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Old 04-01-2010, 09:12 PM   #1
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Default 1.6 and 1.8 coolant temp sensors????

ok doing a reroute right now i have a 1.6 housing and i noticed the sensors are different sizes. the 1.8 is smaller diameter than the 1.6 sensor.

now my question is they are just two prong sensors there shouldn't be any difference in them besides size??? the radiator i'm using is a 1g dsm radiator they mount there temps sensor in the radiator which is the same size as the 1.6 temp sensor.

i'm thinking about switching to the 1.6 sensor and use it in this location. will there be any problems this way?
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Old 04-02-2010, 12:12 AM   #2
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Which sensor? On the 1.6 engine, there are three.

On the top of the thermostat housing, there's a single-terminal sensor that is actually just a thermoswitch. It controls the cooling fan, and the 1.8 engines don't have this.

Then there's a two-pin sensor installed in the rear water-outlet that feeds the heater core. This sensor feeds the ECU, and has the same thread as all of the 1.8 sensors, both the two-pin style in the '94-'97, and the three-pin style on the NBs.

Last, there's another single-terminal sensor screwed into the back of the head, just above the cursed water plug. This one drives the temp gauge in the dash, and is identical to the ones in the '94-'97 engines. NB engines don't have this sensor, as its function is integrated into the one in the water outlet (which is why, on the NBs, that sensor has three terminals instead of two.)

On the single-wire sensors, ground is through the threads. This is acceptable as these sensors are not doing anything terribly precise.

On the two-wire sensors, one of the wires is a ground. On the 1.6, this wire goes directly to ground through the harness. On the '94-'97, it goes to the ECU, and grounds internally in that.

In the NB three-wire sensor (which is two sensors in one) the sensor that feeds the dash gauge goes to ground through the threads, and the sensor that feeds the ECU has a ground wire that goes to the ECU, just like the '94-'97.
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Old 04-02-2010, 12:21 AM   #3
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The 1.6 one wont plug up to the 1.8 harness, or the 1.6 one i had wouldn't...
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Old 04-02-2010, 12:51 AM   #4
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Quote:
Originally Posted by Joe Perez View Post
Which sensor? On the 1.6 engine, there are three.

On the top of the thermostat housing, there's a single-terminal sensor that is actually just a thermoswitch. It controls the cooling fan, and the 1.8 engines don't have this.

Then there's a two-pin sensor installed in the rear water-outlet that feeds the heater core. This sensor feeds the ECU, and has the same thread as all of the 1.8 sensors, both the two-pin style in the '94-'97, and the three-pin style on the NBs.

Last, there's another single-terminal sensor screwed into the back of the head, just above the cursed water plug. This one drives the temp gauge in the dash, and is identical to the ones in the '94-'97 engines. NB engines don't have this sensor, as its function is integrated into the one in the water outlet (which is why, on the NBs, that sensor has three terminals instead of two.)

On the single-wire sensors, ground is through the threads. This is acceptable as these sensors are not doing anything terribly precise.

On the two-wire sensors, one of the wires is a ground. On the 1.6, this wire goes directly to ground through the harness. On the '94-'97, it goes to the ECU, and grounds internally in that.

In the NB three-wire sensor (which is two sensors in one) the sensor that feeds the dash gauge goes to ground through the threads, and the sensor that feeds the ECU has a ground wire that goes to the ECU, just like the '94-'97.
This partially answers a question I had about what do I do about the single terminal sensor that isn't on the 99 head? Should I just buy a the NB sensor and wire the third prong to the dash gauge? If so, anyone know where to source the three prong connector so that I can make a nice pnp connection.
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Old 04-02-2010, 12:54 AM   #5
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I honestly haven't a clue whether the electrical calibration is similar between the 1.6 and the NB sensors.

One option, if you have room, would be to pull the bolt on the back of the head near the outlet and install one of your sensors there.
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