87 Turbo Esprit - high voltage ~14.7V - Page 2 - LotusTalk - The Lotus Cars Community
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post #21 of 30 (permalink) Old 11-15-2018, 06:55 PM
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I just bought this rebuilt Bosch alternator on eBay and have installed it while I had the engine out of the car. There's no mention of the Bosch model number, but I've attached a photo of the unit as it appeared on eBay. Is this the AL49X?

Of note, Eddie, there was a tag attached to the pole on the alternator that advised to run a 4-gauge wire direct from the positive battery post to the pole, while leaving all other prior connections in place...which I've done. Might this be something to consider?

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post #22 of 30 (permalink) Old 11-16-2018, 09:15 AM
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I've not had good luck with lighter socket voltmeters, the readings vary. Use a quality meter at the battery to check the other gauge(s).

With newer vehicles, you have the complexity of ECU controlled charging, where the ECU may lower charging load for fuel consumption reasons , or run higher boost voltages after a start, then ramp down to a lower float voltage.

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post #23 of 30 (permalink) Old 11-16-2018, 10:39 AM
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Originally Posted by BobWeber View Post
I just bought this rebuilt Bosch alternator on eBay and have installed it while I had the engine out of the car. There's no mention of the Bosch model number, but I've attached a photo of the unit as it appeared on eBay. Is this the AL49X?

Bob
My AL49X didn't have any red on it. Mine also had an AL49X sticker on the side of it. Pics can be seen here:
https://www.lotustalk.com/forums/f16...edures-438897/

Jim S.
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post #24 of 30 (permalink) Old 11-16-2018, 11:44 AM
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Definitely get a good, accurate voltmeter and check the voltage right at the output post of the alternator and then right at the terminals of the battery. They should be within a few tenth's of each other. Any large difference means bad connections or under-sized wiring. It must be done with the motor running at least 1,000 RPM's with some load like the headlights on. With the motor off and a good battery you would expect to have at least 12 volts and maybe as much as 12.5. With the motor running you should not get above 13.5 unless the battery is dead or badly connected. The battery is also necessary to prevent the voltage from getting very high along with the voltage regulator. Typically dash instruments are not very accurate, especially when they get old.
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post #25 of 30 (permalink) Old 08-24-2019, 10:51 PM Thread Starter
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I realize this is a 10 month old thread, but have a puzzling update.

My 87 Turbo Esprit has been running fine for the last ~2K miles in 10 months despite this 'broken' Smiths volt meter.
It pegged at 15V (although other digital meters show 14.7V.

Now, I had car in shop for totally unrelated issue (exhaust pre-cat and catalyst remove and replace).

When it came back, the alternator light was now flickering - it would go BRIGHT RED on higher than idle and my digital voltmeter plugged into cigarette lighter was show 15.1V (higher than the usual 14.7V).

I was panicking because I wanted to use the car at Monterey Car Week (about 200 miles round day trip).

No wires were disturbed during exhaust work - in fact, no significant wires in the area or work.

Then it happened: after 3 days, the flickering went 100% away AND the Smiths (Tudors?) voltmeter started reading much closer to actual vs. pegged at 15V most of time.

Nothing was changed or adjusted - it just 'went away'.

SMH.

Eddie B
87 Esprit 'SLEEK GT'

Last edited by sleekgt; 08-26-2019 at 09:00 PM.
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post #26 of 30 (permalink) Old 08-25-2019, 10:35 AM
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Check for black goo on the bottom of the alternator. Sounds like the voltage regulator is going bad and/or the brushes in the alternator are sticking.
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post #27 of 30 (permalink) Old 08-25-2019, 08:40 PM Thread Starter
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Check for black goo on the bottom of the alternator. Sounds like the voltage regulator is going bad and/or the brushes in the alternator are sticking.
David Teitelbaum
It was converted to Bosch 49 ALX so no black goo involved. Still suspect the voltage regulator as that's the only part that would display the randomness.

Eddie B
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post #28 of 30 (permalink) Old 08-26-2019, 09:41 AM
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Voltage readings taken directly at the alternator and battery should confirm the actual output, but I suspect you've already done that. I agree that it pretty much has to be the VR, and unfortunately the less than accurate stock voltmeter won't help you closely monitor it.
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post #29 of 30 (permalink) Old 08-26-2019, 09:01 PM Thread Starter
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Voltage readings taken directly at the alternator and battery should confirm the actual output, but I suspect you've already done that. I agree that it pretty much has to be the VR, and unfortunately the less than accurate stock voltmeter won't help you closely monitor it.
Voltage reading was taken directly off the battery leads. But now the voltmeter is 'accurate' - a bit unnerving- if problem can disappear randomly,it can reappear randomly.

Eddie B
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post #30 of 30 (permalink) Old 08-27-2019, 05:38 AM
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One thing I've not seen mentioned is that any resistance (corrosion) between the battery and alternator sense lead or ground can result in overcharge as the alternator compensates for the resistance in the circuit. I'd look carefully at the charging circuit wiring and how good the connection to the battery terminal clamps is.
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