my 87 na kills batteries!!!

Hi all, my 87 kills brand new batteries in about a week or so.
I'm not sure why this happens but I'm pretty sure its a bad ground or short somewhere. The insulator cap on the alternator is broken at the top and I'm wondering if that may be causing it. I replaced the alternator when the old one killed the battery and bought a new battery but now it wont hold a charge. I broke the cap while I was reinstalling the new alternator. Does this make sense? Any help would be greatly appreciated.

That brown cap is only there to stop a lot of water or a random metal tool from shorting it out. To be safe go to a junk yard and pull one off almost any Toyota for free. Is everything else electrical working fine? The car runs and drives great, but when sitting for time it just drains the battery?

Shorts can be a very tricky thing to track down sometimes. What I would do is unhook the + side of the battery, put a volt/ohm meter between the + terminal and the + wire and measure the amperage passing through. Then with someone watching the meter start pulling fuses from the kickpanel fuse box and engine bay fuse box until you find the one that stops the current draw. That should narrow it down atleast.

Thanx for the info. Yea it runs pretty good except for the knock, but other than that it runs fine. I was affraid u were gonna say to pull the fuses with the voltmeter lol. The battery gets alot of corrosion on it to. I replaced the battery cables with gold plated ones( I think it's gold lol)
and even put those red and green cloth o-rings on them when I replaced the battery the third time and it still got corrosion. Crazy azz car, lol. I'll try that and see what I get. Thanx again.

Corrosion on the terminals is a simple fix. A mix of arm & hammer and water should solve it for quite a while. Might help to wire brush or lightly sand them first too.