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Old 10-01-2006, 07:37 PM
78novaman's Avatar
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Replaced Brushes & replaced battery terminals

The other day when checking the fluids on the car (1997 Mercury Cougar XR7, 4.6L, v8) I noticed some corrosion on the battery terminal. I've only been measuring 14.05v at the battery upon startup at idle and about 13.75v once warmed up. I figure this is a good time to replace the connector, fix the negative side that I hastily fixed up a few months ago, and also check the alternator and figure out why it's making a terrible whining noise and low voltage under load.

Always remove the negative cable from the battery before working on any electronics!

Here you can see the corrosion on the positive terminal:

The belt is easy to take off on this car, just use a 1/2Ē breaker bar, push the tensioner down and slip the belt off:

Take the time to inspect the belt for cracks or fraying, idler pulley, and tensioner for bearing noise while you have the belt loose. Mine are in good shape.

Don't be like me and drop the nut! I was luck it went into the lifter valley!

Look how dirty the back of the voltage regulator is!

Four torx screws hold the voltage regulator and the brushes. Then it pops out as a unit. My commutators were fine, and the inside wasn't the dirty.

The real problem were the brushes. Look at all the corrosion EEK!

The brushes are just screwed to the voltage regulator, here is what the new brushes from NAPA look like vs. the old ones:

I cleaned up the voltage regulator with Non-residue electrical contact cleaner and re-assembled the piece:

I then blew out the alternator with compressed air to get all the dirt out. Then I doused it in the same Non-residue electrical contact cleaner, a bit of nasty gunk came out. Blew it out again with compressed air as we don't want an engine fire when I start the car. Look how clean we are now:

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Old 10-01-2006, 07:39 PM
78novaman's Avatar
The AMC, FORD, & CHEVY Guy??!!
Last wiki edit: Improving fuel economy
Last journal entry: Finally on the road
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I then installed the now clean alternator back into the car. Now to tackle that pesky corrosion. I made a solution of 2 tablespoons of baking soda & a quart of water. I poured that right on the terminal and let it bubble to remove the corrosion. After a minute I rinsed it off with regular tap water. I then let it dry off. I came back and sprayed both battery terminals with Non-residue contact cleaner to remove whatever was left of the corrosion.
Now take a battery terminal cleaner and clean the posts off, leaving a nice shiny, conductive friendly surface:

Since my battery terminals were no good, I bought 2 cheapie ones at the parts store. I normally wouldn't recommend them, but I have a surprise at the end.

Cut the wire back so you have all decent wire exposed. Cut the insulation back so that you have just enough to crimp or clamp down so that there is no exposed wire to corrode. Crimp the wires down hard so there is no play, making a good mechanical connection.

Now I did an old school trick that an old car mechanic told me: solder the cable to the terminal. No iron will ever get the heavy of a cable or terminal hot enough to solder. Thus I used a propane torch to solder with.

WARNING: You have to be EXTREMELY careful with flame in the engine compartment! There are a lot of fluids and greases just waiting to catch on fire. I had my girlfriend stand by with water in case anything were to happen. I take no responsibility if you screw this up. Also REMOVE the BATTERY so it doesn't explode in your face. This will also give you room to work.

After you have a good mechanical connection, heat up the terminal to the point where you can melt solder on it without melting the lead terminal itself. Flow or wick the solder up the copper wire without directly using the flame to do so.

I put some dielectric grease on the base of the terminals and then anti-corrosion felt pieces under under the terminals.

I fired it up and we got 14.36v at idle under load. Check out how professional and clean it looks:

Then I finished it off with some more dielectric grease to keep the corrosion down. If you don't have any you can use Vaseline, it does the same thing.

I had it load tested at auto zombie and I get 13.76v under a 100amp load. I'm going to be updating the electrical system by using relays for the headlights and electric fan. Then that ugly power cable will be gone. I just have to gather the fuse link, a buss, and some more heavy gauge wire.

Last edited by 78novaman; 10-01-2006 at 07:44 PM.
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