Which sensor is it?

[Butterfinger]

Correct me if I'm wrong, in the photo, the yellow-circled sensor is the manifold pressure sensor, and the red-circled sensor is a water temp sensor.

How many water temp sensors are there (there's another one on the return line from the heater core)?

 

[ID89GT]

The yellow circled one is the air temp sensor.. it measures the temperature of the incoming air. And yes the other sensor is the coolant temp sending unit for the gauge. The ECM temp sending unit is on the black heater pipes on the other side of the intake that go to the heater core. It threads directly into the pipe.

 

[Butterfinger]

Thanks. I wonder why they used a different sensor for the gauge and the ECM.

 

[VibrantRedGT]

Just bought both on Friday. The one closest to the front of the intake is for the water temp gauge. The white one is the temp sensor. It cost me $29 for that one and $7 for the brass gauge one.

 

[Butterfinger]

So in order to add a water temp gauge while keeping the factory gauge functional, would a T-fitting be required (like with the oil pressure)? Is there enough room under the upper manifold to make it work?

 

[ID89GT]

You could use one of the rear boss spots on the lower intake. Either drill the one on the driver side or use the egr coolant tube spot on the passenger side. Another option is to go into the top of the t stat housing. Or like mentioned used a t port in one of the coolant hoses somewhere.

 

[HISSIN50]

But you cannot use a Tee fitting with two senders in the same Tee. This results in an alcove of coolant that does not reflect actual temps. The probes need to be in the flow of coolant.

I agree with putting the stock sender in the rear or t-stat housing. A housing with a 3/8" NPT boss is under 15 bucks at the parts store. Of course, if your stat sticks closed, the sender in the housing will not reflect accurate temps (you're not going to use the stock gauge much anymore anyhow).

 

[jrichker]

Alternate placement for a temp gauge sender: Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.

Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.

 

[Butterfinger]

But you cannot use a Tee fitting with two senders in the same Tee. This results in an alcove of coolant that does not reflect actual temps. The probes need to be in the flow of coolant.

Good point, I didn't think of that.

jrichker: Thanks for the details