Temp Gauge Position vs Actual Temps - The 1947 - Present Chevrolet & GMC Truck Message Board Network

raoul.duke · 08-23-2006, 04:32 PM

Been getting some high temp readings (to the first 'H' bar) out on the highway and have been reading the posts on bad sending units, which made me wonder-

How do the gauge positions correlate to actual coolant temperature? Example- a meat thermo in my radiator after idling for ~20mins. showed 170 degree coolant temps, gauge was right at the middle. Does this sound right? If so, what is the coolant running when it nears the H side? What temp triggers the 'Temp' idiot light?

Read an earlier post where someone said they were running 160 or so and they were barely up off the C line, which made me wonder if maybe I'm not running as hot as it looks.

Yeller68 · 08-23-2006, 05:48 PM

I've been having some of the same issues myself. Temp gauge showing in the red, but I really don't think it's running hot. I'm going to try the meat thermometer myself, good idea.

BTW Raoul love your avatar. One of my fave movies of all time...

"Now, what's it gonna be young feller? You want I should freeze or get down on the ground? 'Cause if'n I freeze, I can't rightly drop. And if'n I drop, I'm gonna be in motion"

raoul.duke · 08-24-2006, 06:00 PM

ttt

Noone has any idea what the temp should be at the midpoint reading of a 'calibrated' C/H temp gauge? It's a '72, if that matters any....

**oldgold70c10** · 08-24-2006, 06:23 PM

Mine runs normally right in the middle, 180 degree thermostat, fairly new sender, gauge ground is good. I can always tell when my stat hasn't warmed up enough to open, because the guage will go towards the "H"; and then when the stat opens, it goes to the middle. Usuallt only does this when I have the heating water valve to the heater core in the off position. I would venture to guess that they were calibrated to run in the middle under normal conditions, etc.

powell72 · 08-24-2006, 10:45 PM

When my truck is at 180 it runs 1/4 of the way up, right where the red starts with my new gauge. The old one was 3/4 of the way up at 180, with everything else the same.

dwaite72lnghrn · 08-25-2006, 06:21 AM

I have the stock temp gauge in passenger head and aftermarket in the driver side. At 180* in aftermarket the stock is just at the left mark \\ on the stock. At 200* it is about a 1/4" above the left \\. At 230* it is at the right /red side. This was in the 402bbc. The 502bb is the same except I have never been to the red mark yet.

Fred T · 08-25-2006, 05:11 PM

Your's sounds like it's working right. 160-180 in the middle. The H side should be about 220.

08-23-2006, 04:32 PM	#1
raoul.duke Sandwich: Club Join Date: Mar 2006 Location: Houston, TX Posts: 119	Temp Gauge Position vs Actual Temps Been getting some high temp readings (to the first 'H' bar) out on the highway and have been reading the posts on bad sending units, which made me wonder- How do the gauge positions correlate to actual coolant temperature? Example- a meat thermo in my radiator after idling for ~20mins. showed 170 degree coolant temps, gauge was right at the middle. Does this sound right? If so, what is the coolant running when it nears the H side? What temp triggers the 'Temp' idiot light? Read an earlier post where someone said they were running 160 or so and they were barely up off the C line, which made me wonder if maybe I'm not running as hot as it looks. Last edited by raoul.duke; 08-23-2006 at 04:33 PM.

08-23-2006, 05:48 PM	#2
Yeller68 Active Member Join Date: Aug 2001 Location: Villa Rica, Ga Posts: 297	Re: Temp Gauge Position vs Actual Temps I've been having some of the same issues myself. Temp gauge showing in the red, but I really don't think it's running hot. I'm going to try the meat thermometer myself, good idea. BTW Raoul love your avatar. One of my fave movies of all time... "Now, what's it gonna be young feller? You want I should freeze or get down on the ground? 'Cause if'n I freeze, I can't rightly drop. And if'n I drop, I'm gonna be in motion"

08-24-2006, 06:00 PM	#3
raoul.duke Sandwich: Club Join Date: Mar 2006 Location: Houston, TX Posts: 119	Re: Temp Gauge Position vs Actual Temps ttt Noone has any idea what the temp should be at the midpoint reading of a 'calibrated' C/H temp gauge? It's a '72, if that matters any....

08-24-2006, 06:23 PM	#4
oldgold70c10 Who's got steelies? Join Date: Feb 2006 Location: Morrison, Oklahoma Posts: 1,026	Re: Temp Gauge Position vs Actual Temps Mine runs normally right in the middle, 180 degree thermostat, fairly new sender, gauge ground is good. I can always tell when my stat hasn't warmed up enough to open, because the guage will go towards the "H"; and then when the stat opens, it goes to the middle. Usuallt only does this when I have the heating water valve to the heater core in the off position. I would venture to guess that they were calibrated to run in the middle under normal conditions, etc. __________________ 1969 C10 LWB W/ 250 I6 & 3spd 1970 C10 with '67 small window cab, 68 front end, blue; 305/TH350, 3.08 limited slip rear end, manual brakes, power steering; & 4-wheel drums-My daily driver. 1975 Chevelle Malibu Classic Coupe 350/th350 mint green 1970 C20 Suburban 350/700R4 4.10 gearing green & white 1978 Big 10 Silverado 350/th350, working ac, 2 tone blue-My summer daily driver 1983 GMC 1500 Sierra 305/SM465 2.73 rear end How to add a trip odometer to your 67-72 stock speedometer How to rebuild your Q-Jet My Truck Page My Youtube Channel

08-24-2006, 10:45 PM	#5
powell72 Senior Member Join Date: Jan 2005 Location: Loveland Co. Posts: 3,098	Re: Temp Gauge Position vs Actual Temps When my truck is at 180 it runs 1/4 of the way up, right where the red starts with my new gauge. The old one was 3/4 of the way up at 180, with everything else the same. __________________ Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html

08-25-2006, 06:21 AM	#6
dwaite72lnghrn Registered User Join Date: Jun 2002 Location: central pa Posts: 1,525	Re: Temp Gauge Position vs Actual Temps I have the stock temp gauge in passenger head and aftermarket in the driver side. At 180* in aftermarket the stock is just at the left mark \\ on the stock. At 200* it is about a 1/4" above the left \\. At 230* it is at the right /red side. This was in the 402bbc. The 502bb is the same except I have never been to the red mark yet. __________________ 72 longhorn c30 502BB/th400/fact air/4.11rear/ custom camper 72 bug(the better half's) under reconstruction 2009 HHR aqua blue 71 GMC k20 350/sm465 2009 Chevy hd3500 6.6 Victory Red crew cab dually Dave & Jeanne Last edited by dwaite72lnghrn; 08-25-2006 at 06:22 AM.

08-25-2006, 05:11 PM	#7
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: Temp Gauge Position vs Actual Temps Your's sounds like it's working right. 160-180 in the middle. The H side should be about 220. __________________ Fred There is no such thing as too much cam...just not enough engine.



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