Alternator is too hot?

Tiny
ALPHAA10
  • MEMBER
  • 1998 BUICK LESABRE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 252,000 MILES
Driving through heavy Monday afternoon traffic, moving about 35 MPH, my power steering vanished, leaving the steering barely responsive. Glancing at the instrument panel, I found my engine had stalled, with instrument panel warnings of Oil and Volt.

After I braked slowly to a stop (with nobody behind me), I shifted to Park, restarted the engine, and drove home. In the driveway, with the engine off, I checked voltage at the battery terminals with my VOM (12.67v), then started the engine to check charging voltage (14.47v).

The alternator was very hot to the touch, so hot that, after cooling for an hour with the hood raised, I could not leave my hand on the alternator housing for more than 10 seconds.

This is not normal engine/alternator behavior. Four weeks ago, I replaced the car's four-year-old battery (one dead cell) and bought and installed a new alternator of premium quality (O'Reilly's Ultima battery). No problems until now, but today's event indicates not all problems with this engine have been addressed.

Tomorrow, I'll take the car to O'Reilly's for a battery load and alternator test and perhaps an error code scan. Until then, I have no further information.
Monday, September 25th, 2023 AT 8:52 PM

15 Replies

Tiny
JACOBANDNICKOLAS
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Hi,

To some degree, the alternator will be hot. The combination of under hood temps and producing a current causes heat.

Let me know the results of the tests done at the parts store. I'm interested in knowing.

Take care,

Joe
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Tuesday, September 26th, 2023 AT 1:14 PM
Tiny
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Today, at noon, I asked the alternator's point-of-sale to test the battery and alternator. On checking, their equipment passed both alternator and battery. That result was reassuring, but several hours later, after a typical day's driving, the alternator was still very hot after the engine had been shut down for a few minutes.

Tomorrow, after driving, I plan to check the same alternator with a remote-sensing thermometer, so I can have a specific and accurate record of temperature. Then, call the OEM to determine the normal operating temperature range.

My concern is all electrical components face shorter lives when under temperature stress. Some components are designed for high temperature operations, of course.
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Wednesday, September 27th, 2023 AT 10:39 PM
Tiny
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Hi,

Thanks for the update. I suspect it is hot from use and under hood temperatures. However, I like your idea. It's a good one.

Let me know what they tell you. I am interested in knowing the temperature and what the manufacturer considers normal.

Take care,

Joe
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Thursday, September 28th, 2023 AT 8:03 PM
Tiny
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Yesterday afternoon, I bought the laser-based thermometer, but have not applied it yet.

In case the alternator OEM says the unit operates at normal temperatures, I have another plan-- reinstall the original alternator to see whether any symptoms improve. I did not have any known problem with the original alternator, and that original unit tested okay at O'Reilly's.

Yesterday, the car stalled twice in the hottest part of the day-- 6-8pm-- after an afternoon of waiting at traffic lights and moving slowly through traffic. During each stall, the instrument panel was dark except for VOLT and OIL indicators. In recovery from each event, I made sure the car had stopped, then shifted to PARK to restart the engine, which started easily each time.

Thanks for checking in!

* I have checked 2carpros.com for similar Buick LeSabre behaviors--
https://www.2carpros.com/search?q=buick+lesabre+1998+stalls+in+traffic&key=added&header=yes
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Friday, September 29th, 2023 AT 12:53 AM
Tiny
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Today, I called the OEM, gave him all the symptoms-- but without laser temperatures, which I have not had a chance to check, yet. The customer tech support representative agreed it appears the new alternator might have a defective regulator.
Although I have to disappear for a few days while I complete a computer upgrade project for a customer, I'll be back in touch, soon.
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Friday, September 29th, 2023 AT 3:40 PM
Tiny
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After completion of the computer project, I am back.

With a noontime check of the alternator after an hour of city traffic, using the new laser thermometer, I determined during several scans that the alternator running temperature is 147F. After one hour, with hood raised for ventilation, the temperature drops to 119F.

This temperature value was given to a tech support specialist for O'Reilly alternators, who said 147F sounded normal. The rough rule-of-thumb, he said, is the alternator tends to match engine temperature.

Of course, that ignores the issue of repeated engine stalls during low-speed, rush-hour drive, with many stops, idling at a traffic light. These did not occur before the new alternator.

So, the plan is to continue use of the new alternator, to see whether the stalls return, and then (in either case) replace the new alternator with the original (which O'Reilly already has tested OK). At that point, monitor the old alternator for temperature and any stalls. At least, that is a basis for comparison.

Frankly, I already suspect the new alternator has voltage regulator problems. But a completed diagnostic process helps confirm direction.
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Tuesday, October 10th, 2023 AT 8:59 PM
Tiny
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Hi,

Thanks for the update. I have a feeling the temps are normal as well. As far as the voltage regulator is concerned, that is a different one. LOL It could be faulty.

If you have a chance, let me know if the original one is the same when you reinstall it.

Take care,

Joe
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Wednesday, October 11th, 2023 AT 6:57 PM
Tiny
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Would an in-store alternator test always detect a faulty voltage regulator?

Previously, I had supposed it would, but your answer suggests that it might not. A voltage regulator, like other electrical components, can have intermittent faults.

In which case, that could explain how a new alternator could stall an engine repeatedly, but next morning, after a night of rest, test "flying colors" when I had the point-of-sale store test its own brand.

Your have raised an important question-- awaiting your response.
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Thursday, October 12th, 2023 AT 8:34 PM
Tiny
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Hi,

Absolutely, that can be an issue. Intermittent issues can always cause a false positive. If things are working properly when checked, they will test good. But as you mentioned, the part can fail at a different point.

Let me know.

Joe
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Thursday, October 12th, 2023 AT 9:03 PM
Tiny
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Predictably, with the arrival of cool fall temperatures, the alternator gremlin went on a vacation, with not even a hint of a problem. I'll let you know if anything changes.
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Saturday, October 21st, 2023 AT 10:22 PM
Tiny
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Hi,

Thanks for the update. So, the cooler weather has eliminated the problem? This is a two-sided sword. It's good the problem is gone, but what was causing it when the temperature outside was higher? Let me know if things change. I'm interested in knowing.

Take care,

joe
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Saturday, October 21st, 2023 AT 10:34 PM
Tiny
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Thanks, Joe, for all your help during the past year!
Merry Christmas and Happy New 2024.
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Friday, December 22nd, 2023 AT 1:42 AM
Tiny
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OMG! You are so welcome and thank you for thinking of me. I've answered over 100,000 posts, and you are the first. It is really nice of you.

Take good care of yourself and I wish you a Merry Christmas and a great new year!

Joe
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Friday, December 22nd, 2023 AT 7:02 PM
Tiny
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Joe, the alternator gremlin struck again, but this time on a cool day, after only a modest amount of city driving. The gremlin did not return, but I am watchful.

To search for malfunctions, I requested a scan at two local auto parts stores (to provide a check of one scan against the other, with each store using a different scanner brand), but neither scan showed any alternator issue.

However, the scans agreed my engine had other issues--

Scan Issue 1--
Error P0304-- misfire on cylinder 4. In checking this error with my local auto parts store, I was offered a single spark plug for a replacement, but since the old rule is to replace all plugs at the same time, do you recommend I replace all six plugs? (Of course, I can diagnose with only a single plug to determine whether it makes a difference.)

Scan Issue 2--
Error P0404-- EGR open position performance
Error P1404-- EGR closed position performance
On these errors, I was puzzled, since the EGR valve is indicated both stuck open and stuck closed, Possibly, the valve is so dirty, it will wander slowly between open and closed. A new replacement valve is somewhat expensive, so I would prefer to take the valve assembly apart, and clean it like a dirty carburetor, with carb cleaner spray and small, stiff brush. Will that work? Do you recommend an overnight "soak" in cleaner, and if so, what cleaner?
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Thursday, February 1st, 2024 AT 11:24 AM
Tiny
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Hi,

I need to ask a favor. We need to start a new post for this issue. We try to keep them specific to one problem per post, so they are more helpful to others. I hope you understand.

Here is the link to start a new one. Just copy and paste your question.

https://www.2carpros.com/questions/new

This sounds like a wiring issue and the misfire is likely a result.

Again, I hope you understand.

Take care,

Joe
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Thursday, February 1st, 2024 AT 6:34 PM

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