possible sign of an alternator on its way out??

[tery]

I brought this one up a little while back and it is getting somewhat more pronounced. When the car first starts up every other or so time...the bat light is on, if I give it some gas it goes off and sometimes it comes on idling at a light, but again goes off with accel. The other thing is that when the engine...and/or alt is cold, I can see a definite pulsing in the interior lighting, like the dash and eatc etc. and even feel it in the idle, but it is definitely not a misfiring. Once the engine is fully warm, I see it very very little if t all and not at all when tooling along on the highway. Could it be that the alternator is on its way out and need to get the brushes etc hot...expanded a few microns to get better contact and put out the proper voltage??/ Just theorizing here. THoughts??

PS the battery is new and does get recharged near as I can tell....Never slow to crank but I've just been driving it a few days. It did sit for the past two months with periodic start up and one of two short trips to keep brakes moving etc...and battery held charge, even through some 20 below consecutive days and nights, But I saw the pulsing when I first got the car, it's just a bit more pronounced now until she's warmed up...

 

[rubydist]

it sounds like one of the rectifier diodes is bad, which both allowing some voltage fluxuation (pulsing) and reduces the output of the alternator. My experience is that the only rebuilt alternators that will actually last a decent time are the NAPA lifetime guarantee ones. I don't know if they are actually better than the other NAPA ones, or if I just had better luck with them, but they are the only ones I got that didn't die between the one year anniversary and the two year anniversary.

 

[tery]

Hey, thanks, will it leave me on the side of the road without an increasing set of symptoms, like just quit and then **** the battery or is it something that I would expect to just keep getting increasingly symptomatic??
When you have a sec,
T

 

[rubydist]

my experience is that by the time the alt light illuminates, the alternator is pretty weak, so I expect one morning you will attempt to start it and it will be dead. Once its running, the alternator should put out enough to keep it running, especially now that its daylight most of the time.

 

[Dirk37]

I'd recommend you get a new one soon, I got stranded (thankfully at the Auto shop where I work) when mine failed. It might last a long time or it might die the next time you take the car out, it's best not to take the chance.

 

[ISHOU]

Most definately an alternator as I had the same symptoms before the alternator finally died last week. As far as NAPA alternators go, the one that failed was a NAPA one with a 3 year warranty but NAPA said they would warranty it for life and the receipt stated such. It failed after 4 1/2 years and less than 30,000 miles. The 3 year alternator wasn't available locally but a lifetime one was so they gave me that instead. We'll see how it long it last. NAPA starters have not been good to me as two failed in three years.

On a different note, Tery you must eat, breath, and sleep SHOForum because you've posted 117 times in 3 months.

 

[SHOdded]

On a different note, Tery you must eat, breath, and sleep SHOForum because you've posted 117 times in 3 months.

With 3 SHOs to feed, he'd better!

 

[tery]

I just really appreciate the help the guys on this forum are willing to share. I put a post on a blazer forum and two months later, although many views, no one offers help. I've donated a couple times here cause this forum is terrific and terrific help to any and everyone who needs it. Rare to find these days it seems.

 

[go-to]

My car started this just today...time to have the alternator tested. :thank you:

Weird thing is the voltage checks fine at idle where the light comes on (about 13.7 volts). Rev it up, the light goes off and the DMM will shoot upwards of 16 volts. Now I know that's not a good sign.

Ok, now it won't charge passed 12.8 volts. :cry:

 

[tery]

Thanks, I do really want to hear how and what works for you.
I replaced my alt with a forum purchase, and the problem was fixed. Haven't seen the light for a month. Just yesterday I did see it go on and revving turned it off, but there was no pulsing with the engine idle. so we'll see if it gets bask to where it was or if it was just an errant light.
Take CARE,
T

 

[intimdatr]

My car started this just today...time to have the alternator tested. :thank you:

Weird thing is the voltage checks fine at idle where the light comes on (about 13.7 volts). Rev it up, the light goes off and the DMM will shoot upwards of 16 volts. Now I know that's not a good sign.

Ok, now it won't charge passed 12.8 volts. :cry:

The voltage regulator is dying, time for a new one. Sucks but thats how it goes. If you have a local shop that rebuilds them DO IT. Remans never last or work as well as they should.

 

[rubydist]

Thanks, I do really want to hear how and what works for you.
I replaced my alt with a forum purchase, and the problem was fixed. Haven't seen the light for a month. Just yesterday I did see it go on and revving turned it off, but there was no pulsing with the engine idle. so we'll see if it gets bask to where it was or if it was just an errant light.
Take CARE,
T

there are multiple ways these things die, and if just one of the rectifier diodes goes out, the vr can generally keep the flicker under control, but the power output will be reduced, especially noticeable at idle. I would guess that is what is wrong now.

 

[go-to]

The voltage regulator is dying, time for a new one. Sucks but that's how it goes. If you have a local shop that rebuilds them DO IT. Remans never last or work as well as they should.

Thanks, I found the regulator by itself for $144, but a new alternator from SHO Source is $170. That's a no-brainer for me.

There is an OLD shop in town that rebuilds anything based on an electrical motor and they are really really good at it...they can even rewind a motor or alternator.

I'm going to just order a new unit from SHO Source.

 

[DeepPower]

You might want to try disconnecting the battery, cleaning the battery terminals and cable connector, then tightly connecting again. It's a long shot, but it's a free fix if it works.

 

[go-to]

You might want to try disconnecting the battery, cleaning the battery terminals and cable connector, then tightly connecting again. It's a long shot, but it's a free fix if it works.

I just did that when all the gaskets and seals got changed.

 

[go-to]

Something new for me...

When I rev up to about 2500rpm, the EATC and sub amp shut down.

They do come back on though.

 

[tery]

I got new diodes in the mail today, I'm going to replace all three and see if when I put it back on the car, the pulsing issue is resolved. If it is..Whoo Hoo, Five dollar fix.
T

It worked!!. It tested good at the shop...Wow, won that one.

 

[pneps]

I was having issues with my '92 MTX. The CEL kept going on and off during driving and the car would run like crap when the CEL light was on. Then the Cel light would go off and the car would run fine. Pulled the codes several times and kept getting either no codes or differing codes. Replaced several sensors and a new DIS module and a new coil paack with no success. Finally found out it was the voltage regulator going bad.replaced the alternator 3 months ago, runs great and no CEL staring me in the face.

 

[go-to]

Replaced my alternator with a new unit from SHO Source (thank you very much!) and all is right with the world again.

Well maybe not...from sitting I found there is a leak in the A/C system and freon is low. Also, after a short drive the tach. went to zero and I got a check engine light. The car would not start after parking. I assume cam or crank sensor?!

Man, it never ends!

 

[mphowington]

CPS for sure...pull codes of course, but it will likely randomly start and then not. one of my least favorite jobs