jac1502

On my 81 I have three (what appear to be) temp sensors on the car. One dual wire located in the water neck next to where the emission stuff use to be, one single wire on towards the front driver side of the head, then a third on the rear passenger side head. I have A/C and a factory electric fan (don’t know if it works). I want to clean up my engine but I don’t know what goes to what, any help?

jac1502

someone has to know

Paul L

Passenger side is electric fan. Driver's side is temp gage. Are you sure the switch on the water neck is electric? Not vacuum hoses?

jac1502

No I took that stuff off with the smog pump. I think it was in my manifold before I switched to an edelbrock and the sensor was to tall to clear the radiator hose

Gator81

Paul is correct. Passenger side head sensor is for the electric fan, and is a 2-wire, if I remember right. Driver side head sensor is a one-wire for the gauge. Those two will physically interchange because the threaded holes in the heads are the same, but they operate completely different. The one for the fan is a thermal switch, with a single off/on point. The one for the gauge is a variable resistor.

The sensors in the water neck are not electrical, but are TVSs (thermal vacuum switches) for EGR and EFE operation. However, there is another electrical temperature sensor in the intake manifold near the water neck. The sensor provides intake temp data to the computer. [edit] Forgot to mention, the intake temp sensor for the computer is a two-wire.
:seeya


[Modified by Gator81, 12:36 PM 9/19/2003]

Paul L

Thanks for that clarification! The TVSs (EFE and EGR) were clear in my mind but I forgot the 1981 went to computer control; hence the wires to the t-stat area.

Big Fish

The one for the gauge is a variable resistor.

I'm glad this topic came up. I'm having a little problem with mine, does anyone know where I can get the ohms @ T degrees F?

Smokehouse69

I've never received a straight answer on this question, I'm still using my original sender (it still works thank goodness) but in the intake manifold, because my L98 heads (ZZ4 crate engine) only has 3/8npt holes in it for a skinny thermo-sensor. A while back someone posted a thread saying that they had found a Volvo sensor (I think the part number was WT508) that was a 3/8"npt direct replacement for C-3 sensors.
A couple of weeks ago someone else posted a link to a place that had direct replacement 1/2 npt sensors as a direct replacement, I went to the link, but they were sold out at the time.
I know that the ones you get from a parts house do not function as they should and aren't even close to what our gauges require.
I know one fellow who bought an aftermarket gauge and installed it under his hood, that way he could "adjust" his dash gauge by eye.