M923 Alternator Magic Smoke got out...

[IsaLandr]

Taking Biff, our M923, out to the fueling station for a top-up, and the alternator stopped charging. I didn't see, hear, or smell anything, but it stopped charging. My best guess is that the Magic Smoke has escaped.

It was behaving somewhat erratically prior to this trip, to be honest. The needle on the gauge dropped into the mid-yellow for a few seconds, and then popped back into the green where it belongs. Did that three or four times yesterday, but then stayed in the green and was charging normally after that. I put my multimeter on it, and it was showing correct voltage.

Today on the trip to the fueling station, about 8 miles each way, the needle dropped into the yellow again for a few seconds twice along the way. Then, as I was pulling into the station, it dropped into the yellow and stayed there. I shut the truck down, fueled up, restarted, and... same. That's where it stayed for the whole trip back to the farm.

I put my multimeter on it when I got it back, and it's showing slightly low battery voltage at the slave port, and at the batteries themselves. The alternator appears to be putting out no voltage at all. It had been showing slightly low a year ago (25vdc), and using the search function here, I found the information to adjust the regulator up to 28.6vdc, where it's happily stayed from then to now.

I've got two of the four batteries currently on chargers, and will switch them to the other two when those batteries are done. Reading the various posts and searching a bit, it seems that trying to top up already low batteries puts too much strain on the alternator, which pops the regulator. That's probably what happened to mine, the batteries were a bit low. So that's the assumption I'm running on at the moment, although I'm also suspicious of the brushes. Please feel free to correct me if my reasoning is faulty.

I'll also add that this morning, when I first started it, the needle on the gauge was in the high yellow, and would only creep up into the green as I increased engine RPM. At idle, it would stay in the high yellow. Cruising down the road, it was where it's supposed to be in the green, but anytime the RPMs dropped, so would the needle. My guess is that this is indicating the regulator was on its way out? Maybe? Or maybe the brushes were not functioning properly?

Please don't tell me to RTFM, or to use the search function on this site. I've done both of those. What I'd like to get are suggestions or recommendations, preferences, for getting this fixed. Pros and cons for different methods, rather than telling me to go research it myself. I've done that, and there are conflicting opinions. Replace the whole alternator with a Delco civilian unit. Get the regulator rebuilt. Put on a new regulator. Replace the stock unit with another OEM unit. Have the whole alternator rebuilt. And so forth. I'm not sure what I want to do on this yet, so I'm looking for persuasive arguments in favour of one or another method.

Thoughts, suggestions, recommendations?

 

[Postman515]

Delco SI...

 

[machinist75]

Don't think about it anymore. Just order one of these kits from these guys, $255 and it bolts right on. Tell them your on steel soldiers and they may give you a discount, they gave me one and a spare rebuild kit for free.

 

[IsaLandr]

Don't think about it anymore. Just order one of these kits from these guys, $255 and it bolts right on. Tell them your on steel soldiers and they may give you a discount, they gave me one and a spare rebuild kit for free.

It would help if there were links or some other identifier in your post. Were there supposed to be links on "these kits" and "these guys"? Because from your post I don't know who those guys are or what kits you're talking about. Some clarification would be very useful here.

Also, thank you for the input. Is there a compelling argument in favour of your suggestion?

 

[swbradley1]

I guess I probably shouldn't you this but did you even bother to look at the bottom of this page with all the alternator threads?


But someone else searched for you.


http://www.wolverinetechnologiesllc.com/M925Alternator.html

 

[IsaLandr]

I guess I probably shouldn't you this but did you even bother to look at the bottom of this page with all the alternator threads?


But someone else searched for you.


http://www.wolverinetechnologiesllc.com/M925Alternator.html

Thank you for the link. Is that what the previous poster was referring to? There's no way to tell. Maybe these are two different solutions. Which one is better? That probably is the same one, I doubt there are two kits with the same price from two different vendors, but you never know. It still leaves the question, what makes this solution better than others?

I did see that one in my previous searching. As I mentioned up above in my initial post, I searched the forum, read the threads, and also looked through the TMs. In case you missed it, I'm looking for compelling arguments in favour of or against various solutions. There are lots of ideas, lots of ways to deal with this issue, but not a lot of supporting evidence of why people choose one way over another. I want to know what people have done, and why they think their solution was the best one. Just posting a link or saying do something specific, without supporting arguments, doesn't answer my questions or help me decide which solution to pursue.

It seems like a simple concept. If you have a preferred solution, I want to know what it is, and why you prefer it over the others. Pros and cons.

 

[74M35A2]

Depends on what your priorities are. More output than stock? Better reliability than stock? Lowest replacement cost? Easiest direct drop in replacement? Want new/used/rebuilt? Lighter weight? All can not be obtained simultaneously.

There are almost dozens to chose from, but before going down a wasteful path, state your desired intentions first.

From the way you described your failure mode, it sounds like one of the phases dropped out. The alternator is configured into 3 separate phases, each having their own set of diodes to convert or "rectify" the produced AC into DC. If these diodes fail (heat) in one phase, the alternator will lose 1/3 of its charging capacity. This then overloads the other 2 phases, and those quickly follow suit in failure also. This is why you had no charging at idle but some charging when rpm was up, but not much, and not for long. A real alternator should be able to charge discharged batteries without suicide. That is, after all, a portion of the alternator's primary job description.

 

[IsaLandr]

Depends on what your priorities are. More output than stock? Better reliability than stock? Lowest replacement cost? Easiest direct drop in replacement? Want new/used/rebuilt? Lighter weight? All can not be obtained simultaneously.

There are almost dozens to chose from, but before going down a wasteful path, state your desired intentions first.

From the way you described your failure mode, it sounds like one of the phases dropped out. The alternator is configured into 3 separate phases, each having their own set of diodes to convert or "rectify" the produced AC into DC. If these diodes fail (heat) in one phase, the alternator will lose 1/3 of its charging capacity. This then overloads the other 2 phases, and those quickly follow suit in failure also. This is why you had no charging at idle but some charging when rpm was up, but not much, and not for long. A real alternator should be able to charge discharged batteries without suicide. That is, after all, a portion of the alternator's primary job description.

Thank you, this is exactly what I mean. There are a lot of options, and I really don't know what the pluses and minuses to each one might be. I've been doing a lot of reading, but... The reality is, lots of guys have done lots of things, but mostly they don't really say why they chose what they did, or what the benefits or downsides to their choices were.

I'm not exactly sure what I want, which is why I wanted multiple options, with a good argument for or against each one. I usually tend to lean towards keeping everything stock, as intended by the original engineers... But at the same time, if I can increase reliability, that would be a plus, since I don't want to have to do this again anytime soon. I don't care if it's lighter weight, and the new/used/rebuilt part doesn't matter much to me as long as it works reliably.

I think the two most important criteria would be reliability and ease of replacement, followed by cost. I really would prefer something more robust than the original, but I don't want to have to alter the mountings to do it, if I can avoid doing so. On the other hand, there are some nice aftermarket kits that come with everything needed to do the swap painlessly. The link posted above is very tempting, though not the most economical solution. I do like the ease of its bolt-in nature, to be sure.

In terms of cost, I would prefer to keep the cost as low as is reasonably possible, but... with these trucks, that's not always in the cards. I agree, the alternator shouldn't drop out trying to recharge discharged batteries, but... there are an awful lot of stories right here on Steel Soldiers of the stock alternator doing just that. If I could get away with just replacing the regulator, at least temporarily, I might consider that, while I gather the resources to do one of the other options down the road a bit. But if it's seriously more economical, maybe it would be best to do one of the others right now and not have to worry about it later. Hence the request for comparisons.

 

[74M35A2]

So with that additional info, I would not recommend you repair your existing alternator (likely not the regulator in this particular case), or replace it with the same design which has a generally unacceptable failure rate. The cooling for these units is marginal at best, and when fully loaded, and held at idle, the electronics temperatures exceed their threshold.

The Wolverine solution is a good step forward that most take and have good success with. I believe he is using Chinese clones of Delco units for that price level, but if cloned well, their reliability should be about the same as the original, which is decent and a step above what you would be replacing. Some here have ran them for several years so far with no failure yet. I'd consider his price a steal consider the stock replacement is lower grade and about double his cost.

If you really had to drive the price lower than Wolverine, you could buy the same alternator for as low as $79 and gather the hardware yourself, which will take time and $. You may need a pulley, bolts, washers, spacers, etc. This is where he has done the homework already, and is only charging a small margin to make it turn key for you.

By combining your desire of low cost, minimal work, and bump in reliability, I'd suggest the Wolverine kit. His site says SS discount below his posted price. I have spoken with him on the phone, and he is a very polite person. He will likely honor the warranty better than a place which sells the same unit for $79 and has no posted phone number, if you have any issues with it.

There are other options of greatly increased output and reliability, but they start at the $450 price level and can exceed $1000, so I don't think they need further exploration in this case.

 

[machinist75]

That's what I was posting about. I was so excited about helping a brotha out I forgot to post the link. Wolverine tech is the way to go, they are members on steel soldiers.

http://wolverinetechnologiesllc.com/M925Alternator.html

 

[MtnSnow]

With what you have listed as your top 3 criteria I would wholeheartedly say do the conversion to the Delco SI alternator. Less expensive that the military unit, Much easier to get replacement if ever needed again as they are stocked in many parts houses and lastly they more reliable than the stock military unit.

 

[IsaLandr]

Thank you, gentlemen. That is exactly what I needed. Good arguments for a suitable solution. The Wolverine kit looks like my best option at this time. That's what I wanted to know.

Now to scrabble together the funds needed to buy the kit. Getting laid off last month has really put a crimp in my progress.

 

[IsaLandr]

Update: Okay, this is just odd. I went out and started Biff and let it run for a minute or so... the alternator started charging again. The needle on the gauge was down at the top of the red on the left side when I started cranking. Once the engine started, the needle had dropped a bit so there was some space between it and the line at the edge where red meets yellow. When I pushed down on the accelerator pedal, the needle moved closer to the yellow. The more fuel I gave it, the more the needle moved... Untill without warning, it jumped up into the high yellow, and then into the green.

Now at idle it's still in the high yellow, but at higher RPM it goes into the green. between 1000 and 1500 it hits the proper reading mark and pretty much sits there untill I drop it to idle again. Pushing up to 2100 doesn't cause an overcharge, either. I am confused. I thought the alternator was dead. What gives?

I'm still going to replace it, but... now I'm curious as to what's going on. It had stopped charging entirely, now it's charging again. What is this behaviour indicative of? Can anyone provide an insight into what it's doing and why?

 

[74M35A2]

Sounds like loose belt, loose connections and/or a dropped phase in the alternator as stated above. Proper procedure from here would be the following:

A. Insure all connections are clean and tight, do this not by simply looking at them. Loosen, clean, and reassemble firmly, all at battery and alternator ends.
B. Insure alternator is receiving proper 24V signal to energize (turn on).
C. Check and adjust belt condition and tension.
D. Check system voltage with a known good digital volt meter at various engine speeds including off and at various electrical loads, at both the battery and alternator ends. Any difference of more than 1V between the two indicates a bad connection or wire between the two.
E. Adjust system voltage via set screw on alternator (apply RTFM here).

Proper diagnostics with data collection is the correct way to tell what is wrong. Could armchair quarterback it, but wrong info can and typically produce(s) wrong result.

 

[doghead]

Are your belts tight, grounds clean and tight, an battery connections all clean and tight?

Have you load tested your batteries?

 

[Swamp Donkey]

Is the alternator belt tight and in good condition? Belts don't always make noise when they slip.

Do you have any other electrical issues other than charging, like ABS faults, etc.? Does the heater fan work on High? A bad PCB can cause charging issues, along with the other things I listed.

Edit: Apparently I'm a slow typer, lol.