Alternator ground question

[prayers1 153]

Does the case of the alternator get grounded to the block

[LindenBruce 27]

Through the mounting system yes. But IIRC there is no wire running directly from the alternator to the engine block. There is a ground wire at the back of the alternator, but I believe it goes into the electrical harness. B.

[SA69mach 39]

Yes, via the mounting bolts.

[prayers1 153]

I have a 1/2" bolt on the back of the case. I was thinking of using a grounding strap and tying it to the head via an empty bolt hole.

 

Is that what I should do?

 

I'm using a GM alt and doing the one wire set up.

[THE EVIL TW1N 12]

I have a 1/2" bolt on the back of the case. I was thinking of using a grounding strap and tying it to the head via an empty bolt hole.

 

Is that what I should do?

 

I'm using a GM alt and doing the one wire set up.

 

Isn't the alternator case aluminum?

[prayers1 153]

Yes.

[LoneWolf2U 136]

Through the mounting system yes. But IIRC there is no wire running directly from the alternator to the engine block. There is a ground wire at the back of the alternator, but I believe it goes into the electrical harness. B.

 

There is a ring connector ground wire at the alt. It is from the charge loom and is bridged to a wire that goes to a ring connector at the block and appears as a loose ring connector at voltage reg plug.

FYI, having this connection in place helps with the lights dimming with engine rpm changes.

[THE EVIL TW1N 12]

Yes.

I was always told that aluminum is a poor conductor of electricity. But before I replied with that, I did my own research. Apparently, it's actually a pretty good/decent conductor. So I just learned something.

[RPM 1,190]

I was always told that aluminum is a poor conductor of electricity. But before I replied with that, I did my own research. Apparently, it's actually a pretty good/decent conductor. So I just learned something.

 

There is a lot of aluminum wiring used in construction.

 

Bob

[TexasEd 188]

I was always told that aluminum is a poor conductor of electricity. But before I replied with that, I did my own research. Apparently, it's actually a pretty good/decent conductor. So I just learned something.

 

It is until it oxidizes. If you have copper and aluminum touching it happens faster than like metals touching. Put some dielectric grease at the joints.

[Cruzzar 22]

If your brackets are powder coated be sure to run a ground wire from alternator to block.

[GypsyR 32]

I've "fixed" a couple of older Ford charging systems by simply running a ground wire from the stud on the back of the alternator case to the engine block. Even though anybody and everybody would think that being solidly bolted to the brackets and engine would make a fine ground. A little rust, oxidation, and/or paint can kill the connection. The cars I repaired already had new alternators, batteries, cables, etc but just wouldn't charge.

So it's my habit now to add a ground wire to the alternators of my personal vehicles if they don't have one. I have no doubt that you could do the same thing by cleaning all the connections at the bolts and brackets but I still add the wire.

[LindenBruce 27]

And don't forget the engine block to frame/body ground either. That will cause a lot of Gremlins as well. B.

[prayers1 153]

Ok, thanks for the reminder. I haven't done that yet.

 

On this project, I have taken the 289 and 4 speed out and replaced it with a 351C and an AOD trans. I'm getting close to start things up, maybe Monday and last night I found an extra ground strap wire and was wondering where I last placed it. Now you reminded me.

 

I have grounded from the block to the firewall, neg battery lead to the radiator support and alt. to block. Mach1Rider told me about the grounds on my first engine installment some time ago

 

Yes, you could never have enough ground contacts!

Edited June 8, 2014 by prayers1