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telford dorr
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Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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 Posted: Wed Oct 20, 2010 9:53 pm Post subject: |
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| ... took my bus to the beach for about a 45 minute run and the generator (red ) light comes on at idle , goes out after rpms go up ,at idle 12.1 at battery and goes to 12.8 at high rpm , went and got a new regulator and put it in and its doing the same thing |
You gotta do the test outlined in the Bentley: run the generator without the regulator and jumper DF to ground. See the test writeup for details. If this test passes, the generator is good, and the problem lies elsewhere. The test is absolute - will either verify or disqualify the generator.
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'71 panel, now with FI
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More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Wed Oct 20, 2010 10:53 pm Post subject: |
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| 68nofussbus wrote: |
| Back again , Havnt had any time to do much with the bus since i put in generator , took my bus to the beach for about a 45 minute run and the generator (red ) light comes on at idle , goes out after rpms go up ,at idle 12.1 at battery and goes to 12.8 at high rpm , went and got a new regulater and put it in and its doing the same thing .... did i fry my new generator already ? took old regulator apart and smells burnt .. the new regulator says to polorize it so I did what it says and still the same low voltage at idle and 12.8 at high rpm , do i have to polorize the generator too ...... trying to diagnose before pulling the generator again and replacing ..... I hope im forgetting to do something so I dont have to pull and reinstall a new generator .. thanks |
so if we drove it with the old regulator we may have fried the generator. Follow the procedure in Bentley to test it. Now is a good time to read that chapter.
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68nofussbus
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Joined: March 28, 2007
Posts: 334
Location: Hot & Humid Florida
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| Posted: Thu Oct 21, 2010 8:33 am Post subject: |
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| Yep the bentley chap confirmed the generator is shot , lesson learned ! Put new/reman. Bosch in and it works perfect . $31 regulator cost me 2 hours of my time and $3 in tolls to auto parts store ,if I just would of changed the regulator at the same time ,atleast they took the generator back and replaced it , I got lucky !!!!!!! |
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60vwnewengland
Twin #2
Joined: June 25, 2003
Posts: 1784
Location: District of Columbia & Cape Cod
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| Posted: Tue Aug 16, 2011 7:34 am Post subject: |
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my generator doesn't say what AMPS it is.
All that's on it is a sticker, GR15N. It's a rebuilt generator from advanced...
how amps is that one?
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77 Westy - Cape Cod Sage
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busdaddy
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Joined: February 12, 2004
Posts: 51125
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Aug 16, 2011 7:40 am Post subject: |
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GR15=30A
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60vwnewengland
Twin #2
Joined: June 25, 2003
Posts: 1784
Location: District of Columbia & Cape Cod
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| Posted: Tue Aug 16, 2011 7:43 am Post subject: |
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Thanks BD I've been searching for this answer for days
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VAVWFAN
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Joined: January 16, 2010
Posts: 758
Location: Middletown, Virginia
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| Posted: Tue Aug 16, 2011 8:11 am Post subject: |
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The regulator I got from Advance Auto required for my 69 Westy "polarization" prior to use. I read the instructions that came with the VR, and all has been well for 2.5 years now.
It wasn't a Bosch VR, but appeared to be older knock-off. Regardless, it works fine, and I'm good with that!
Not sure if your version of the VR required polarizing, but just wanted to pass my experience on...........
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60vwnewengland
Twin #2
Joined: June 25, 2003
Posts: 1784
Location: District of Columbia & Cape Cod
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| Posted: Tue Aug 16, 2011 8:16 am Post subject: |
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| VAVWFAN wrote: |
The regulator I got from Advance Auto required for my 69 Westy "polarization" prior to use. I read the instructions that came with the VR, and all has been well for 2.5 years now.
It wasn't a Bosch VR, but appeared to be older knock-off. Regardless, it works fine, and I'm good with that!
Not sure if your version of the VR required polarizing, but just wanted to pass my experience on........... |
I got that one as well. I did not polarize it. I think those instrustions are in there if you did not polarize the generator.
This weekend I was going down the highway at 65mph, look down and the gen light comes on. Pull over, belt not thrown, connections are good, hit the generator with a hammer a few times, nothing, light still on. I drove the bus 15miles to my brother's place, left it there till I could get a new regulator.
That gen and regulator only have 5k on them. Rebuilt Bosch generator (GR15N), and the regulator you are talking about. It's weird for it to burn out after 5k. But I will replace it, see what happens. I just got the generator light working too, so it might be a lose connection behind the cluster?
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Tcash
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Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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| Posted: Fri Jul 31, 2015 1:54 pm Post subject: 30A-38A generator length |
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| Joey wrote: |
As long as the 38A generator has the correct backing plate and the 30A generator as the correct backing plate you can swap them all day long. The reason for the different backing plate is the 38A generator is longer...
Using a 30A regulator with a 38A generator means you will only get 30A output. |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
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| Posted: Fri Jul 31, 2015 2:05 pm Post subject: Re: 30A-38A generator length |
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| Joey wrote: |
As long as the 38A generator has the correct backing plate and the 30A generator as the correct backing plate you can swap them all day long. The reason for the different backing plate is the 38A generator is longer...
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The 38a generator also has a cast iron pulley that, according to my understanding, helps the 38a generator align the belt with the crank pulley.
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GeorgeL
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| Posted: Fri Jul 31, 2015 4:47 pm Post subject: |
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| I ran a 38A for a long time with a standard stamped pulley. The alignment seemed to be fine. The cast pulleys are pretty darned rare. |
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airschooled
Air-Schooled
Joined: April 04, 2012
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Location: on a bike ride somewhere
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| Posted: Fri Jul 31, 2015 6:38 pm Post subject: |
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| GeorgeL wrote: |
| The cast pulleys are pretty darned rare. |
That's the truth. The week I learned about them, I found a NOS one for $30 and just about spat out my coffee. 
Seeing how the fan shroud fits in the tins which have a bit of play on the heads which may not be a VW casting which may be too far out due to stroke which may need aftermarket cylinder tin which may not index the fan shroud correctly, I said the pulley "helps."
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Last edited by airschooled on Fri Jul 31, 2015 7:07 pm; edited 1 time in total |
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SGKent
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Fri Jul 31, 2015 6:53 pm Post subject: |
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Every once in awhile I consider finding a 1971 bus again and using a 38 amp generator in it. This is what I thought most looked like based on the original 1971 I had. What do the different pulleys looks like?
http://www.thesamba.com/vw/classifieds/detail.php?id=1652879
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airschooled
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Location: on a bike ride somewhere
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| Posted: Fri Jul 31, 2015 7:07 pm Post subject: |
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Different whats?
That's a 38a generator on a 30a backing plate. The "dish" an inch or two around the gen on the correct backing plate (below) helps compensate for the extra length. The pulley pictured in the ad is the correct cast iron pulley, judging by the tiny clearance between it and the gen housing. (Technically, only the front front pulley half is cast iron.)
The tricky part about the pulleys, is the gorilla-fisted mechanics who mangle the locking cutout when meshing the screwdriver between the gen and pulley to tighten the belt. Used ones are usually no bueno for this reason.
Robbie
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SGKent
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| Posted: Fri Jul 31, 2015 7:45 pm Post subject: |
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pulley's. Cast vs stamped. I would think used OGVW pulleys would be plentiful.
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airschooled
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| Posted: Fri Jul 31, 2015 7:48 pm Post subject: |
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| SGKent wrote: |
| pulley's. Cast vs stamped. I would think used OGVW pulleys would be plentiful. |
They might be. It's just getting hard to find someone who cares enough to know, spot, and acknowledge the difference when they're selling someone as common as a pulley... I found two in four months of looking, and they certainly can't be bought new.
Here is a shot of one I found online. I think those are factory balance holes.
"But the chrome ones are cheaper, dood!"
Robbie
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GeorgeL
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| Posted: Fri Jul 31, 2015 8:09 pm Post subject: |
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The other item that is different is the fan hub forward of the backing plate the dished tin positions the generator shaft further forward so a different hub is needed to move the fan backwards for proper clearance with the backing plate.
Personally, I got tired of chasing generator and regulator problems and switched to an alternator. There was a reason that VW eventually switched over to them! |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
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| Posted: Fri Jul 31, 2015 8:17 pm Post subject: |
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| GeorgeL wrote: |
The other item that is different is the fan hub forward of the backing plate the dished tin positions the generator shaft further forward so a different hub is needed to move the fan backwards for proper clearance with the backing plate.
Personally, I got tired of chasing generator and regulator problems and switched to an alternator. There was a reason that VW eventually switched over to them! |
Yes, different hub. Shown here on the right center. On the left is a 30a/alt fan hub for a doghouse fan.
I have never had an issue with either system, so given the choice for now, I will take being able to push start with the completely dead battery any day over something more technologically advanced. Full disclosure, my electrical system from the starter back is entirely NOS, so there's that!
Robbie
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Fri Jul 31, 2015 8:21 pm Post subject: |
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I think that's a stamped pulley in the ad, the cast (possibly even forged, but they break around the screwdriver slots easily) ones are much thinner on the generator side, by 1/8" +. The stamped ones work OK but the belt is still a tiny bit off.
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airschooled
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| Posted: Fri Jul 31, 2015 8:37 pm Post subject: |
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So is it not the thin one on the right? ( These pics are from different ads I've saved over the years)
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