Alternator light on - but Voltage fine?

[HastaAlaska]

Hey Guys, here's an update, it's still not good..

WHAT HAPPENED

I received a new pulley, poor quality vs the CB Performance one I had, but the only one available.

I installed it with approximately 10-12mm of play in the belt (Bently specifies approximately 10mm I believe) - Checked it after a short run and the play was still about 10-12mm. There are 2 shims inside the pulley and 8 outside. (all proper-sized shims now I believe.)

I drove across Siciliy yesterday ( 5 hours of driving) and when I arrived at Palermo on the other side the belt was tighter, probably 7mm of play.

The alternator was stinking up the cab again with acrid fumes, there was some light belt dust on the pulley.

WHAT I'VE DONE/TRIED

* I tried clamping the nut down with and without the belt, the nut has the same number of turns for both scenarios, so I don't think it is clamping on the belt.

* I did an eyesight test of the angle of the belt, it looks in line with the crank pulley to me.


* I used a digital level to test the angle on both the crank pulley and the alt pulley. There is a 1.5 degree difference in the angle between the two pulleys

* Since arriving, I have changed the fan belt for a new one (same size, 900mm) - this did not help + removed the heat exchanger hoses so the fumes can't pump into the cab.

I'm totally baffled by this, it should be fairly straightforward. Is the angle an issue? has anyone heard of this issue before?

Thanks in advance for your replies.
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Around The World in a VW - Follow the Docuseries
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[bsairhead]

!.5 degrees is so close to spot on I can't believe that's the issue. The smell to me "sounds" like since I can't "smell" it overcharging of the battery. A voltage check would show that. Good luck in your travels.

[HastaAlaska]

[HastaAlaska]

Unfortunately, this alternator replacement only lasted 5000 miles before the exact same problem occurred. Red light on, 14v at B+, 17+v on D+

There was some excellent advice in this thread when I broke down in Italy, but despite taking everything apart and checking the orientation of the backing plate when I initially installed it ( i had indeed installed it upside down). The alternator continued to run very HOT, and despite being a 75A model, it was never able to output more than 20A without overheating, stinking up the cab.

My theory is that it wasn't properly grounded. The original Bosch 55A model that lasted much longer (under heavier loads) never had a dedicated ground; it grounded via the alternator stand and the metal retaining clamp. However, perhaps the new 75A model wasn't able to ground in the same way as the original Bosch one, and perhaps it needed a dedicated ground cable? This could explain the excessive heat and premature life.


Anyway, new alternator inbound. If there is anything else that could cause an alt to overheat, I'd be happy to hear your theories.

Cheers

Ben
(Now in Greece)
_________________
Around The World in a VW - Follow the Docuseries
2011 - 20Something
Latest Adventure Series - https://bit.ly/LifeDoneDifferently

[mikewire]

Honestly Ben, going back and reading through your previous posts (it's been a minute) it sounds like you got a bunk 75A alternator with problems from the get-go. Especially if it only lasted 5k miles, was constantly running hot, and only output 20A??? That's a bad part, bad QA, or someone incorrectly sold an unknown failed part in a new box (another customers return or RMA part?) if you ask me.

Let's hope the new alt is brand spanking new and glorious, and that it fixes your problems for miles to come. Inspect it well before installation.

Not a finger point or anything, but I am curious, (maybe I missed a previous post) where did you source this problematic alternator? And where are you sourcing the new one?
_________________
-Mike

@countdowngarage
@bigskyeuro

1972 VW Kombi 9 Passenger Deluxe 221(5) w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue

[SGKent]

sounds like maybe a shorted loop in the winding, resistance to ground, or bad diode passing AC. Since all these alternators are either made of chinesium or rebuilt cores of unknown history, it pays to put an oscilloscope on the output to see if the signal has any AC ripple or weirdness to it.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[richparker]

Get the pulley with the cooling fins, Brah…

https://www.cbperformance.com/product-p/2163.htm
_________________
__________
’71 Westy build
Adventure thread
’65 Deluxe Build
’71 Double Cab

[SGKent]

here is the output on one I rebuilt and Telford tested both it and the regulator(s) for me on his alternator test rig. Don't know what I would do without his help.

_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[TomWesty]

I think Telford is the only one of us that has a test rig for alternators.
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If you haven't bled on them, you haven't worked on them.
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[airschooled]

[HastaAlaska]

This time we were broken down for about 2 1/2 weeks resolving this issue, all just waiting for the part. We were able to drive a bit on the old alternator, probably 75 miles in total, whilst we waited, but the faulty alt started to be quite loud by the end.

I've now received and installed a new alternator, and I'm happy to say it is running much cooler and so far much happier. I have only run short journeys so far.

I've installed a dedicated ground this time. Perhaps that was the issue, or perhaps the casing wasn't very conductive, or perhaps there was too much dirt under the alternator stand strap contact point that I hadn't seen. Either way, I do hope that this is the last time for a long time.

The original alternator (75A) came from an Italian aircooled retailer; they seemed nice enough and I have no reason to doubt them. The new replacement (90A ) ) came from Jay at aircooledshop.com. He actually sent me a free spare 75A alternator because he didn't have the one I ordered in the right color. wow. Hopefully I won't need it.

[Abscate]

[HastaAlaska]

[SGKent]

Your pulley shows evidence of not being properly tightened, and also belt hop.

A spacer behind the pulley, and shims between halves and under the nut hold play between halves to zero, and set where the belt runs. If there are not enough shims in both places then the pulley will rock and that will cause it to fatigue and fail like yours. It will also cause the wear pattern one sees on your pulley.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[Wildthings]