Diesel alternator

[zuhandenheit]

I'm totally confused.

I think it's time for a new alternator. I'm not at all sure which I need. Busdepot lists six options:

http://www.busdepot.com/view.jsp?model=59&category=13&group=79&prodgroup=595

And I know they don't always do a good job of separating the diesel stuff from the gas stuff, so at least a few of these probably are wrong.

Gowesty doesn't appear to have a diesel alt.

Jcwhitney lists three: http://www.jcwhitney.com/BOSCH-HIGH-OUTPUT-ALTERNA...diaCode=ZX


I'd like to use a 90 amp if possible, but i'm not really attached to that.

[zuhandenheit]

ALSO, I think my problem could be the voltage regulator, could I replace just that?

Here, by the way, is what's happening: Voltage drops down below 12v, seemingly at random.

When I increase the current draw (lights or heater blower) usually the power drops below 12v, then sometimes back up to 12, occasionally higher (13-14), and then down again after awhile.

Sometimes it seems fine for while (over 13v) and then suddenly the power drops to under 12.

Belt is new and seems fine. Battery is new.

The alt light does not come on, so i guess the alt is always making *some* power. I've seen it come on before (when i had accidentally disconnected something) so i know that it works.

[Luckypabst]

What I've found is that there are only two alternators available for the early diesels - one is a Bosch and one is a Motorola. Both have a long offset pulley and the mounting ears are situated at 180 degrees from one another and are unique to the diesels (Rabbit and Van).

I was on the phone with my generator shop owning friend just yesterday in hopes that there's been any progress on the high amperage front. He said to scab on a GM or Ford alternator because there are no off the shelf options for upgrades.

For replacement - the generator shop friend always shrugs off my requests for him to rebuild my Motorola alternators, saying that certain parts are getting hard to find. He did pull off the shelf a new "hecho in Yugoslavia" Motorola knock-off for my Rabbit that he gave me for free. I had Napa trade me for one of their remans when the bearings gave up in my van alt. Both alternators seem to work fine with the Yugoslav alt acting a little weaker at idle, judging by the flickering pilot light.

So I guess what I'm trying to say is that there isn't much available for upgrades out there.

Chris
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'82 TD Westy
'81 NA Caddy

[?Waldo?]

You can fit the WBX 90 amp alt if you make a longer curved adjustment arm for the alt bracket.

Andrew
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I am a high-functioning autistic into VW diesels and Vanagons along with other things that are unrelated to this site.

[austinado16]

[?Waldo?]

I would also mention that you should actually be seeing better than 14v at the battery with accessories on and revved to 2,000 rpms or so. Often, there are enough voltage drops due to age/corrosion that the battery sees a whole lot less, leading to harder starting. There is an adjustable voltage regulator available for the bosch unit for the same price as the non-adjustable one which lets you dial in the output voltage. If purchasing a new regulator, I'd always choose the adjustable one.

Andrew
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I am a high-functioning autistic into VW diesels and Vanagons along with other things that are unrelated to this site.

[crazyvwvanman]

There are various choices. This is where I would shop for a stock replacement.

http://www.autohausaz.com/search/product.aspx?sid=...Alternator

The AL25X is the most common STOCK diesel vanagon alternator, Bosch version 65 amp.

Many times rebuilt alternators do not come with the pulley and fan. These parts can't be swapped from Bosch to Motorola so be careful. My advice is to avoid the Motorola though they work fine.

UPGRADE?
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You can use a very common Bosch 90 amp to replace the 65 amp stock one. The pulley and fan will move over from Bosch 65 to Bosch 90. The adjusting bracket will now be too short as will the belt. Use the same belt as the waterpump for both alt and waterpump with a 90 amp. The alternator wiring will need modification and UPGRADE for the additional amps. The best choice of the 90 amp alternators is the AL33X as it has the W lead for the diesel tach if you need it or want it in the future. AL27X is the same 90 amp but without the tach.

Mark

[zuhandenheit]

Thanks for the responses! I'd planned to wait to post again until I've had a chance to try austinado's suggestion to check the brushes, but I haven't yet.

A few points:

I have a four led voltmeter on my cigarette lighter splitter. This gives me some idea of the voltage. I've also put a multimeter on the little power plug (Euro cig. lighter plug) next to the steering column for more accurate readings.

I have not checked the power directly at the battery or the alternator. But the erratic variability definitely suggests to me that it has something to do with the voltage regulator. The connections seem fairly clean. Some time ago, I added an extra, big ground wire from the battery to the chassis.

I have not noticed that bumps or motion effects the problem at all. I've tried messing with the wires while the engine is running, which had no effect.

Also--this is not a completely new problem. I noticed some time ago that occasionally the power would drop to around 12v, seemingly for no reason at all, and then return to around 14.

It became much worse after I accidentally ran down my battery (i left an inverter on for a few days without running the van), and then worse yet during a recent long trip.

---

It's a westy and I have a stereo with a 200w amp, and I have a 300w inverter, which i often use to power my laptop. I'd like to add a second battery at some point, and my headlights are slightly upgraded. So the extra power of a 90amp alt might be useful for me.

---

I do plan to replace the 1.6 with a td, and so if I can get by for awhile with this alternator (per austin's suggestions), it would be nice to not buy a new one. Of course, I guess I could just transfer it over . . .



Thanks again for the helpful replies. I'll pull off my alternator and look at it tonight or tomorrow.

[zuhandenheit]

Ok, I pulled off the voltage regulator just now. Here's what I saw:

[austinado16]

First of all, the way your testing voltage isn't accurate. It's like those LED air/fuel ratio sensors.......as soon as someone installs one they start fixating on those LED's and complaining that their fuel/air mixture isn't right.

If you want to know what your alternator is really producing, check the back of the alternator, and check again at the battery. If you find there's a big voltage drop, replace the B+ wire from the alternator to the battery positive, with a larger diameter 4 gauge wire that you have made up at NAPA. Same advice goes for the battery and engine ground cables. Run 2 gauge cables and you'll notice faster cold cranking, faster cold starts, better charging, better glow plug action.

Regarding that voltage regulator, the brushes are getting low, but they are worn evenly, so that's good. As I suggested, clean the corrosion of the metal grounding contacts you see there on it , and the metal "tang" you see just inside the back of the alternator. Put it back together. But consider ordering a new regulator. (you have a bosch unit, by the way)
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4 little pistons hammering themselves silly
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1970 Austin America
1966 Mercedes 250SE Coupe (sunroof & 4 on the floor)
1981 Volkswagen Rabbit Diesel LX P/u
1986 Kawasaki Ninja 600R
1990 GMC 1/2ton 4x4 Suburban
1995 Audi A6 Quattro Avant

[hentairobsan]

A buddy of mine suggested just having the 65 amp rebuilt into a 90 amp since it is the same size interior. That way you just reuse your alternator housing and bypass the bracket problem altogether. same old alternator shell that fits but 90 amps of new juice