Temp Sender??

[karl]

1977 C10 350/350. I have an aftermarket temp gauge and am trying to get the stock electric one working. I want to run a sender off the top of the intake but not sure which sender to use? Anyone know the part number? Im afraid of running wire close to my header. Probably the reason so many dont work. Thanks.

[ray_mcavoy]

The stock temperature gauges from 73 to 78 originally used a GM #1513321 sending unit. It has 1/2" NPT threads.

Replacements are available from most auto parts stores (Standard Motor Products TS-6, Wells TU5, or equivalent). American Autowire (http://www.americanautowire.com) and Lectric Limited (http://www.lectriclimited.com) both sell sending units as well. They claim they have a temp. vs. Ohms curve that is closer to the original GM specs than other replacement sending units.

Also be aware that GM changed to a different sending unit & gauge sometime in 1979. They have a different temperature vs. Ohms curve than the earlier years. The 78 & older gauges will read too low if used with one of these newer type sending units.

[79azc10]

I have a 79 , do you know what the correct part number for
The temp sender, I replace mine with one from autozone and it ain't working right. I grounded the plug and the gauge pegged, but the sensor still won't read right.

[ray_mcavoy]

Originally Posted by 79azc10

I have a 79 , do you know what the correct part number for
The temp sender.

There are 2 sending units listed for 79.

One is GM #8993106. It has 1/2" NPT threads. The currently available AC Delco replacement is #2134792. Standard Motor Products equivalent is TS-71 and Wells is 1T1049.

The other is GM #8993146. It has smaller 3/8" NPT threads needed to fit some engines. And I think this one might still be available from GM. The Standard Motor Products equivalent is TS-76 and Wells is 1T1008.

1979 was the changeover year so there might have been some trucks built early in that model year that were still using the 78 & older type gauge & sending unit. And unless you know the complete history of the truck, it's possible that someone swapped in an older temp gauge since they're physically interchangeable.

Originally Posted by 79azc10

I replace mine with one from autozone and it ain't working right. I grounded the plug and the gauge pegged, but the sensor still won't read right.

The fact that the gauge pegged when you grounded the sending unit plug is a good sign ... that means the gauge & wiring are most likely okay.

You can do some more testing by temporarily substituting some resistors or a potientiometer (variable resistor) in place of the sending unit. Connect one end to the sending unit wire/plug and the other to ground.

With the 79-up gauges, a resistance of about 100 to 110 Ohms should make the gauge read mid-scale. And a resistance of about 55 to 60 Ohms should give a full hot (but not pegged beyond) reading.

With the 73-78 gauges, a resistance of about 65 to 70 ohms will give a mid-scale reading and about 45 to 50 ohms will give a full hot (but not pegged) reading.

[79azc10]

Thanks

[karl]

My intake manifold will only take a 3/8 NPT or smaller sender. The hole is too small for the 1/2 NPT sender. I am running electic so i dont want to run wires next to my headers if i can help it. Any suggestions?

[ray_mcavoy]

Originally Posted by karl

My intake manifold will only take a 3/8 NPT or smaller sender. The hole is too small for the 1/2 NPT sender. I am running electic so i dont want to run wires next to my headers if i can help it. Any suggestions?

One option would be to swap to a 79 or newer temperature gauge and use a GM #8993146, Standard TS-76 or Wells 1T1008 sending unit. Those have 3/8" NPT threads.

Most of the later year temperature gauges will have some cosmetic differences though ... like a little thermometer symbol instead of the word "TEMP" and a lighter orange colored plastic needle instead of the darker orange painted aluminum needle. If having it match the rest of the gauges is important, there was a 79-only temp gauge (GM #8993329) that might work if you can find one. It has the same styling as the 78 & older gauges. And I'm not 100% certain, but I think it is electrically compatible with the newer type sending units such as the #8993146.

Another option would be to keep your existing 77 gauge and try a Standard #TS-131 or equivalent sending unit. Those have small 1/8" NPT threads so they can be adapted to most holes with a reducer bushing. It's meant for Chrysler applications but the temp/resistance values are similar to the original GM #1513321. It's not an exact match though so the gauge might be a little off. Lectric Limited has a good write-up showing how you can add resistors to help compensate for a sending unit that isn't a perfect match for the gauge --> http://www.lectriclimited.com/freque...stions.htm#E02

[karl]

Thanks. Can i put the 1/2 NPT sender in the water neck hole above the thermostat or is that a problem?

[donut]

You can, however, true coolant temp won't be measured until after the thermostat opens.
When I was running 2 gauges, I had one in the intake, 1 in the water neck. Primary in the intake.

Basically, you can put the sender in any coolant port.

[79azc10]

Sorry to bring this up again. Should I be using pipe tape on the sensor or leave it off

[hatzie]

Don't use pipe tape. The sender grounds through the threads.

[79azc10]

Ok thanks

[Just1more]

Is there a reason you want to put the sending unit in the intake? All three of my squares have it in the driver's side head. I'd be concerned about putting it in the water neck, if the thermostat failed to open, it would take a long time for an overheating condition to show up on the gauge, if it ever did.

[jocko]

You need member Brian Mac. The correct temp sender for your gauge, not your engine needs to be used. If it is too large for the head, Brian Mac does a masterful job of turning down the threads to the correct size on the correct sender to fit the later year heads. Sends correct signal to make your gauge read correctly and fits the new head. I have received a few from him, all work and seal perfectly. Recommend pm him - great guy! http://67-72chevytrucks.com/vboard/s...d.php?t=342203

[hatzie]

Some aftermarket intakes have sensor bosses in the coolant crossover under the thermostat. The cylinder head is still the best location.