battery is shot. The next step would be to drive the truck to AutoZone and have them test the current and voltage output of the alternator. They'll know what the operating range is, and they will be able to tell you if you're out of that range.

Keep us posted...

 

pour coke all over the corrosion. it's an old beater trick..

 

Clean the terminals, clamps, and the battery itself really good. Reconnect it and make sure the clamps are good and tight. There is a terminal protector spray you can get and spray on the thing. It looks like red spraypaint when it comes out. It works quite well, we use it on all our fire trucks to prevent this.

If you still have problems with starting and stalling, have the battery and the alternator tested. Those eyes on the battery aren't worth crap, they always get stuck and mean nothing.

 

Try De-Ox on your terminals after you wire brush them really good. When I put my stereo in, I put some of that after brushing the terminals and putting my amp wire on. It works real good. You just have to worry about not hitting it with water when you pressure wash your engine

 

a friend of mine who is in college for auto-mechanics said that my alt was outputting too much power would this cause a problem

 

Umm. No. You'd see stuff smoking before you see crap on the battery terminals. Overvoltage would start smoking components and there is no such thing as outputting too many amps because amps are drawn, not pushed.

 

Sound like you need to get your alternator tested. You could possibly have a bad regulator and your brushes could be getting worn down too. Both of these are replaceable parts, well actually everything in the alternator is replaceable.
What I really need to know is when it won't start, have you cleaned the terminals before jumping or after?

 

i try to jump it and it dies so i then clean it once ts off

 

that sounds similar to problem my friend was having with his car it would die at idle or if he had his light on. His turned out to be the alternator. Like said before take it to autozone and have them test both the battery and alternator they can tell you if they are bad or not. If its the alternator some other places can tell you whats exactly not working right.