Temp In Relation To Gauge

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Offline Shep69

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Temp In Relation To Gauge
« on: November 21, 2021, 10:04:52 pm »
Does anyone have a 69 and could tell me where the temp gauge needle sits when the engine temps at 190deg F / 88 C .
TIA

Offline jiffy

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Re: Temp In Relation To Gauge
« Reply #1 on: November 23, 2021, 02:28:14 pm »
Can't tell you that, but if you pull the wire off the top of the sender, what colour is the sleeve around the electrical post - green, white, red or black?





for a '69, it should be red.


« Last Edit: November 23, 2021, 02:30:17 pm by jiffy »
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Offline scollist

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Re: Temp In Relation To Gauge
« Reply #2 on: November 23, 2021, 05:29:17 pm »
From other googling it looks like 190 degrees is the standard thermostat (at least for a 351W).  If this was the case I would want the needled to be just over half way when this point is hit.  That way if the engine is getting hotter (say on a 40 degree day) and not cooling well you will see it go higher (I expect that it would max out somewhere near 220 degrees - and if it up there you want to know  about it!!).

If it was at half or a bit less that would be okay too - get yourself one of the Laser Thermometers so you know what temp it is at relative to your gauge.  E.g. https://www.ebay.com.au/itm/284361017175?hash=item42353cc757:g:eYUAAOSwxqlg-3V8

Offline GEOFF289

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Re: Temp In Relation To Gauge
« Reply #3 on: November 23, 2021, 07:31:32 pm »
Or get one of these and have peace of mind. Tells you the block temp rather than the coolant and you can set the alarm to warn you when things are getting too hot.

http://enginewatchdog.com/

Even operating correctly the gauge tech in these old cars - a '69 may be better than my old girl - will only tell you a vague story at best.


Offline J.hatzivalsamis

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Re: Temp In Relation To Gauge
« Reply #5 on: November 24, 2021, 10:25:24 am »
I have gone down this road and as Geoff 289 said get an engine guard and set your alarm to the desired temp and have a stress free experience.

Offline Shep69

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Re: Temp In Relation To Gauge
« Reply #6 on: November 25, 2021, 04:58:11 pm »
Thanks for the replies guys. As im running fuel injection i do have the temp reading on the handheld verified correct from my fluke temp gun.
I have an adjustable voltage regulator under the dash for the gauges so i just needed to know were the needle should sit around running temp.
I filled the fuel tank yesterday and got the motor up to running temp and adjusted the regulator.
So now the fuel reads full and the temp needle is in the middle at 190 deg.   :pepper:
« Last Edit: November 25, 2021, 05:04:36 pm by Shep69 »

Offline scollist

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Re: Temp In Relation To Gauge
« Reply #7 on: November 25, 2021, 05:43:45 pm »
Great work!!  :bow:

I had issues when I first got my car with it showing that it was overheating. Turned out I had a late 65/66 temp sender in a 4V manifold, but had the early 65 sweeping dash which needed the early 65 temp sender (the skinnier one).  Replaced the sender with an adapter and it reads perfect.

For my fuel tank - I did a lot of trial and error to bend the sender arm to the right position. It reads perfectly now - BUT an adjustable voltage regulator would've been fantastic!! 

Where do you get one of these adjustable voltage regulators? (just for info).

Offline 67FBGT

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Re: Temp In Relation To Gauge
« Reply #8 on: November 25, 2021, 06:25:37 pm »
Well, I never twigged that there are 4 different sender units - duh!  :thud: One can learn something new every day...

Is there a schedule somewhere that tells us which unit is required for which engine spec? I have a 302 with 4V. The sender unit is white.
TIA

Offline scollist

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Re: Temp In Relation To Gauge
« Reply #9 on: November 26, 2021, 09:35:44 am »
67FBT - This article (originally from Mustang Monthly I think) might help.

https://forum.mustang.org.au/index.php/topic,12082.0.html

You could also look at https://www.motortrend.com/how-to/mump-1303-how-to-diagnose-gauge-problems/.

Essentially you need to know the high resistance level that will show 'low' on the gauge, and the low resistance level that will show 'high' on the gauge, and then match the sender to that.  You can use a resistance wheel with a full 12 volt feed to the gauge to determine the resistance levels that the gauge wants (i.e. bypass the sender - but make sure you are still going via the voltage regulator - as the gauges only expect a 5 volts, not 12 volts. A bit of Ford legacy).

Offline 67FBGT

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Re: Temp In Relation To Gauge
« Reply #10 on: November 26, 2021, 06:03:32 pm »
Thanks Scollist! I will test my temp sender unit and see what's what.
Interesting the Mustang Monthly comments about the ammeter, as in being basically a fire risk. I had heard that and disconnected mine long ago as it never worked anyway. Would be nice to get it going though, maybe converted to a voltage gauge instead.

Offline scollist

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Re: Temp In Relation To Gauge
« Reply #11 on: November 27, 2021, 08:54:34 am »
Here is the resistance wheel I was talking about - it goes in place of the sender unit.
https://www.jaycar.com.au/resistance-wheel/p/RR0700

Unfortunately it looks like Jaycar no longer sells them though. Bummer.  I'm not sure if any of these would be an alternative - https://www.ebay.com.au/b/Resistance-Capacitance-Inductance-Decade-Boxes/183485/bn_55158878.  The other option would be to make one using a potentiometer, a piece of board to mount, and a couple of alligator clips - if you know the upper and lower resistance I'd assume that points in between when rotating would be linear (but I'm no expert here).