Re(2): Jeep alternator

On Tue, 1 Mar 2005, Smitty wrote:

> I took my 96 grand Cherokee in for a water pump replacement. The shop
> said that I also had a bad alternator. It worked fine in our -20 temps
> here in MN and the warning light has never come on. Do you think it
> could be bad?

Let me share a story which will help illuminate the matter:

At one time, I drove a very used 1991 ex-police Chev Caprice. One very
cold winter morning, I noticed a new noise from under the hood. Faint, but
present. Sort of an intermittent hissing/clicking sound coming from the
front. I carefully homed in on the alternator as the source of the noise
and made a mental note to replace it, for obviously one or both of its
bearings had begun to fail.

But life being what it is, I didn't get around to it. Working on cars is
very little fun in the winter, and the alternator was continuing to
charge. I fed a few drops of oil into the front bearing via the shaft and
kept on driving, periodically reminding myself that I ought to look at
changing the alternator. Eventually I pretty much forgot about it.

About 2 months later, I was on the highway doing about 65mph when a sudden
loud noise began to emanate from up front. It sounded like the moan of a
dead power steering pump, but it obviously wasn't, for I still had
steering boost. The noise rapidly grew louder and evolved into a
hair-raising grinding noise. The voltmeter dropped, the "AMP" light came
on, and the smell of very hot metal filled the car. The alternator's front
bearing had locked up solid, and the entire bearing was now spinning in
its interference fit, meant to keep the bearing's outer ring stationary in
the alternator's front housing.

It was still about 3 miles to the next exit. I decided to go for broke,
and kept on driving. The grinding sound got ever louder, the stink of
broiling metal grew heavier and hotter. I pulled off the highway at the
first opportunity, and found...nothing. No service station, no phone
booth, just an intersection.

Back on the highway, another mile down the road, I pulled off at the next
exit, into a gas station's parking area and killed the engine. I yanked
the hood release, lifted the hood, and a thick column of smoke poured up
from the *extremely* hot alternator. The once-greasy painted brackets were
now bare steel, dark pink in color. I ran into the convenience store,
bought a bottle of water, sprinted back outside and carefully poured it
over the alternator. The water instantly and loudly flashed into steam. I
bought another bottle of water, and another. By the time I had poured the
third litre of water over the alternator, it was merely fizzing rather
than flashing the water directly into steam.

There was a parts store with a service department one block down the road,
so I got back in the car and started the engine. The water treatment had
averted fire danger due to extreme heat, but in the time it had taken me
to buy the first bottle of water, the alternator had welded itself solid.
The 3-month-old serpentine belt skidded over the locked-up alternator
pulley and cooked itself to death in a big cloud of noxious smoke
during the one-block drive to the service center.

Three hours and $250 later, the car had a replacement alternator and a new
belt, both of unknown quality.

If this is your idea of a fun diversion during an important trip on an
unpredictable day, by all means ignore your mechanic.

If it isn't, ask him to be more specific about what's gone bad in the
alternator. I'm betting he gave the alternator a spin when he removed the
belt to replace the water pump, and felt a rough bearing.

DS

Daniel J. Stern wrote:
> On Tue, 1 Mar 2005, Smitty wrote:
>
>
>>I took my 96 grand Cherokee in for a water pump replacement. The shop
>>said that I also had a bad alternator. It worked fine in our -20 temps
>>here in MN and the warning light has never come on. Do you think it
>>could be bad?
>
>
> Let me share a story which will help illuminate the matter:
>
> At one time, I drove a very used 1991 ex-police Chev Caprice. One very
> cold winter morning, I noticed a new noise from under the hood. Faint, but
> present. Sort of an intermittent hissing/clicking sound coming from the
> front. I carefully homed in on the alternator as the source of the noise
> and made a mental note to replace it, for obviously one or both of its
> bearings had begun to fail.
>
> But life being what it is, I didn't get around to it. Working on cars is
> very little fun in the winter, and the alternator was continuing to
> charge. I fed a few drops of oil into the front bearing via the shaft and
> kept on driving, periodically reminding myself that I ought to look at
> changing the alternator. Eventually I pretty much forgot about it.
>
> About 2 months later, I was on the highway doing about 65mph when a sudden
> loud noise began to emanate from up front. It sounded like the moan of a
> dead power steering pump, but it obviously wasn't, for I still had
> steering boost. The noise rapidly grew louder and evolved into a
> hair-raising grinding noise. The voltmeter dropped, the "AMP" light came
> on, and the smell of very hot metal filled the car. The alternator's front
> bearing had locked up solid, and the entire bearing was now spinning in
> its interference fit, meant to keep the bearing's outer ring stationary in
> the alternator's front housing.
>
> It was still about 3 miles to the next exit. I decided to go for broke,
> and kept on driving. The grinding sound got ever louder, the stink of
> broiling metal grew heavier and hotter. I pulled off the highway at the
> first opportunity, and found...nothing. No service station, no phone
> booth, just an intersection.
>
> Back on the highway, another mile down the road, I pulled off at the next
> exit, into a gas station's parking area and killed the engine. I yanked
> the hood release, lifted the hood, and a thick column of smoke poured up
> from the *extremely* hot alternator. The once-greasy painted brackets were
> now bare steel, dark pink in color. I ran into the convenience store,
> bought a bottle of water, sprinted back outside and carefully poured it
> over the alternator. The water instantly and loudly flashed into steam. I
> bought another bottle of water, and another. By the time I had poured the
> third litre of water over the alternator, it was merely fizzing rather
> than flashing the water directly into steam.
>
> There was a parts store with a service department one block down the road,
> so I got back in the car and started the engine. The water treatment had
> averted fire danger due to extreme heat, but in the time it had taken me
> to buy the first bottle of water, the alternator had welded itself solid.
> The 3-month-old serpentine belt skidded over the locked-up alternator
> pulley and cooked itself to death in a big cloud of noxious smoke
> during the one-block drive to the service center.
>
> Three hours and $250 later, the car had a replacement alternator and a new
> belt, both of unknown quality.
>
> If this is your idea of a fun diversion during an important trip on an
> unpredictable day, by all means ignore your mechanic.
>
> If it isn't, ask him to be more specific about what's gone bad in the
> alternator. I'm betting he gave the alternator a spin when he removed the
> belt to replace the water pump, and felt a rough bearing.
>
> DS

Smitty posted a little earlier that both old and new alternators load
tested at 11V - so it sounds like something else is going on external to
the alternator.

Anyway - while we're telling war stories, I had a similar alternator
lock up on an '88 DeVille - my wife was driving by herself at the time.
She had to walk 1/4 mile to get me. So we drive back to it in my
car. The dust being thrown from the serpentine belt downstream of the
alt. pulley piled into a handy little crevice on top of the engine.
When I opened the hood, the pile of rubber dust was glowing red, just
like embers in a fireplace. Really weird and amazing.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

"Daniel J. Stern" > wrote in message
...
> On Tue, 1 Mar 2005, Smitty wrote:
>
> > I took my 96 grand Cherokee in for a water pump replacement. The shop
> > said that I also had a bad alternator. It worked fine in our -20 temps
> > here in MN and the warning light has never come on. Do you think it
> > could be bad?
>
> Let me share a story which will help illuminate the matter:
>
> At one time, I drove a very used 1991 ex-police Chev Caprice. One very
> cold winter morning, I noticed a new noise from under the hood. Faint, but
> present. Sort of an intermittent hissing/clicking sound coming from the
> front. I carefully homed in on the alternator as the source of the noise
> and made a mental note to replace it, for obviously one or both of its
> bearings had begun to fail.
>
> But life being what it is, I didn't get around to it. Working on cars is
> very little fun in the winter, and the alternator was continuing to
> charge. I fed a few drops of oil into the front bearing via the shaft and
> kept on driving, periodically reminding myself that I ought to look at
> changing the alternator. Eventually I pretty much forgot about it.
>
> About 2 months later, I was on the highway doing about 65mph when a sudden
> loud noise began to emanate from up front. It sounded like the moan of a
> dead power steering pump, but it obviously wasn't, for I still had
> steering boost. The noise rapidly grew louder and evolved into a
> hair-raising grinding noise. The voltmeter dropped, the "AMP" light came
> on, and the smell of very hot metal filled the car. The alternator's front
> bearing had locked up solid, and the entire bearing was now spinning in
> its interference fit, meant to keep the bearing's outer ring stationary in
> the alternator's front housing.
>
> It was still about 3 miles to the next exit. I decided to go for broke,
> and kept on driving. The grinding sound got ever louder, the stink of
> broiling metal grew heavier and hotter. I pulled off the highway at the
> first opportunity, and found...nothing. No service station, no phone
> booth, just an intersection.
>
> Back on the highway, another mile down the road, I pulled off at the next
> exit, into a gas station's parking area and killed the engine. I yanked
> the hood release, lifted the hood, and a thick column of smoke poured up
> from the *extremely* hot alternator. The once-greasy painted brackets were
> now bare steel, dark pink in color. I ran into the convenience store,
> bought a bottle of water, sprinted back outside and carefully poured it
> over the alternator. The water instantly and loudly flashed into steam. I
> bought another bottle of water, and another. By the time I had poured the
> third litre of water over the alternator, it was merely fizzing rather
> than flashing the water directly into steam.
>
> There was a parts store with a service department one block down the road,
> so I got back in the car and started the engine. The water treatment had
> averted fire danger due to extreme heat, but in the time it had taken me
> to buy the first bottle of water, the alternator had welded itself solid.
> The 3-month-old serpentine belt skidded over the locked-up alternator
> pulley and cooked itself to death in a big cloud of noxious smoke
> during the one-block drive to the service center.
>
> Three hours and $250 later, the car had a replacement alternator and a new
> belt, both of unknown quality.
>
> If this is your idea of a fun diversion during an important trip on an
> unpredictable day, by all means ignore your mechanic.
>
> If it isn't, ask him to be more specific about what's gone bad in the
> alternator. I'm betting he gave the alternator a spin when he removed the
> belt to replace the water pump, and felt a rough bearing.
>
> DS
>
>
YAWN

On Wed, 2 Mar 2005, Bill Putney wrote:

> > ask him to be more specific about what's gone bad in the alternator.
> > I'm betting he gave the alternator a spin when he removed the belt to
> > replace the water pump, and felt a rough bearing.

> Smitty posted a little earlier that both old and new alternators load
> tested at 11V - so it sounds like something else is going on external to
> the alternator.

1) The load test results say nothing about the condition of the bearings.
2) It's entirely possible the load test was not done correctly.

> The dust being thrown from the serpentine belt downstream of the alt.
> pulley piled into a handy little crevice on top of the engine. When I
> opened the hood, the pile of rubber dust was glowing red, just like
> embers in a fireplace. Really weird and amazing.

Fun and amazing after the fact...scary and damned inconvenient at the
time!

Daniel J. Stern wrote:
> On Wed, 2 Mar 2005, Bill Putney wrote:
>
>
>>>ask him to be more specific about what's gone bad in the alternator.
>>>I'm betting he gave the alternator a spin when he removed the belt to
>>>replace the water pump, and felt a rough bearing.
>
>
>>Smitty posted a little earlier that both old and new alternators load
>>tested at 11V - so it sounds like something else is going on external to
>>the alternator.
>
>
> 1) The load test results say nothing about the condition of the bearings.
> 2) It's entirely possible the load test was not done correctly.

But...if the load test is correct, then there's no reason to assume it's
the bearings. But we're both speculating about something we can't prove.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

On Thu, 3 Mar 2005, Bill Putney wrote:

> >>Smitty posted a little earlier that both old and new alternators load
> >>tested at 11V - so it sounds like something else is going on external to
> >>the alternator.

> > The load test results say nothing about the condition of the bearings.

> But...if the load test is correct, then there's no reason to assume it's
> the bearings.

Sure there is: The tech said the alternator is going bad.

Thanks for all your replies. The tech said nothing about the bearings. I
watched him do the load test. Both the new one and the old one had the same
output of 11V. I'm thinking that this unit has a voltage regulator that is
separate from the alternator itself and there is some thing inside the
alternator that keeps it from going too high with out the external
regulator. On the vehicle the output tested low also, although I did not
see him test it. I left the shop (not a Chrysler shop) with these words. If
you think the new one will work put it on. He said he would and that he
would check it after it was installed. If it did not work he said that he
would put the old one back on. My wife picked up the car with a new
alternator. I have not had a chance to check it myself for output but I will
this weekend. The whole thing is still a little of a mystery but thanks to
everyone who replied.

My wife just drove in with the car while I was typing this. I just checked
it out with the new alternator installed. Engine off- the battery measures
12.4V Running it checks 13.9V so I guess all is well. I may never know if
it really needed a new alternator but I'll have to take their word for it.
They have always done the right thing in the past so I guess It's a done
deal.

Thanks again,
Smitty



"Daniel J. Stern" > wrote in message
n.umich.edu...
> On Thu, 3 Mar 2005, Bill Putney wrote:
>
>> >>Smitty posted a little earlier that both old and new alternators load
>> >>tested at 11V - so it sounds like something else is going on external
>> >>to
>> >>the alternator.
>
>> > The load test results say nothing about the condition of the bearings.
>
>> But...if the load test is correct, then there's no reason to assume it's
>> the bearings.
>
> Sure there is: The tech said the alternator is going bad.

Daniel J. Stern wrote:
> On Thu, 3 Mar 2005, Bill Putney wrote:
>
>
>>>>Smitty posted a little earlier that both old and new alternators load
>>>>tested at 11V - so it sounds like something else is going on external to
>>>>the alternator.
>
>
>>>The load test results say nothing about the condition of the bearings.
>
>
>>But...if the load test is correct, then there's no reason to assume it's
>>the bearings.
>
>
> Sure there is: The tech said the alternator is going bad.

No - the OP said: "The shop said that I also had a bad alternator"
(check the original post) as in "already bad". That doesn't imply bad
bearings any more than bad electrical output. Not quite the same as the
shop saying it was "going bad".

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

Daniel J. Stern wrote:
> On Tue, 1 Mar 2005, Smitty wrote:
>
> > I took my 96 grand Cherokee in for a water pump replacement. The
shop
> > said that I also had a bad alternator. It worked fine in our -20
temps
> > here in MN and the warning light has never come on. Do you think it
> > could be bad?
>
> Let me share a story which will help illuminate the matter:
>
> At one time, I drove a very used 1991 ex-police Chev Caprice. One
very
> cold winter morning, I noticed a new noise from under the hood.
Faint, but
> present. Sort of an intermittent hissing/clicking sound coming from
the
> front. I carefully homed in on the alternator as the source of the
noise
> and made a mental note to replace it, for obviously one or both of
its
> bearings had begun to fail.
>
> But life being what it is, I didn't get around to it. Working on cars
is
> very little fun in the winter, and the alternator was continuing to
> charge. I fed a few drops of oil into the front bearing via the shaft
and
> kept on driving, periodically reminding myself that I ought to look
at
> changing the alternator. Eventually I pretty much forgot about it.
>
> About 2 months later, I was on the highway doing about 65mph when a
sudden
> loud noise began to emanate from up front. It sounded like the moan
of a
> dead power steering pump, but it obviously wasn't, for I still had
> steering boost. The noise rapidly grew louder and evolved into a
> hair-raising grinding noise. The voltmeter dropped, the "AMP" light
came
> on, and the smell of very hot metal filled the car. The alternator's
front
> bearing had locked up solid, and the entire bearing was now spinning
in
> its interference fit, meant to keep the bearing's outer ring
stationary in
> the alternator's front housing.
>
> It was still about 3 miles to the next exit. I decided to go for
broke,
> and kept on driving. The grinding sound got ever louder, the stink
of
> broiling metal grew heavier and hotter. I pulled off the highway at
the
> first opportunity, and found...nothing. No service station, no phone
> booth, just an intersection.
>
> Back on the highway, another mile down the road, I pulled off at the
next
> exit, into a gas station's parking area and killed the engine. I
yanked
> the hood release, lifted the hood, and a thick column of smoke poured
up
> from the *extremely* hot alternator. The once-greasy painted brackets
were
> now bare steel, dark pink in color. I ran into the convenience store,
> bought a bottle of water, sprinted back outside and carefully poured
it
> over the alternator. The water instantly and loudly flashed into
steam. I
> bought another bottle of water, and another. By the time I had poured
the
> third litre of water over the alternator, it was merely fizzing
rather
> than flashing the water directly into steam.
>
> There was a parts store with a service department one block down the
road,
> so I got back in the car and started the engine. The water treatment
had
> averted fire danger due to extreme heat, but in the time it had taken
me
> to buy the first bottle of water, the alternator had welded itself
solid.
> The 3-month-old serpentine belt skidded over the locked-up alternator
> pulley and cooked itself to death in a big cloud of noxious smoke
> during the one-block drive to the service center.
>
> Three hours and $250 later, the car had a replacement alternator and
a new
> belt, both of unknown quality.
>
> If this is your idea of a fun diversion during an important trip on
an
> unpredictable day, by all means ignore your mechanic.
>
> If it isn't, ask him to be more specific about what's gone bad in the
> alternator. I'm betting he gave the alternator a spin when he removed
the
> belt to replace the water pump, and felt a rough bearing.
>
> DS

I'm curious Dan. Since the alternator was cooked, was there any core
trade-in value on it towards the new one?

-Kirk Matheson

Well.... The regulator is in the computer, not the alternator shell but
still......

I really have a hard time buying a 'dead' alternator suddenly when you
get a belt changed, especially after all the recent cold weather and you
having no issues.....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Smitty wrote:
>
> Thanks for all your replies. The tech said nothing about the bearings. I
> watched him do the load test. Both the new one and the old one had the same
> output of 11V. I'm thinking that this unit has a voltage regulator that is
> separate from the alternator itself and there is some thing inside the
> alternator that keeps it from going too high with out the external
> regulator. On the vehicle the output tested low also, although I did not
> see him test it. I left the shop (not a Chrysler shop) with these words. If
> you think the new one will work put it on. He said he would and that he
> would check it after it was installed. If it did not work he said that he
> would put the old one back on. My wife picked up the car with a new
> alternator. I have not had a chance to check it myself for output but I will
> this weekend. The whole thing is still a little of a mystery but thanks to
> everyone who replied.
>
> My wife just drove in with the car while I was typing this. I just checked
> it out with the new alternator installed. Engine off- the battery measures
> 12.4V Running it checks 13.9V so I guess all is well. I may never know if
> it really needed a new alternator but I'll have to take their word for it.
> They have always done the right thing in the past so I guess It's a done
> deal.
>
> Thanks again,
> Smitty
>
> "Daniel J. Stern" > wrote in message
> n.umich.edu...
> > On Thu, 3 Mar 2005, Bill Putney wrote:
> >
> >> >>Smitty posted a little earlier that both old and new alternators load
> >> >>tested at 11V - so it sounds like something else is going on external
> >> >>to
> >> >>the alternator.
> >
> >> > The load test results say nothing about the condition of the bearings.
> >
> >> But...if the load test is correct, then there's no reason to assume it's
> >> the bearings.
> >
> > Sure there is: The tech said the alternator is going bad.