Atwell, last weekend I went through a test which you might find
interesting. Put a new sender in a pot of water on the stove to measure
temp vs resistance. I think many of our cars use the same senders (at
least TR5-8, Spits and GT6s). Here is what I found (hope these columns
line up).
res (ohms) deg C deg F
500 42.0 107.6
450 46.0 114.8
350 49.0 120.2
250 55.0 131.0
200 61.0 141.8
150 70.0 158.0
100 92.0 197.6
Then my VOM started going funny. I thought it might be from the leads
getting hot from being in contact with the hot sending unit. So I
measured (with different leads) as the water was cooling:
res (ohms) deg C deg F
70 78.0 172.4
100 68.0 154.4
125 60.0 140.0
150 52.0 125.6
180 50.0 122.0
380 48.0 118.4
I live at about 2000' above sea level so the boiling point is lower than
212 F (100 C). Never did get to the 50 ohm value you saw.
(This was a brand new Intermotor sending unit from TRF - I have not
tested my old one yet but it seems to show on the low side, never gets
above 1/4
unless idling in hot summer weather, then maybe almost 1/2).
( If you recall my earlier post on this, the gauge reads 1/4 at 200
ohm, 1/2 at 100 ohm and 4/4 at 50 ohm. Unfortunately when I did this
test, I connected the gauge to the battery directly without going
through the voltage regulator. As I can't get to my car 'til the weekend
to redo this part of the test properly, I don't have the actual voltage
regulated values for the gauge. )
Peter Zaborski
76 TR6 (CF58310 UO)
Calgary AB Canada
> -----Original Message-----
> From: Atwell Haines [SMTP:carbuff@scooter.net]
> Sent: Tuesday, March 10, 1998 12:37 PM
> To: triumphs@autox.team.net
> Subject: RE: Spitfire Temp gauge (repeat)
>
>
> I just installed the new sending unit for the temperature gauge, and
> it
> works fine now.
>
> So in case anyone else has this problem, the resistance of a working
> sender
> is:
>
> COLD: 1000 ohms
> HOT: 50 ohms
>
> Measurements were taken with the sender wire diconnected, terminal to
> block, with a digital VOM.
>
> Atwell Haines
> '79 Spitfire FM96062 UO (On the road soon!)
>
> "47.5% of all statistics are made up on the spot."
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