Factory water temp gauge sending unit

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Factory water temp gauge sending unit

Postby day2vega » Wed Jun 15, 2016 6:39 pm

Vega Gt
Anyone know the ohms readout for the water temp gauge sending unit
cold reading...I was told 700 ohms cold, I picked one up and it reads
505 ohms. Course it came from Napa they said it was correct.

Thanks
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Re: Factory water temp gauge sending unit

Postby spencerforhire » Thu Jun 16, 2016 7:12 am

700 cold sounds about right, but "cold" is not a precise term; it might be 700 @ 50f and 550 @ 70f. Apparently, GM used a bunch of different senders in the 70's, with variations between both years and platforms. I think I have a 76 GT sender somewhere I can test.
Also to confuse things, a sender will produce varying readings dependant upon where it's installed. In the cylinder head of an SBC between #1 and #3 will result in the highest reading on the gauge, then in the front coolant passage of intake manifold a bit lower, then in the water neck housing lowest of all, only producing an accurate reading when the thermostat opens.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

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Re: Factory water temp gauge sending unit

Postby day2vega » Thu Jun 16, 2016 8:46 am

Thanks spencer
Your correct cold is not precise, I tested the unit at work after it had been in my pocket couple hours 500 ohms
I left the unit on the counter after work over night and just tested the unit this morning ohms readout
is 690...so, how do I really know if the unit is correct or not?

Thanks
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Re: Factory water temp gauge sending unit

Postby Monza Harry » Thu Jun 16, 2016 4:53 pm

day2 I would just install it as it seems close to stated specs. It will be easy enough to check, and or change after the fact, just fire it up and break out the non-contact temp probe and compare to the gauge. The gauges are notoriously accurate with only 2 numbers on them [Monza I don't have a Vega to check but I can't see them being any fancier] Ice cold and Holy :cuss: :censored: , it is TOO LATE! :lol: Harry As an example only but how can you beat those prices? http://www.harborfreight.com/catalogsea ... q=Temp+Gun
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)
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Re: Factory water temp gauge sending unit

Postby day2vega » Thu Jun 16, 2016 6:28 pm

Thanks Harry
Motors not ready to fire up, I'm just stock piling
parts for my build.
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