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Topic: Testing temp guage

in Forum: C3 Cooling and Heating Systems


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Testing temp guage (1/9)
 4/14/14 1:19pm
dads2vetteLifetime Member
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Ash Fork, AZ - USA

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Just started running the car and after taking it out for a short run the temp gauge read 220.  This was slowly around the block.  Radiator was redone, new engine, hoses and thermostat.  I have not installed the engine compartment seals on radiator shroud.  Electric fan did not turn.  Any ideas on whether this could be a bad reading or can the engine get that hot that quickly?  I have run it for 45 minutes at a time previous to this without any apparent problems. 

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Re: Testing temp guage (2/9)
 4/14/14 11:05pm
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Duncanville, TX - USA

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Not sure at what temp the 'lectric fan should come on, but I would think it should be on before it got to 220*. I'd have to look in da book for the specs.
I always tell folks to not trust the 'lectric gauges to be 100% accurate....they rarely are. Best thing to do is get an infrared(no contact) thermometer and check the actual temps, and compare to what the gauge says.
Did it puke any coolant when you shut it off after that?


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Re: Testing temp guage (3/9)
 4/15/14 12:42pm
rraider1
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Woodland, WA - USA

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I think most kits use either a 185 or 195 thermo sws. some have adjustable 170 to 210 some may have a 200 deg.

two notes I noticed one do not use thread tape on thermo sw

Best option is to have the fan pull air.

You do not want your fan to be running at cruising speed.




Re: Testing temp guage (4/9)
 4/15/14 12:58pm
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Duncanville, TX - USA

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Dave...does your car have a regular fan with a fan clutch, in addition to the 'lectric fan? If so, your fan clutch may not be werkin properly at speed...

that...and the fact that the trans is not shifting could contribute to the higher engine temp than "normal"....Wink

|UPDATED|4/15/2014 9:58:27 AM (AZT)|/UPDATED|


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Re: Testing temp guage (5/9)
 4/15/14 1:13pm
HighDesertDave
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In the good old days we'd take a cold engine, remove the rad cap, put mom candy thermometer in the coolent, start the engine and see what happens. When the thermostat opens after running a bit the temp will start to rise at the rad as the thermostat starts to flow. We'd note at what temp (using both the cars temp gauge and candy thermo) this happened. The dash gauge should read higher since its sensing trapped heated coolant. Then continue to monitor. As the thermostat opens fully you can see grater fluid more movement in the open rad. Again, you compare the candy thermo to the gauge in the car. At some point everything should stabilize. When it gets warm enough the clutch fan will start to engage...you can hear this take place. It becomes louder as it picks up R's when engaged. Make another notation. Somewhere in there, the electric fan should come on before the rad starts to boil. With the cap off, you gotta be ready for expansion/boil.
Pretty easy to compare and test all components. Dave

|UPDATED|4/15/2014 10:13:07 AM (AZT)|/UPDATED|


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Re: Testing temp guage (6/9)
 4/15/14 2:05pm
rraider1
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Woodland, WA - USA

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the 1980 electrical troubleshooting say the electric cooling fan comes on at 238 deg.

accuracy for the temp gauge has caused a lot of discussions, the newer temp senders do not match up to the original GM senders.

here is one set of info

http://willcoxcorvette.com/instructions/Temperature_gauge_help_page_NEW_Revised_R3.pdf

Re: Testing temp guage (7/9)
 4/15/14 5:31pm
dads2vetteLifetime Member
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Ash Fork, AZ - USA

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Car has the regular fan without clutch.  I haven't seen the electric fan ever work and both are/would be pulling air through the radiator.  I like the idea of the candy thermometer and will give that a try.  Now that you mention the high rpms, that would definitely explain the quick increase in temp.  I did notice on a subsequent test drive the temp did drop slightly, I would assume that was the thermostat opening.

Thanks  


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Dave C..........My mantra: I can not be bought!!      Long and short term leases available.
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Yeah, I know, Shut up Dave.
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Re: Testing temp guage (8/9)
 4/15/14 6:47pm
joey4fingers
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Honeoye Falls, NY - USA

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Hey! A fellow western New Yorker! Hi Dave. We've all chased our tail at one time or another on this one, so don't rule out that just because the thermostat is a new one that it is actuating correctly. It may be cracking open a little instead of opening fully or could also be sticking. It only takes the smallest of burrs to make one hang up. Good luck!

P.S. - Saturday and Sunday's weather was just a tease.



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Re: Testing temp guage (9/9)
 4/15/14 10:29pm
tb2k82ceLifetime Member
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Lemon Grove, CA - USA

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Harbor Frieght sell a relatively inexpensive infrared thermometer.  I purchased one and check my system out.   Of course I also have an oil temperature meter after a while they will match each other also.  

But the infrared thermometer is a nice toy to have.
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