Is my alternator "FRIED"?
Thread Starter
Racer
Joined: Mar 1999
Posts: 323
Likes: 0
From: Webster, NY
Is my alternator "FRIED"?
Just today I was cruising around the neighborhood in my '90 when the engine seemed to lose power and the digital dash went out and then kept flickering. Just made it home and when I turned it off, it wouldn't restart. New battery just put in a week ago. The "info center" shows the battery lite on and the charge rate is down to nil when i got home. I'm thinking it's the alternator since it's NOT putting juice back into the battery. IS there any other explanation that could cause this problem? Wondering........this is got me really bummed. 
Burning Brakes
Joined: Apr 2005
Posts: 950
Likes: 0
From: Medicine Hat Alberta
Here's an old easy trick to see if the alternator is charging...Place a wrench behind the alternator on the nub that sticks out and while the engine is running carefully place the wrench on the nub in behind and if you feel a "MAGNETIC" attraction where the wrench sticks to the nub..this means it is charging...If it doesn't "ATTRACT" then she's done..time for a new one. But from what you are saying....I will bet my 96 coupe that your alternator is fried....It's an easy minor fix....nothing to be bummed out about...just part of general maintenance.
Last edited by HOOBS; Jul 24, 2005 at 12:53 AM. Reason: more info
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
First, charge up your battery with a battery charger. Alternators should not be expected to charge a dead battery, you will just fry another alternator. Next, start the engine, if the battery symbol light is on, the alternator is not charging the battery and the dash voltmeter will also tell that by indicating in the 12's. Normally the dash voltmeter will read close to 14.3 volts cold, 13.3 volts hot. Next, measure the battery terminal volts and compare that voltage with the alternator output terminal voltage. They should be the same if the alternator and its fusible link are ok. If the alternator reads 14 volts or so, but the battery reads under 13 volts, you have a blown fusible link in the alternator output wire and it needs to be replaced. You can also remove the alternator and take it a car parts place that will test it for free.
Burning Brakes
Joined: Oct 1999
Posts: 836
Likes: 0
From: Colorado Springs, Colo., USA
THIS IS AN ENDORSEMENT, BASED ON MY EXPERIENCE AS A c4 OWNER! (I now have a C5.) But I was spinning through alternators every two years with my C4. Chris Petris at Corvette Clinic in Sanford, Florida, produced an updated alternator for C4s. It was an alternator intended for use in heavy-duty applications like emergency response vehicles, adapted to the C4. I bought one and never replaced another alternator. The youngster who now owns my C4 has had no problems,either. That is six years with no alternator problems!
The alternator was the weak point on the C4, especially because most of us drive the cars infrequently, which places strain on the charging syste, unless you keep a charger on it that keeps the battery at a constant level.
I have no connection to Chris or the Corvette Clinic.
The alternator was the weak point on the C4, especially because most of us drive the cars infrequently, which places strain on the charging syste, unless you keep a charger on it that keeps the battery at a constant level.
I have no connection to Chris or the Corvette Clinic.
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Originally Posted by jfb
First, charge up your battery with a battery charger. Alternators should not be expected to charge a dead battery, you will just fry another alternator. Next, start the engine, if the battery symbol light is on, the alternator is not charging the battery and the dash voltmeter will also tell that by indicating in the 12's. Normally the dash voltmeter will read close to 14.3 volts cold, 13.3 volts hot. Next, measure the battery terminal volts and compare that voltage with the alternator output terminal voltage. They should be the same if the alternator and its fusible link are ok. If the alternator reads 14 volts or so, but the battery reads under 13 volts, you have a blown fusible link in the alternator output wire and it needs to be replaced. You can also remove the alternator and take it a car parts place that will test it for free.
Thread Starter
Racer
Joined: Mar 1999
Posts: 323
Likes: 0
From: Webster, NY
Fusible link?
Hey jfb, thanks for the reply, I have one question about something you mentioned....mainly the "fusible link"....where exactly is this link, how do you know if it's gone bad, and how is it replaced? One other question is concerning the serpentine belt...when I release the tension via the pulley, will my belt come completely off the rest of the pulleys?..will I have to re-route the belt all over again or can it be simply removed without disturbing the rest of the system? Thanks........
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Michael S. Palmer
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The fusible link is a part of the output wire from the alternator to the battery. It is a crimped in place piece of wire with heat shrinkable tubing over it. You can test the fusible link with an ohmeter by measuring between the battery positive terminal and the alternator output terminal. You should measure the same resistance as indicated when you touch your test probes together. If the link is open circuit and you didn't disconnect the negative battery cable, your ohmeter could show a funny reading because there will be 12 volts between the battery terminal and the alternator terminal. Its safest to disconnect the neg batt terminal, or use a flashlight battery and a 1.5 volt bulb to test continuity, or connect a 12v lamp from alternator output terminal to ground, it should light up.
Pro
Joined: May 2005
Posts: 635
Likes: 0
From: Cambria CA
As I've said before, I'm not an expert but I've had some experiences with my vette. First I fried the alternator, and the speedometer didnt blank out. I tried to start it again but it just started up then died after a while. So if it makes a sound while you start it up I'm not sure what it is. I recently was driving on the highway and my speedometer went out along with my stereo, which didn't retract into its off position. The car was running fine but I couldn't read the MPH so I pulled over. turned it off to try to start it back up but it wouldn't do anything, it wouldn't make any ignition sound at all. If this is the case then it could be a fuse. I think it was my brake fuse that went out and it must be some kind of safety feature for the car to not work while the brake fuse is blown. This is my .02, I dont know much but... Good Luck!
Last edited by Shawn_65; Jul 29, 2005 at 05:22 AM.
Pro
Joined: May 2005
Posts: 635
Likes: 0
From: Cambria CA
Originally Posted by Jim Nichols
This is my first hand experience. Before you replace the alternator, make sure that your battery lugs are making good contact. Three bucks for new lugs could have saved me about $250.
Jim
Jim
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
Go to AutoZone. They will test it for free.
If it is toast you can buy a remanufactured one with a 1 year guarantee for $69. It is an easy change..
Or as I did, when they told me the diodes were bad... take it apart and change the parts your self.\The diodes cost me $6
If it is toast you can buy a remanufactured one with a 1 year guarantee for $69. It is an easy change..
Or as I did, when they told me the diodes were bad... take it apart and change the parts your self.\The diodes cost me $6
Thread Starter
Racer
Joined: Mar 1999
Posts: 323
Likes: 0
From: Webster, NY
Is my alternator fried?
Hi rws. thanks for the suggestion, I did already check with AutoZone about their rebuilts but I'm thinking that maybe I'd be better off just having mine fixed (10K mile car). You mentioned changing the Diodes yourself, can you tell me what was involved and if it's necessary to solder anything? Is it very involved once you pull the case open? wondering what the procedure would involve to do it myself too. Thanks to all for their input. 
Heel & Toe
Joined: Jun 2003
Posts: 20
Likes: 0
From: Gainesville Fl
Here's a link to a site that explains everything. http://www.alternatorparts.com/cs130_sbpage1.htm
They have some hi-quality upgrade parts for these alternators.
They have some hi-quality upgrade parts for these alternators.
Thread Starter
Racer
Joined: Mar 1999
Posts: 323
Likes: 0
From: Webster, NY
Is my alternator fried?
Well, Vette is up and running well again. Problem turned out to be a "gone" rectifier. The shop rebuilding my alternator showed me the bad part and said it was a bad design and now replaced with a new and immproved rectifier with pressed in diodes. I got one of those belt tensioner tools from AutoZone and it didn't even fit into that tight space in a good positon to get some twist on the tensioner...so I ended up using a 1/2'' drive breaker bar with an "L" shaped tire iron on the end and it worked like a charm with the right angle and good leverage. Power steering resorvoir had to be undone so the bottom bolt of the alternator can be pulled out...wow, they sure make those compasrtments tight for any breathing room. I didn't want to get a rebuilt alternator and lose my original alternator so for $54 i got my original one back and I know it isn't all worn out being it comes from a 10K mile car. Thanks guys for all the input...............
