EastSidinA4

I have an 88 FC Turbo II and I see several water temp/thermo switch/sensors throughout the system. Can someone tell me what each one of them does? The two by the thermostat, the one under the radiator, (is there one near the oil filter?), are there others Im missing?

The reason why am asking is because my stock temperature gauge on my cluster doesnt work. Also, I have an after market aluminum radiator that does not allow the sensor to screw into the bottom of the radiator. It is a sensor with two contacts at the bottom of the radiator that is just hanging.

unek87

well i know that the temp sensor on the water pump housing is for the ecu . the one on the driverside of the engine is for the temp gauge i believe and if you have one on the filler neck that goes to the electric fan for the ac . i could be wrong though

satch

iTrader: (1)

The one on the lower part of the stock radiator, driver's side, is for the 3000 rpm start up which really isn't necessary. Of all the temp related sensors it is the least important.

The two plugs that run to it each has a single wire. If the two wires are jumpered then the 3000 rpm start up will engage when turning on the car while if you leave them unjumpered it won't go through the 3000 rpm rev upon start up.

EastSidinA4

So the one on the bottom of the radiator, can I just disconnect it and jump the wires together?

Where exactly is the one for the temp gauge on the drivers side? I believe that is the culprit for my broken meter. I tried looking but I cant find it. Any pictures would be helpful.

Thanks guys.

satch

iTrader: (1)

If you want the 3000 rpm rev upon start up to occur each and every time you start the car then yes.

Locate the oil sending unit, located under the oil pedestal, as it looks similar to a mushroom and the temp sensor you are looking for is located nearby and has a single Yellow/White wire connected to it.

clokker

iTrader: (2)

To find the water temp sending unit:
_Find the oil filter, look just below and forward to see the large oil pressure sending unit (it will have a single wire connected to the top and is commonly referred to as "mushroom shaped" although I can't imagine why...).

_Note that the oil pressure sending unit is raised off the block by a spacer (this $.50 spacer is why the FC sending unit costs twice what a comparable sender sans spacer goes for)

_The reason for the spacer is the water temp sending unit which is almost underneath the oil pressure unit.
It's a smaller part, threaded into the block and once again, features a single wire connector.

EastSidinA4

Sorry for sounding like a newb. I'm not new to forums but I am to rotaries. I've tried searching dozens of threads but they all refer to where to put an aftermarket sensor.

Here is a pic of my oil filter area, is it the left arrow or the right arrow underneath the oil pressure sending unit?

RotaryEvolution

iTrader: (30)

left arrow, looks like a bullet head when you remove the connector.

EastSidinA4

So left arrow is the sensor for the temp gauge? Any other reason why the temp gauge wouldnt work? Sensor, wiring, gauge? Is there a fuse?

satch

iTrader: (1)

Yes, the left arrow is the sensor you asked about.

RotaryEvolution

iTrader: (30)

the meter fuse in the cabin powers the gauges but none of them would work if it is blown.

EastSidinA4

Thank you for all your help. It must be a bad sensor because it's connected fine at the sensor. Anyway to test it out? By grounding it to the chassis maybe?

satch

iTrader: (1)

If you removed the sensor and stuck the end that is curently in the engine and place that end into water with a temperature of 176 degrees and used a multimeter set to ohms it should read 49 to 58 ohms.

EastSidinA4

Ok, so remove it completely from the engine/wiring and stick it into a pot of hot water with a multimeter. Thanks!

RotaryEvolution

iTrader: (30)

best place to start is to check the gauge and wiring first, turn the key on and run a jumper fire from the open end of the coolant temp sender connector to ground, the gauge should peg hot. if it does then you have a bad sender, if it doesn't then you have an issue between the sender and the gauge or inside the gauge itself.

satch

iTrader: (1)

Karack's idea is easier and better.

EastSidinA4

Thanks, thats what I figured. Grounding out the wire to see if the gauge moves up.