I have just replaced the stock heads on my '74 L48. The original heads used temperature sensors with 1/2" threads. There is one on each side. The driver's side has a single spade-type connector, the passenger side sensor has two spades.

My new heads have 3/8" plugs for the sensors, so I need to get new ones. I have several questions....

1. Why are there two temperature sensors in the first place? The car only has one temperature guage and no idiot light for temp.

2. I went through NAPA's catalog and out of hundreds of temperature sensors I was able to find one with 3/8" threads that has a single spade (it was listed for Chevrolet, 1976-1980). I bought two of them because there were NO 3/8" dual-spade sensors at all. Can I make a single-spade sensor work in place of the dual-spade unit?

3. Why are the two sensors different, anyway?

4. Has anyone else run into this, and can you reccomend parts?

5. Could this be any more frustrating?

Thanks!

 

If you have an electric fan, then one is to ground the fan (or it's relay).

For your guage, you want an '82 vette unit WT359 "Temperature Sending With Gauge", about $10.

 

Thanks!

 

What are the ohms @ 220° for that WT359? Seems they are double according to specs I found.

WT359 3/8" NPT (TS6641 - NAPA) = 138-156 Ohms @ 220°
TS6469 1/2" NPT = 72-78 Ohms @ 220° (stock single spade)

Would think the gauge would be way off.

 

I think Lectric Limited has the sensors with the correct resistance range. Checkout their site at http://www.lectriclimited.com/mainpage.htm



A New Solution To An Old Problem!
Is your car running too hot?
Maybe your temperature gauge is not telling you the truth.
Most cars have had their temperature sending unit replaced with a GM/Delco or an
auto part's store replacement temperature sending unit. This may be your problem!



Lectric Limited now offers accurate temperature sending units for many Chevrolet, Buick, Oldsmobile, Pontiac & Cadillac vehicles. Months of research were devoted to this project in order to provide our customers with sending units that have the original-type terminal connection, housing and resistance (thermistor); resulting in an accurate gauge reading. They screw right into the 1/2" pipe thread hole (as original).

Both auto part's stores and GM/Delco do sell replacement temperature sending unit, but they do not produce an accurate gauge reading in vintage cars. This is because sending units from an auto part's store and even GM, are only a generic replacement; often requiring a new, matching gauge or re-calibration of your original gauge.

Please Note: The terminal connections on all our sending units are as-original
Through the years, the mating terminal & connector on your harness may have been
changed by you or a previous owner. This change was most likely made in order to try
different sending units when the "exact replacement" unit didn't work or was not available.
If your harness had been modified from original, we do offer replacement
Temperature Sending Unit Lead Repair Kits. (See our “Repair Components” section.)

Consult our on-line catalog & order form for your application & price.
Made in U.S.A.

 

i'm using a holley temp sending unit that i got from summit. it seems to work pretty well.

http://store.summitracing.com/partde...5&autoview=sku

 

Thanks. If the sensor I got from NAPA doesn't work (I expect it will not), I'll check out those options.

The wiring diagram in the shop manual only shows the sensor on the driver's side, with nothing on the passenger's side. Could be Bubba's handiwork. So, I've capped the passenger's side off.

 

Seems extra sender has something to do with emissions/TCC on carb.

AFAIK ... LL does not offer a sender that's both correct ohm for 74 gage and has 3/8" pipe thread.

If you changed heads ... maybe you changed intake too.
If so, you're probably in luck.
Most aftermarket intakes have a spare hole with 1/2" pipe thread ... put the OE sender there.

 

On my 80 L82 there are two temp sensors. I believe the drivers side sensor is for the gauge and the sensor on the passenger side is for the auxilary electric fan. Semper Fi.

Bob

 

for a 74, this is correct (pass side)
diriver side is for temp gauge

 

Hmmm...my carb is the original and has no electrical connectors. Not even an electric choke.

 

need a vacuum/electrical diagram . . . if memory serves, i think that sensor essentially blocked vacuum to the distributor

 

Yeah, I have a complete diagram in the shop manual and it doesn't show anything on the right side of the engine...maybe its a 1975+ thing? At any rate, I don't want the vacuum advance to be interfered with by smog crap so I won;t shed any tears for it.

 

that sensor was actually there at one time on my 74; it shows up labelled in the wiring diagram as something like: "vac adv sol". seems like it was meant to block the vacuum signal to dist until water temp got hot enough thereby saving our lungs, the earth, and all . . .

i agree with you, if no ncrs, no need,
just clean up wiring on pass side

 

That's what I'm referring to ... both my 71 had em ... kind of a vac break solenoid affair bolted to driver side of carb ... to interact w/ driver side throttle arm ... wired to pass side head sender. Can be easily removed/refitted. I still have mine; stowed away.

 

I need some help with my new 73. The temp gauge does not work, and I have these two sensors, but neither is hooked up to anything. The one on the driver's side has 2 connectors on it. The one on the passenger side has one.

There is a brown wire that comes out of the harness near the vacuum line to the light switch. It is long enough to reach the one on the driver's side, but I think it is supposed to hook to a solenoid on the carburator. The carb is a replacement one, and there is no solenoid on it.

There is a green wire that comes out of the harness near the alternator that reaches this sensor.

I hooked up both of them and the sensor pegged, so I disconnected them. I hooked up the green one, but the gage never went above 100.

I can not find a wire on the passenger side.

Can anybody tell me what color wire hooks to which sensor, and which wire goes to the temp gage?

I got the fuel gauge working, by connecting the wire on the sending unit.

My ammeter gauge does not work, either.

 

Curby, the green wire is for the temp sensor.
The sending unit should only have one lead on it
If your not reading more than 100* then either the sending unit or the gauge are faulty or you have an incorrect sending unit.(my guess)
Ignore the sending unit on the pass side, you don't want it hooked up as stated above.

 

Hi, the temp sending unit on my 74 is on the left front, it has one wire,
on the right is the TCS sender (Page 6-6 in Haynes).
The ohms have to be correct or the guage will be off.
Hope this helps, Pete.

 

The one on pass side is the tcs (transmission controlled spark). It is just a temperature controlled switch. The TCS system would block vacuum advance to the distributer depending on engine temp and what gear the transmission was in. It was an emission control item, most have been disconnected long ago.

Greg

 

But, if you want to run an electric fan, the passenger side is the one that you would use. You can buy switches that operate at different temps to turn the fan on (like 200 as a high heat eliminator)