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1970 Cadillac Fleetwood Brougham, not charging at idle, new alternator/regulator

Started by Tonyv_73, December 30, 2020, 06:57:42 PM

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Tonyv_73

My 1970 fleetwood with 29k miles is not charging at idle, the engine and carb is all set to factory specs, and runs perfectly, but the alternator does not charge at idle.  It’s a brand new alternator, and we put a new regulator as well.  Does anyone know what the stock part numbers is for the original alternator? I’m looking to put an original “delcotron” alternator from 1970 back in the car but I can’t seem to find what would be the best for the car. 
1963 Series 62 Convertible
1965 Eldorado
1966 Calais Sedan
1970 Fleetwood Brougham
1970 Wildcat
1970 Coupe Deville
1973 Eldorado Convertible
1974 Coupe Deville
1976 Coupe Deville
1981 Eldorado Biarritz
1985 Eldorado Commemorative Edition
1991 Brougham
1993 Eldorado 4.9
1996 Fleetwood Brougham
2006 XLR
2006 DTS
2014 XTS

79 Eldorado

Tony,
It's been a long time since I've done it but it's not that difficult to rebuild most of the things which go bad in an alternator from the 70's. When I did it the only thing which was tricky was figuring out you needed a tooth pick to keep the brushes held in until the assembly was together. If yours is original to your car you may wish to consider it. I didn't change the bearings. I suspect there's someone on the site who likely knows how to check each part... or a google search away.

Are you sure it's not charging at all? It was with an internally regulated alternator but a friend showed me a trick for knowing if the alternator is charging. If it is you can feel a magnetic pull by placing a screw driver tip close to the front snout while it's running.

Scott

69Deville

1969 Cadillac Deville Convertible
1966 Cadillac Series 60 Fleetwood
1996 Cadillac Fleetwood Brougham-sold :(

The Tassie Devil(le)

Is it charging at normal speeds?

Is the Ignition Light illuminated on Start-up and run?

If the engine is idling too slow, that could be the cause of the poor performance, as it does take voltage to get an Alternator working, as against a Generator, which will charge from really low revs, and with no voltage.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Roger Zimmermann

Quote from: The Tassie Devil(le) on December 31, 2020, 01:06:04 AM

If the engine is idling too slow, that could be the cause of the poor performance, as it does take voltage to get an Alternator working, as against a Generator, which will charge from really low revs, and with no voltage.

Bruce, are you not a bit confuse here? 1970 car has an alternator, the generator, which does not charge at idle, was a thing of the past.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

The Tassie Devil(le)

Quote from: Roger Zimmermann on December 31, 2020, 03:33:18 AM
Bruce, are you not a bit confuse here? 1970 car has an alternator, the generator, which does not charge at idle, was a thing of the past.
No confusion at all.   I was just highlighting the difference between an Alternator and a Generator in the actual charging department.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

walt chomosh #23510

Tony,
  Do yourself a favor and pull the alternator and make a visit to your local shop that overhauls alternators/starters/etc. They will do a few simple tests in no time.....then, you'll know ex actually what the problem is. ....walt...tusla,ok

chrisntam

AutoZone also checks alternators, IIRC.  Assuming there are none of the "old school" shops in your neck of the woods.
1970 Deville Convertible 
Dallas, Texas

savemy67

Hello Anthony,

Was the charging system working properly before you installed the new alternator and regulator?  If not, and you suspected a bad alternator and or regulator (thus your replacement of the parts), you may want to look again at the wiring, grounds, and battery to see if any of these components is in need of maintenance.

Respectfully submitted,

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Tonyv_73

the engine was detailed (repainted factory colors and cleaned) and some parts were changed out to look nicer.  So my original alternator is long gone.  I would like to get a factory 1970 alternator in order to have a better looking engine bay, then perform tests with that.  The idle is perfect, and the GEN light does not come on while running (bulb does work) My concern is that this replacement alternator is too low of an amperage for a FWB
1963 Series 62 Convertible
1965 Eldorado
1966 Calais Sedan
1970 Fleetwood Brougham
1970 Wildcat
1970 Coupe Deville
1973 Eldorado Convertible
1974 Coupe Deville
1976 Coupe Deville
1981 Eldorado Biarritz
1985 Eldorado Commemorative Edition
1991 Brougham
1993 Eldorado 4.9
1996 Fleetwood Brougham
2006 XLR
2006 DTS
2014 XTS

bcroe

I have seen low alternator output caused by failure of some diodes
in the 6 diode main output rectifier.  It still had some output on the
still functional diodes. 

The solution at this location would be an upgrade to an internally
regulated alternator.  Much simpler to maintain.  Bruce Roe

79 Eldorado

Quote from: bcroe on January 05, 2021, 02:33:35 PM
I have seen low alternator output caused by failure of some diodes in the 6 diode main output rectifier.  It still had some output on the
still functional diodes....

  Bruce Roe
Bruce,
I had the same issue on a 1968; partial output due to a diode problem. In my case the dash light was barely lighting and coming and going as I recall but I had partial output.

Scott

O. Ramirez

All my dash lights are really dim would my alternator cause that too?

Glen

Quote from: O. Ramirez on January 09, 2021, 11:38:09 PM
All my dash lights are really dim would my alternator cause that too?

Try rotating the headlight switch knob.  I think the dash light dimmer was still on the headlight switch.  The knob should be rotated every now and then to clean the contacts. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

O. Ramirez

Glen

Yeah I do that and it dims even more maybe it’s supposed to be that dim I just wish it was brighter. Like I can hardly see the the lighting on it at night. It would be nice if it was a little brighter

Cape Cod Fleetwood

Quote from: O. Ramirez on January 10, 2021, 12:37:58 AM
Glen

Yeah I do that and it dims even more maybe it’s supposed to be that dim I just wish it was brighter. Like I can hardly see the the lighting on it at night. It would be nice if it was a little brighter

I have the same problem, old lights, old dash being looked at with old eyes I guess.
That headlight switch, that controls the brightness of the dash lights, is like $30, clean all the contacts with DeOxit.
I have a new switch in the "I'll get to it" pile. Directions for replacement are in your shop manual.
Still not bright enough? Change the dash lights to LED.
There are 2 kinds of cars in the world, Cadillac and everything else....

The Present -1970 Fleetwood Brougham

The Past -
1996 Deville Concours
1987 Sedan De Ville "Commonwealth Edition"
1981 Coupe De Ville (8-6-4)
1976 Sedan De Ville
1975 Sedan De Ville

The Daily Driver and work slave -
2008 GMC Acadia SLT *options/all

Roger Zimmermann

Quote from: O. Ramirez on January 09, 2021, 11:38:09 PM
All my dash lights are really dim would my alternator cause that too?
On my "new" '72 coupe, I had the same problem. It seems that the design is the culprit: I cleaned everything for the same result. Finally, I replaced all the bulbs with LED ones. I used the type 194-NWHP5 from Super Bright LEDs Inc. What a difference! They are even dimmable.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

79 Eldorado

My Cadillac is a 1979 but I had instrumentation lighting issues. I was fairly certain it was burned out bulbs so when I took the dash out to do the heater core I checked everything and replaced the burned out bulbs. It looks great now.

If there's a little bit of a soft/ slow / almost like slow rolling waves type change in intensity, without touching the switch, there is a possibility it's your charging system but if they're constant but not bright enough, regardless of switch rotation, it could be ground/ contact at the bulb or burned out bulbs. I also thought about LED's but I was concerned about areas being too bright and a potential for a dimming issue. Roger mentioned he found something which dims normally. If it also provides even lighting, without noticeable bright spots, then I would stick with exactly the version he found or I would use the original type.

Scott

Roger Zimmermann

Scott, there is no bright spot; the illumination is what I expected. I once bought halogen bulbs type 57. What an error! Especially on newer cars, those bulbs  radiate too much heat, fatal for plastic instrument clusters.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Tonyv_73

going back to the original discussion, someone recomended that I may have a bad connection somewhere,  When I originally got the car back from the shop, I went to put the headlights on and nothing happened.  Theres a harness that I touched on the firewall that immediately got the lights to turn on, He said it is possible theres still a bad connection so the car is not grounding properly, does anyone have a way to test this theory out?
1963 Series 62 Convertible
1965 Eldorado
1966 Calais Sedan
1970 Fleetwood Brougham
1970 Wildcat
1970 Coupe Deville
1973 Eldorado Convertible
1974 Coupe Deville
1976 Coupe Deville
1981 Eldorado Biarritz
1985 Eldorado Commemorative Edition
1991 Brougham
1993 Eldorado 4.9
1996 Fleetwood Brougham
2006 XLR
2006 DTS
2014 XTS