Alternator issue

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se6b
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Alternator issue

Post by se6b » Fri Sep 18, 2020 4:07 pm

Hi all!

Wonder if anyone could shed some light on this...

Scimitar SE6B

Noticed the other day that the temp gauge was sitting around 105-110 degrees which is unusual as it normally sits bang on the 90 mark.

The voltmeter hasn’t changed reading, however it reads around 14V on the gauge all the time. Battery measures around 12.6V engine off and 14.2V engine idling and same at 2000rpm.

Do those readings sound normal or is it likely there is a charging issue with alternator or over charging etc.
Occasionally the ignition light doesn’t extinguish after engine start, but goes out if you increase revs to around 2000rpm. Normally the ignition light stays off after that, but occasionally I have seen a flicker while idling or whilst driving at various rpm’s.

Just wondered if anyone has any suggestions or ideas. I’m a newbie so not sure what’s completely normal for my car yet.

Many thanks!
Last edited by se6b on Fri Sep 18, 2020 4:10 pm, edited 1 time in total.



se6b
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Alternator issue

Post by se6b » Fri Sep 18, 2020 4:09 pm

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philhoward
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Alternator issue

Post by philhoward » Fri Sep 18, 2020 5:15 pm

Voltage readings sound about right but the first port of call could be the instrument voltage regulator- quick test is with the engine not running (ignition on) the fuel and temp gauges usually read about 5-10% lower (a needle width or so) if it’s faulty.


Phil Howard
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se6b
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Alternator issue

Post by se6b » Fri Sep 18, 2020 11:57 pm

philhoward wrote:
Fri Sep 18, 2020 5:15 pm
Voltage readings sound about right but the first port of call could be the instrument voltage regulator- quick test is with the engine not running (ignition on) the fuel and temp gauges usually read about 5-10% lower (a needle width or so) if it’s faulty.
Thanks for responding Phil. So if all the gauges read slightly lower with engine off(ignition on), than with engine running there is a problem with the instrument regulator? Would it have to be noticeable on all four gauges?



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philhoward
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Alternator issue

Post by philhoward » Sat Sep 19, 2020 5:59 am

Only fuel and temperature as only they use it.

Consider the theory - if when fed with a 10V supply, a gauge sits at half way. If fed with 12.5V, it should read 25% more (about 5/8 on the gauge). If fed with 14V it will be 40% high (around 11/16ths on the gauge) What that test does is try and prove the latter two are happening.

Best confirmation for not overheating is an infra red temperature gauge.


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peter freeman
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Alternator issue

Post by peter freeman » Sat Sep 19, 2020 8:14 am

If its too hot the rad fan would be running - is it. Moe than likely its the regulator as Phil has suggested - perhaps its lost the earth connection



phade
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Alternator issue

Post by phade » Sat Sep 19, 2020 9:16 am

The battery voltage readings appear to be normal.

My Rialto 2 has got the same Smiths voltage meter as your's and I found that over tightening it's terminals can cause it's needle to stick.



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Alternator issue

Post by Scim8tar » Sat Sep 19, 2020 9:38 am

Regarding your charge light coming on, if it's coming on at various rev's the alternator could be on it's way out, brushes worn or diode failing, just had a modern car with those symptoms that was putting a.c waves out and throwing up body module faults, on classic's with worn V belts i have known them to oscillate around the alternator and water pump pulley's (slipping) at certain revs putting the charge light on briefly.



se6b
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Alternator issue

Post by se6b » Mon Sep 21, 2020 12:39 am

Thanks for all your replies.

Fan appears to run normally, but if checking engine temperature with an infra-red laser thermometer, where is the best place to aim in order to get the most accurate reading and then compare with the temperature gauge on the dashboard?

Is it normal for my dash voltmeter gauge to read as it does at around the 14-14.5V range?



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philhoward
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Alternator issue

Post by philhoward » Mon Sep 21, 2020 5:55 am

se6b wrote:
Mon Sep 21, 2020 12:39 am
Is it normal for my dash voltmeter gauge to read as it does at around the 14-14.5V range?
Yes, as per my original reply.


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Alternator issue

Post by scimjim » Mon Sep 21, 2020 4:57 pm

se6b wrote:
Mon Sep 21, 2020 12:39 am
if checking engine temperature with an infra-red laser thermometer, where is the best place to aim in order to get the most accurate reading and then compare with the temperature gauge on the dashboard
i aim it right at the brass head of the temp sender and calibrated my gauge to that - it runs at 90 deg plus/minus a couple constantly.


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se6b
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Alternator issue

Post by se6b » Mon Sep 21, 2020 11:40 pm

I’m starting to think that my ignition light is on all the time but it’s very faint and can’t really be seen in daylight when driving.

It’s on at idle and then gets dimmer until around 2000rpm where it’s either too faint to see or completely extinguished. As soon as the revs drop below 2000rpm though it does the opposite and increases in intensity until at idle it’s on again fully.

Thanks for all your comments above. Will investigate further. This is all new to me, but happy to learn!!



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Dennis Nicholas
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Alternator issue

Post by Dennis Nicholas » Tue Sep 22, 2020 12:30 am

se6b wrote:
Mon Sep 21, 2020 12:39 am
Thanks for all your replies.

Is it normal for my dash voltmeter gauge to read as it does at around the 14-14.5V range?
Your original statement about voltmeter "it reads 14V all the time" !!! Ignition on engine stoped meter should show around 12 to 13 V and only rise to around 14 once engine on and running above about 1,000 revs.
Best bet is to get one of the electronic regulators.......fairly easy to change from the old canister type with contacts inside that make and break due to heat generated by the current flowing through them. The canister is mounted behind the dash in front of the steering wheel.....not to be confused with the indicator canister beside it. I used the CCVS1 from keith@fenwick40.freeserve.co.uk www.freewebs.com/classicstabilizers/
But that was some time ago so both may be no longer valid
Also change the flasher to an electronic while you are at it.

Dennis


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Dennis Nicholas
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Alternator issue

Post by Dennis Nicholas » Tue Sep 22, 2020 12:40 am

Also look at recent subject "SE6a alternator/ignition light"........brushes in the alternator......regulator in alternator.
The regulator we are talking about behind the dash is the one that supplies a steady 10 Volts to the fuel and temperature gauges to make them read correctly no mater what the alternator is pushing out.

Dennis


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