Ground Wire and Alternator?

I don't know about that... the alternator should get its primary ground from the mounting hardware (which is direct to the frame).

-- JimG

80' CJ-7 258 CID 35" BFG MT on 15x10 Centerlines D44 Rear, Dana 30 Front. SOA 4.56 Gears, LockRight F&R Dana 300 w/4:1 & Currie twin sticks Warn X8000i w/ dual batteries

JimG did pass the time by typing:

Alternator is direct to the engine block. Engine block is isolated from the frame via the rubber engine mounts. If the ground strap between the engine and frame is corroded the engine will not have a ground.

Silly me. I forgot all about those rubber mounts. I'll run some new grounds tomorrow. I think 10 gauge will work for the alternator to frame/body. I'd use bigger, but thats all I have available right now.

Doug you are correct... I should have said block, which is then connected directly to the battery ground via a 4 AWG cable.

JimG

You should have a 4-6 AWG from the block to the battery. A 10 AWG (good for ~40 amps) would be OK temporarily.

JimG

connection?

L.W. (ßill) Hughes III did pass the time by typing:

Personally, I dislike braided copper because it corrodes internally. For lighting protection they actually discourage its use.

I found a good engine ground can be made from battery cable. Just leave a bit of slack (say a 4" loop) and it's good for a long time.

JimG did pass the time by typing:

I missed one thing. The engine may get a round-about ground through the transmission links and drive train. But it's gonna be real wonky.

Usually it just seeks ground through the sensor wires and causes all sorts of hell with the computer. That's why a jumper between the engine and frame is a good first check for any rough running engine.

"wonky"... I will look that one up in the NEC. :-)

Your points are well taken.

JimG

Maybe I didn't state it well. I need a wire from the alternator to the frame or body. The connection is good from the block to the battery from what my fluke meter shows. Hopefully getting all the grounding issues resolved will keep my alternator running cool and not smokin hot.

Don't take the meter reading too seriously - a few milliohms at 10s of amps is a whole different ball game than what the meter measures. The problem with meters is that even badly corroded connection will have tiny low impedance punch thru points which the meter reads a OK - these disappear when several amps hit the joint. One decent test is just a plain old hand - if the connection is warm to the touch, it's corroded. One common error is measuring from the cable clamp to the block - measure from the actual battery post to catch a bad battery clamp. The meter will also no catch a loose connection.

Just as a side note: I just replaced my alternator with one from Advanced Auto (a rebuilt unit) and when I first put it in, it got so hot that it started smoking! I later learned that they are not designed to charge a dead battery, so I used a charger on the batteries overnight and its been fine now for about a month. I really don't think frame and body grounding will cause an alternator to get hot... the negative side of the charge path should be from the block to the battery. Frame/body grounds are for lights/electronics.

JimG

Is the contact shaky between the alternator and block? If so, the alternator needs it's own ground. Otherwise likely the ground you need is from the block to the fender.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Paul Brogren wrote:

Hi Jim, From reading a post a couple weeks back, maybe yours. Anyways, I did charge the battery up before installing the alternator.

To Will and Mike, I think I'll just start replacing both the engine to battery grounds and alternator to fender ground. They have a little surface corrosion that I couldn't see well with a flash light yesterday evening.

Thanks All, Paul

And if it works, please buy the NAPA counter guy some donuts and coffee. Helpful advice should be rewarded if it was offered free.

Knowing Paul is a cheap bastard and all, I'd bet that he tried to do some sort of shifty trade deal with Bubba down at NAPA. Probably trade some of his kid's toys, or his dog's collar. He can't slip out of that AutoZone type of mentality.

I visited Paul last summer. We took his CJ, with the pink letter tires, up this big ass mountain. It took all day.. We drank expired beer on the way up the mountain, of which Paul scored at some discount booze store down in Denver. We must've bought about 7 cases of swill, dirt cheap. I wasn't sure of what he was trading with them at the time, but with him, it could've been anything, if you know what I mean.

He sure is a shifty old bastard.

Amber Alert, Matt is a master of disguise. Armed with his Trench coat, Tu Tu,and ripple wine he's a trooper. He can be found frequenting various I-94 off ramps in the Ann Arbor, MI. region. Use caution, he a wolf in sheeps clothing.