another voltage question

Technical advice Q&A

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alfred
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Joined: Wed Sep 17, 2014 11:13 pm
Location: london ontario
Canada

#1 another voltage question

Post by alfred » Sat Jun 09, 2018 11:11 pm

I checked the archives but still have to ask what is going on. A few day ago my water temp gauge started reading high -205 instead of the usual 185- and my tach showed revs about 1100 higher than actual (I have a small tach that shows real RPM) and the stock tach has read 600 high for two years. I'm sure the engine is not running hot because the new Coolcat rad and coolcat fan switch cycle on and off as usual when I'm idling. I figured it would be the voltage regulator so off to NAPA and I get an exact replacement to the previous one used. Still tach and temp are reading high. Can the alternator be causing this? VR is a Wilson 62-03-2604

Thanks, Alfred
1968 2+2

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Tom W
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#2 Re: another voltage question

Post by Tom W » Sun Jun 10, 2018 9:29 am

Measure the battery voltage using a multi meter with the engine off, at idle and at a 2000rpm. This will tell you what your alternator is doing. Also, measure the voltage at the voltage stabiliser to see whether that’s working correctly.
Tom
1970 S2 FHC

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mark10337
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#3 Re: another voltage question

Post by mark10337 » Sun Jun 10, 2018 10:48 am

I had a similar problem recently. Traced to bad earth connections. Where the gauges are concerned, there is an earth connected to the copper plate of the centre dashboard. Test this for connectivity through to chassis earth on it's own, and all other earth connections in the area.
-Mark

1969 Series 2 OTS, Regency Red
'Life's to short to drive a boring car'

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Topic author
alfred
Posts: 34
Joined: Wed Sep 17, 2014 11:13 pm
Location: london ontario
Canada

#4 Re: another voltage question

Post by alfred » Tue Jun 12, 2018 4:15 pm

I checked the earth connections at the center dash and all was good there.
Voltage at the battery was 13.3 , then 14 at idle, and 15 at 2,000 rpm
At the regulator one terminal was 14.5 at idle, and 15 at 2,000 rpm
second terminal bouncing 11 - 13 V at 2,000 rpm

the 15 V seems to within spec according to my manual - no adjustment is available on the solid state VR unit

Any other electrical ideas that would cause the water temp and rpm to be punched up higher?


Alfred
1968 2+2

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Topic author
alfred
Posts: 34
Joined: Wed Sep 17, 2014 11:13 pm
Location: london ontario
Canada

#5 Re: another voltage question

Post by alfred » Tue Jul 03, 2018 10:12 pm

Half the problem solved. I removed the temp sender and bench tested it with a spare battery. It still read +20F too high, so the brand new sender was the problem. Bad right out of the box. I got another new sender and bench tested it before installing and it read spot on. The tach must be just slowly failing on its own and I mistakenly thought both issues were related to voltage. Onward to the next thing... there always is one. Right now it is just too hot to drive, record high temps and no AC in the car. :cussing:

Alfred
1968 2+2

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