1 wire Alternator gets super hot!

[j286]

I have a 1970 c10 just recently rewired everything with American autowire 21 circuits harness. I started with a 3 wire 100 amp alternator from Amazon, it was getting extremely hot so I traced out all wiring couldn't find any problems so I assumed I just had a cheap alternator. I replaced it with a 1 wire 100 amp from summit and I'm having the same issue with the new one. Does anyone have any ideas?

[AussieinNC]

The alternator needs a good clean ground path back to the battery,,,,make sure the bracket the alt is bolted to has a clean surface where it meets the alt...plus the bracket to engine and engine to battery and chassis

You cannot have too many ground straps on these trucks....

Engine to chassis
Trans to chassis
Bed to chassis
Cab to chassis
Dash to cab
Radiator support to cab

The ground lead from Negative battery terminal should be direct to the engine, then ground straps engine to chassis and trans to chassis....

Finally, a one wire alternator does not need the voltage regulator...check the woring guide that came with the alternator....

[Duck 37]

Make sure it is grounded well

[AussieinNC]

Hey duck...got ya by a minute...

[Red71gmc]

Subscribed

[j286]

I have a strap from the engine to the frame,battery to frame and from the little ground tab on the alternator to the frame. I also grinded each surface to the metal before installing the grounds.

[AussieinNC]

Add a large ground lead direct battery to engine....

[j286]

I will add a large ground from the battery directly to engine. Thanks for the replies.

[OregonNed]

Originally Posted by j286

I have a strap from the engine to the frame,battery to frame and from the little ground tab on the alternator to the frame. I also grinded each surface to the metal before installing the grounds.

I did the same when I upgraded my alternator.. good grounds throughout

[68is4me]

How hot is hot? 120 degrees to the touch of the hand can seem hot. Do you have any big loads that are making iy charge at max?

[Steeveedee]

Do you have a volt meter or ammeter to check the performance?

[j286]

I added a heavy ground from the battery which I have relocated to underneath the bed floor to a junction block on the frame right beside the motor. Then I added a 4 gauge wire from there to the engine,firewall, and core support. Alternator is still getting hot after idling for less than 5 minutes. Any other ideas?

[j286]

It is putting out 14.38 volts at idle. It has dual electric fans and Dual air compressors for air ride. I currently have the fuse pulled on the air compressor so the electric fans should be the biggest load.no a/c or sound system.

[Steeveedee]

That is a reasonable voltage, which would indicate that the system is charging normally. Do you have gauges in the truck? If so, how far to the right is the needle into the "Charge" side? Barring any other evidence, maybe find someone else with a truck equipped like yours and get a hands-on feel for comparison. The only other thing I can think of is bad bearings, but two in a row is extremely unlikely.

[j286]

I tried removing the hot wire from the alternator and it runs ice cold, so bearings are good. It gets so hot u can't touch it.

[kazoocruiser]

What kind of terminal ends are on your cables? If they are replacement bolt- ons, they could be corroded or the cable wires could be carrying too much internal resistance.

I didn't see it from the posts, so I'll throw this in here. Have you done any testing on the battery to make sure you don't have a weak cell in it? A good battery carries 12.6. A bad battery may show that, but if you turn the headlights on, and any other loads with the engine off, and wait, you should only see it drop to maybe 12.3. If you disconnect the electrical feed to the distributor and crank the engine around for 30 seconds, that should really drag any surface voltage off the battery and give you an idea of true condition. If you end up showing 10-11 volts after doing your tests and letting the battery sit for a bit to recover, the battery is weak and is making the alternator compensate and that will generate extra heat.

The other thing you didn't mention is what your battery is showing when you have the engine running. I didn't see any discussion about your routing of your positive wiring. You probably should go back with your multi-meter set on ohms and check for excessive resistance in the wires, both negative and positive circuits. Take the battery out of the circuit while testing.

Excessive resistance in the positive side will cause excessive heat in the charging circuit.

[68is4me]

Sounds like it is working like it should. Not sure how hot they should run but I am almost sure that they will be hot to the touch. Thats why they put the cooling fan and heat sinks to try to cool them down. The faster your rpms go the more air movement though the alt.

[j286]

The terminal ends are crimped and soldered everything is new and clean. I done a voltage drop test on positive and negative while the truck was running and everything checkes out good. I also ohmed each wire from end to end both checked out good. The battery is at 12.6 not running, when I turn on the headlights and fans it drops to 12.1 with both air compressor it drops to 11.7. When its running that battery holds at about 14.1.

The wiring on the positive side is a 2 gauge from the battery to the starter and from there its 6 gauge to the alternator and a 6 gauge going into the cab.

[kwmech]

So the charging wire is at the starter?

[j286]

Yes that is correct. Is this not good?

[kwmech]

Not that it will hurt anything so to speak, but personally I would have run it directly to the battery. I always install the Ford style remote solenoid and just run the batt. cable down to the starter with a jumper to the S.

[Ruscal]

Another note: Make sure to run a proper fan behind your alternator pulley to move air thru your alternator.
Russ

[kazoocruiser]

Originally Posted by j286

It is putting out 14.38 volts at idle. It has dual electric fans and Dual air compressors for air ride. I currently have the fuse pulled on the air compressor so the electric fans should be the biggest load.no a/c or sound system.

I noticed you also said "When its running that battery holds at about 14.1."

That shows a red flag to me. You should have the same voltage showing at the B+ output of the alternator at the positive terminal of the battery connection.

I'd try disconnecting the negative terminal, and with the engine off, use your ohm meter to test the entire length of positive from alternator B+ post to battery. Any resistance in the circuit will give you a problem.

Maybe you might want to double check your readings with a different meter. Sometimes they go out of calibration, or the battery inside it might be weak.

[j286]

I'm going to run a new positive wire from the battery to the alternator instead of having it junction at the starter. I will definitely try another meter,that makes sense they should be the same.

I have 2 different fans for my alternator. Does anyone know which would be the best to use?

[AussieinNC]

A standard Alternator fan has at least 10 or 11 fan blades...

Yours has 8....

Use the fan with the highest number of blades...