Temp gauge not moving much - The 1947 - Present Chevrolet & GMC Truck Message Board Network

76JimmyBlue · 12-02-2023, 10:02 PM

The temp gauge on my '76 has never really moved past cold, even after driving for long periods of time. Actually the one time it got close to middle of the gauge was when it has a leak in the radiator haha. Havin trouble testing the sender but when I ground out the wire the gauge pegs all the way hot. Which I believe means the gauge works. The other option is if the thermostat is getting stuck or pushed open. It has an original "AC" 195 degree ( if I remember right) thermostat which I tried testing in hot water and seemed to open up fine. The upper rad hose immediately pressurizes on a cold start up like the rad isn't being bypassed by a closed t-stat. Also where on the gauge should the needle point/ what's the normal operating temp once warmed up? SBC 400 engine.

Pontiac1976 · 12-17-2023, 10:52 AM

around about 195-210 depending on your cooling options if towing at warm to hot day warmed up temp.

Wikid61 · 12-17-2023, 11:26 AM

Quote:

Originally Posted by 76JimmyBlue

The temp gauge on my '76 has never really moved past cold, even after driving for long periods of time. Actually the one time it got close to middle of the gauge was when it has a leak in the radiator haha. Havin trouble testing the sender but when I ground out the wire the gauge pegs all the way hot. Which I believe means the gauge works. The other option is if the thermostat is getting stuck or pushed open. It has an original "AC" 195 degree ( if I remember right) thermostat which I tried testing in hot water and seemed to open up fine. The upper rad hose immediately pressurizes on a cold start up like the rad isn't being bypassed by a closed t-stat. Also where on the gauge should the needle point/ what's the normal operating temp once warmed up? SBC 400 engine.

Drain the coolant. Run if for a bit.

**hatzie** · 12-18-2023, 10:36 PM

1976 has the old GM 0513321 nailhead temp sensor.
Most aftermarket and even AC Delco replacement sensors do not have the same thermistor resistance curve as the originals.
If it's had the sensor replaced the gauge will not work properly.

Ecklers sells one that's supposed to work properly. https://www.ecklerscorvette.com/1957...-129200-1.html

**mr48chev** · 01-02-2024, 12:02 AM

I had that same issue with my 77 and went with a Delco G1852 sender. I think I ordered it from Amazon though. I looked it up to make sure and dang, that has been a while. The gauge works right per my heat gun though

I wouldn't trust an old thermostat and would replace it with a new quality brand one.

truckin 79 · 01-02-2024, 08:57 AM

I had the same issue and someone put a temp sender for a light and not a gauge. I will say if you have a four core radiator the temp goes about a 1/4 of the way on the gauge but have never seen it go half. I have not towed with the truck though so who knows what temp is then

cadillac_al · 01-02-2024, 04:44 PM

All my trucks go up to about quarter way. If I ever see it half way in the middle I know there is a problem.

**Accelo** · 01-02-2024, 06:32 PM

All the aftermarket stuff is junk as far as accuracy goes.

Do not use any tape on the threads when installing.
After installation, I checked resistance between the manifold and the sender outer housing, and it should be essentially zero.

You can still sometimes purchase an AC part new. You can often find NOS ones on Ebay... Avoid the "made in Mexico" ones as the quality suffered when the production was changed.

One of these cheap sensors caused me a lot of headaches before I knew they were all over the map as far as resistance goes.

In my case, I checked everything and ended up replacing the water pump. Which was not the issue but it caused a big one when the casting broke with less than 50 miles on the newly rebuilt pump.
The fan went into the radiator, took out my radiator, fan clutch and fan. My assumption was the prior owner ran the pump to failure and then the re builder was too cheap to check it for cracks.
Later I traced it down to the (Piece of S) sensor. Last rebuild water pump I ever purchased.

Consumers are now the quality control department.
Probably best check is in boiling water (212 F) with a ohm reading of 78 ohms +/- 2.
Most stock gauges when inputted with 79-82 Ohms will read right around 212. This is a general statement regarding GM temp gauges. May or may not be applicable to our C10's but it's correct for the general time period.

BTW the Amazon ACDelco part says "Professional, premium aftermarket replacement".
It also says this: "Temperature Low-100 Degree F inch. Temperature High- 220 Degree F". Exactly what does that mean? No resistance at a specific temp given.
Some guys have been know to purchase three of the sensors and then use the one "closest" and return the others.
Says a lot when they vary a lot even between the same manufacture.
I never trust Amazon till I read all the fine print.

A friend of mine manufactures coffee pots. He has to trace this stuff down all the time. One time even the quality control dept measuring device was off.

Cheers.

**Willowrun** · 01-03-2024, 12:03 AM

Quote:

Originally Posted by cadillac_al

All my trucks go up to about quarter way. If I ever see it half way in the middle I know there is a problem.

Same here.

76JimmyBlue · 02-24-2024, 08:09 PM

It does have the big four row radiator. I have to check again but I don't think it's even coming close to 1/4 up the gauge when warmed up. When testing the resistance, do I put one tester lead to the sender body or the block? I was having a hard time getting any reading. If i really have to I guess I'll replace that sensor, probably maybe the one hatzie suggested, and the thermostat because I think it's original to the truck.

Axle · 03-02-2024, 09:04 AM

If you don't have one, buy yourself an infrared temp gun. It'll at least give you a ballpark of temps to see how close or far off the guage is.

I gave up on temp sensors for my 81, stuck an aftermarket guage in it, at least I get temperatures that are reasonably accurate.

76JimmyBlue · 04-22-2024, 12:25 AM

Quote:

Originally Posted by Axle

If you don't have one, buy yourself an infrared temp gun. It'll at least give you a ballpark of temps to see how close or far off the guage is.

I gave up on temp sensors for my 81, stuck an aftermarket guage in it, at least I get temperatures that are reasonably accurate.

I have one I can borrow. What temp am I looking for, and do I aim it at the sender?

12-02-2023, 10:02 PM	#1
76JimmyBlue Registered User Join Date: Jun 2022 Location: Bothell, Washington Posts: 25	Temp gauge not moving much The temp gauge on my '76 has never really moved past cold, even after driving for long periods of time. Actually the one time it got close to middle of the gauge was when it has a leak in the radiator haha. Havin trouble testing the sender but when I ground out the wire the gauge pegs all the way hot. Which I believe means the gauge works. The other option is if the thermostat is getting stuck or pushed open. It has an original "AC" 195 degree ( if I remember right) thermostat which I tried testing in hot water and seemed to open up fine. The upper rad hose immediately pressurizes on a cold start up like the rad isn't being bypassed by a closed t-stat. Also where on the gauge should the needle point/ what's the normal operating temp once warmed up? SBC 400 engine.

12-17-2023, 10:52 AM	#2
Pontiac1976 Registered User Join Date: Oct 2015 Location: Ottawa, Ontario, Canada Posts: 766	Re: Temp gauge not moving much around about 195-210 depending on your cooling options if towing at warm to hot day warmed up temp. __________________ 1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.

12-18-2023, 10:36 PM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Temp gauge not moving much 1976 has the old GM 0513321 nailhead temp sensor. Most aftermarket and even AC Delco replacement sensors do not have the same thermistor resistance curve as the originals. If it's had the sensor replaced the gauge will not work properly. Ecklers sells one that's supposed to work properly. https://www.ecklerscorvette.com/1957...-129200-1.html __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

01-02-2024, 12:02 AM	#5
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,711	Re: Temp gauge not moving much I had that same issue with my 77 and went with a Delco G1852 sender. I think I ordered it from Amazon though. I looked it up to make sure and dang, that has been a while. The gauge works right per my heat gun though I wouldn't trust an old thermostat and would replace it with a new quality brand one. Attached Images __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around. Last edited by mr48chev; 01-02-2024 at 12:20 AM.

01-02-2024, 08:57 AM	#6
truckin 79 Registered User Join Date: Jun 2014 Location: CO Posts: 749	Re: Temp gauge not moving much I had the same issue and someone put a temp sender for a light and not a gauge. I will say if you have a four core radiator the temp goes about a 1/4 of the way on the gauge but have never seen it go half. I have not towed with the truck though so who knows what temp is then __________________ 79 Chevy 2wd BIG10 350 TH400

01-02-2024, 04:44 PM	#7
cadillac_al Registered User Join Date: Oct 2013 Location: Maine Posts: 2,376	Re: Temp gauge not moving much All my trucks go up to about quarter way. If I ever see it half way in the middle I know there is a problem. __________________ 76 Chevy K20 76 GMC K15 77 Chevy C10 77 Chevy K10

01-02-2024, 06:32 PM	#8
Accelo Senior Member Join Date: Mar 2015 Location: washington Posts: 2,296	Re: Temp gauge not moving much All the aftermarket stuff is junk as far as accuracy goes. Do not use any tape on the threads when installing. After installation, I checked resistance between the manifold and the sender outer housing, and it should be essentially zero. You can still sometimes purchase an AC part new. You can often find NOS ones on Ebay... Avoid the "made in Mexico" ones as the quality suffered when the production was changed. One of these cheap sensors caused me a lot of headaches before I knew they were all over the map as far as resistance goes. In my case, I checked everything and ended up replacing the water pump. Which was not the issue but it caused a big one when the casting broke with less than 50 miles on the newly rebuilt pump. The fan went into the radiator, took out my radiator, fan clutch and fan. My assumption was the prior owner ran the pump to failure and then the re builder was too cheap to check it for cracks. Later I traced it down to the (Piece of S) sensor. Last rebuild water pump I ever purchased. Consumers are now the quality control department. Probably best check is in boiling water (212 F) with a ohm reading of 78 ohms +/- 2. Most stock gauges when inputted with 79-82 Ohms will read right around 212. This is a general statement regarding GM temp gauges. May or may not be applicable to our C10's but it's correct for the general time period. BTW the Amazon ACDelco part says "Professional, premium aftermarket replacement". It also says this: "Temperature Low-100 Degree F inch. Temperature High- 220 Degree F". Exactly what does that mean? No resistance at a specific temp given. Some guys have been know to purchase three of the sensors and then use the one "closest" and return the others. Says a lot when they vary a lot even between the same manufacture. I never trust Amazon till I read all the fine print. A friend of mine manufactures coffee pots. He has to trace this stuff down all the time. One time even the quality control dept measuring device was off. Cheers. Last edited by Accelo; 01-03-2024 at 03:15 AM.

02-24-2024, 08:09 PM	#10
76JimmyBlue Registered User Join Date: Jun 2022 Location: Bothell, Washington Posts: 25	Re: Temp gauge not moving much It does have the big four row radiator. I have to check again but I don't think it's even coming close to 1/4 up the gauge when warmed up. When testing the resistance, do I put one tester lead to the sender body or the block? I was having a hard time getting any reading. If i really have to I guess I'll replace that sensor, probably maybe the one hatzie suggested, and the thermostat because I think it's original to the truck.

03-02-2024, 09:04 AM	#11
Axle Registered User Join Date: Jul 2011 Location: SW Ontario Posts: 1,212	Re: Temp gauge not moving much If you don't have one, buy yourself an infrared temp gun. It'll at least give you a ballpark of temps to see how close or far off the guage is. I gave up on temp sensors for my 81, stuck an aftermarket guage in it, at least I get temperatures that are reasonably accurate.



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