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Topic: Testing temp guage

in Forum: C3 Cooling and Heating Systems


Testing temp guage

Posted: 4/14/14 10:19am Message 1 of 9
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Ash Fork, AZ - USA
Joined: 4/18/2007
Posts: 1058
Vette(s): 1981 Red Interior White exterior
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. 


Dave C..........My mantra: I can not be bought!!      Long and short term leases available.
In the words of Zora Arkus-Duntov "Is your seat belt fastened? Alright, Let's go"


Yeah, I know, Shut up Dave.
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Re: Testing temp guage

Posted: 4/14/14 8:05pm Message 2 of 9
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
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?



Joel Adams
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Re: Testing temp guage

Posted: 4/15/14 9:42am Message 3 of 9
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Woodland, WA - USA
Joined: 10/14/2003
Posts: 1171
Vette(s): 1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

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

Posted: 4/15/14 9:58am Message 4 of 9
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
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|



Joel Adams
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Re: Testing temp guage

Posted: 4/15/14 10:13am Message 5 of 9
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Carson City, NV - USA
Joined: 12/4/2013
Posts: 239
Vette(s): Numbers matching 1972 350 4 speed, silver pewter body with blue interior
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|



My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

Re: Testing temp guage

Posted: 4/15/14 11:05am Message 6 of 9
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Woodland, WA - USA
Joined: 10/14/2003
Posts: 1171
Vette(s): 1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

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

Posted: 4/15/14 2:31pm Message 7 of 9
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Ash Fork, AZ - USA
Joined: 4/18/2007
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Vette(s): 1981 Red Interior White exterior
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  



Dave C..........My mantra: I can not be bought!!      Long and short term leases available.
In the words of Zora Arkus-Duntov "Is your seat belt fastened? Alright, Let's go"


Yeah, I know, Shut up Dave.
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Re: Testing temp guage

Posted: 4/15/14 3:47pm Message 8 of 9
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Honeoye Falls, NY - USA
Joined: 9/16/2012
Posts: 10
Vette(s): 1980 Coupe, T-Tops, Red, 4-Speed, ZZ4 350 from Chevrolet Performance.

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.




Re: Testing temp guage

Posted: 4/15/14 7:29pm Message 9 of 9
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Lemon Grove, CA - USA
Joined: 10/17/2007
Posts: 2041
Vette(s): 1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.
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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