Alternator problems

[Duro5341]

Hey guys....

Well we are starting a winter storm up here, and there was about 4" of snow fell so far. One my way home tonight the alternator konked out 4 times.

Mostly as I was coming to a stop, the volts would drop right off to 12.6v, and when I reved it up it took about 7-8 seconds, and then the voltage was back up like it should be.

The alternator is about 1 year old, and the battery about the same. It has a 1000CCA battery, and the internal regulated alternator.

Recently today I backed the timing off to 7 degrees intial timing, and the idle back down to 700-750RPM..because I was having some problems with pinging when it was cold. Now I have never had this happen with this alternator, and there was alittle bit of snow that blew into the engine bay when it was parked for about 4 hours. The belt is tight, and not slipping.

I am wondering if the voltage regulator is on it's way out?. It's not like it was charging low....it just cut out completely, and everything whet really dim. I want to get this figured out, so I don't screw my good battery

Thanks
Duro

[shadetree]

In my opinion, your idle speed is a little low for all the stuff you have going. The alternator could be getting overwhelmed, and loosing its excited state. Try upping the idle speed & see if it isn't fixed.

[BLE 'BURBAN]

What accessories do you have on your vehicle? The more you have the higher output alternator you're going to need.
What is the output rating of your alternator? NAPA carries a 94 amp output alternator that is in the same case as the standard 63 amp model. I'll see if I can find the part number for it for you.
Whats the condition of your cables? They may look good but can have corrosion wicking down the inside of the insulation. They should be just as flexible to within 1.5" of the ends as they are in the middle of the cable. If not then they are begining to corode up on you and should be replaced.

the part number for the above mentioned alternator is......

RAYLOC #134352A

Attributes:
Features & Benefits:Bearings - 100% New
Premium Quality
Features & Benefits:Completely Remanufactured With The Most New Top Quality Parts Available
Features & Benefits:Computer Tested Under Loaded
On-Car Simulated Conditions
Features & Benefits:Electronics - Heavy Duty for Longer Service Life
Features & Benefits - 2:Brushes - 100% New
Premium Quality
Amp Rating:55-66 Amp
Clock Position:12:00
Type of Pulley:1 Groove
Type of Regulator:Internal

[AceX]

If you do get a new alternator, spend a couple extra bucks and get a high-output alternator (100-140amp). It's well worth it. Even though you may never use it to its capacity...

[old Rusty C10]

sounds like the regulator is starting to go . id change out the alternator just to be safe and like the others said id go for a higher amp one so that you can run more stuff and be safe

[Duro5341]

The truck is a custom deluxe. It has manual windows, locks, no A/C....only has power steering, and brakes.

The alternator is a 75amp, stock was a 63amp......

I think I may have found the ansewer, I will be staying late at work to trouble shoot it.....There are 3 or 4-red, 1-purple wires going down to the B terminal on the starter, and purple going to the S terminal, and it looks like one red one has lost it's insulation. It worked great today, until I hit a big puddle, and it dropped off again, for about 5 seconds. I will let it run, and start soaking down wires until my voltage drops

Does the red (charging output)wire off the alternator go down the B terminal on the starter?, I think it may be shorting out, and dropping all it's volts to the engine mount....thus dropping it's charging. Everything is stock on this truck, and original unmolested wiring aswell

Thanks
Duro

[old Rusty C10]

yeah a 75 amp should work ok in that as long as you dont have a radio that i could hear in the southern tier of NY State from Ontario... yes its possible your wiring harness could be the culprit particularly when that section gets wet.. but if at all possible id still check the alternator..

[454HO]

Originally Posted by Duro5341

Does the red (charging output)wire off the alternator go down the B terminal on the starter?

I'm not positive (no pun intended), but that does not sound right. Usually the alternator output either goes directly to the battery or to a power distribution block, which then goes directly to the battery. What year truck and what engine are we talking about here???

Oh, and FWIW on alternators... the rated output current should be acheivable at engine idle speed. That is assuming the pulleys are all stock (no 'power pulleys') and the engine idle speed is set per the manufacturers specs. If it cannot put out the rated current at idle, then the alternator is bad. Drive up to the local autoparts store and have them load test it on the truck.

Also, any time you put a higher capacity alternator on an engine you should also upgrade the charge wire to a larger gauge to handle the rated current. Otherwise you run the risk of an electrical fire and watching your truck go up in smoke.

[Duro5341]

Well it turns out the belt was slipping, however there was no squeling noise. When you sprayed the back of the Multi-rib belt with water the voltage dropped to 12.6v, then after 5-10 seconds (after it dried out) the voltage would go back up.

However this red wire does infact go the the distribution block, aswell as the charge wire for the alternator. It is one of the fuseable links. I put some wire loom around it for now, and will be calling GM tommorrow to get it replaced. I am amazed it didn't short out on the engine mount bracket.

I also figured out my pinging noise.......it says on the Emission sticker that I am supposed to run a minumum of 89 octane, and I was running 87 when my timing was set at 9 degrees. Now it is at 7 base timing.....with 89 octane....so all is well. Now on to the next project, tighten up the door latches. Does anyone know if there is any adjustment in these?

Duro

[Duro5341]

Originally Posted by old Rusty C10

yeah a 75 amp should work ok in that as long as you dont have a radio that i could hear in the southern tier of NY State from Ontario... yes its possible your wiring harness could be the culprit particularly when that section gets wet.. but if at all possible id still check the alternator..

Ya no huge stereo, the truck is original/unmolested. I replaced the factory AM, with a AM/FM from the same year.....so now I have STEREO out of one speaker

Duro