I have a 1969 olds cutlass with AC and 350 engine. My alternator/external regulator are no longer charging battery. I am not sure which part failed. I see battery voltage level only with car is off or running. I think I want to change to an internal regulated alternator. I am aware of the wiring changes to make but am looking for information on what alternator to buy (part number).

 

You'll receive several to many good recommendations. Firstly, a little more data would assist in diagnostics to ensure the steering committee can assist you're heading down a good path.

(1) What is the measured DC voltage at the battery w/ car OFF not running?
(2) What is the measured DC voltage at the battery w/ car ON & running at idle w/ all accessories turned OFF?
(3) What is the measured DC voltage at the battery w/ car ON & running at ~2,000 RPM w/: (a) all accessories turned OFF & (b) all accessories turned ON (accessories = AC, headlamps, radio, etc.)?
(4) Do you have a need to increase ALT amperage rating based on any additional aftermarket accessories i.e. stereo amplifiers come to mind?
(5) Is the currently installed ALT & VR OEM equipment? What amperage/model number if known?

 

Your local auto parts store can test the alternator.

 

And the regulator

 

When it failed, I saw the same voltage at the battery and alternator connection when the car was running, ~11.6.
The generator light did not come on.
I don't know yet if they are OEM parts.
I am presently not running any extra electronics.
Based on documentation it should be 55 amp.
I will pull both parts and get them tested later today.
If I stay with external regulator, is it better to get solid state one?
If I decide to go with internal regulator, is they a part number you recommend?

 

Eventually you'll get around to reviewing what has been posted to this thread. This topic appears often & as you can imagine has some dependency on model & year of production. I haven't changed an external to internal VR ALT for a 1969, others have. To assist, finding the correct information can be cumbersome. Most of us review many threads gaining information along the way. In the meantime, as you garner more information, here's a decent thread specific to a 1969 Cutlass you might find informative.

EDIT: Our paths crossed (in timing) as I was formulating this post response & just noticed you responded.

1969 Cutlass S 350 internal reg alternator

 

I would not say it’s better, they both do the same job but in different ways.

My experience is the mechanical regulators are more durable than the solid state ones, and the mechanical ones can be repaired whereas the solid state ones cannot - at least I have not found a way yet. I repaired my original mechanical regulator back in the 90s and it’s still working well.

 

I have removed alternator and regulator. Both are Delco parts but don`t see any numbers.
The regulator has the tab bend up on the blue wire?? Don't seem correct. This is my first time looking at these parts. Not sure why its bend up. Any thoughts?

 

Alternator fails and 4 different places could not test regulator.

 

So, you know you have a failed/bad ALT. At this point is a functioning or non-functioning VR of importance? I'll hedge to suggest the VR is likely OK & the issue resides w/ the ALT. To that end, you're going to require a new/rebuilt ALT. So (I think) the pressing decision remains external or internal ALT? You're going to require one or the other, right?

 

You are correct.
Think I am going rebuilt internal from rock auto
ACDELCO 3342189 Gold; Remanufactured; 78 AMP
$48

 

Here is an article I wrote on how to check your charging system.
Joe

 

I know this thread is almost a year old, but the information given here has been invaluable in helping me through my first major charging system problem and I just want to say thank you to Joe, Norm and everyone else. Joe, your PDF has been especially helpful so I want to give it a plug to those who may have similar problems in the future.

My '69 Cutlass S convertible (350 w/AC) has a one-year-old battery. Last week it started draining for no obvious reason. The charging system is an AC Delco 10DN 55 amp alternator with external voltage regulator. Cutting to the chase, the alternator's bad so I'm upgrading to a 12SI, 94 amp AC Delco 3342305. Once it arrives, I'll bypass the voltage regulator, add 8-gauge wiring where necessary, etc. as described here and in similar topics.

My car is very stock and I like it that way. I thought about the 10SI since it looks similar to the 10DN, but once I read that the 12SI delivers a lot more output at idle/low speeds I was sold. Living in LA, being able to run AC at night, in traffic, without having my lights dim is appealing. I don't know that I need 94 amps as opposed to 78, but as long as I need to put in 8-gauge wire anyway, why not? I might as well plan for the future.

I ran all the DC voltage checks mentioned here and followed all the steps in Joe's PDF until I got to the following:Reinstall the alternator plug and leave the regulator plug disconnected. With a voltmeter, check voltage at the number 3 terminal on the regulator plug, it should read battery voltage. There should not be any voltage at the other three terminals at this time. If you have voltage at the number 2 terminal, R on the alternator, you have a leaky diode in the alternator, replace the alternator.
Voltage at #2 terminal was 3.3V. The voltage regulator itself had so much rust and corrosion that I decided a replacement 10DN alternator, even with a replacement solid-state voltage regulator, just wasn't worth the hassle.

The one thing I can say to new people who'll come after me: I cannot stress enough the importance of cleaning old electrical contacts. Anytime you find them, clean them. Clean the grounds. If they're wires clean them. If the part grounds directly to the chassis, clean the part, bolts, nuts, washers, chassis. I'm telling you, magic has happened almost every time I've done that.

Thanks again, everybody!

Charles

 

Excellent Charles. Make sure you post some pics once you get that 12 SI alternator installed. 👍

 

Will do. Thanks!