Hello,

86 N/A base 4 lug S4

My question is about water sensors.. . .I am replacing them in an effort to get this back on the road..

My first question is what sensor do I get for the bottom radiator. It is a aluminum radiator, has a 1/4" NPT fitting, and it looks to be the two prong version. see pic below on lower radiator. . . .. Do I use any temp sensor that meets the bill and has two prongs?

. . . . My next question is this: . . .I have a clutch driven fan. But I have three water sending units. How does the engine ECU handle those inputs? It's pretty obvious about the low level on the top of the radiator but what's the control difference between the other two.

• The low level alarm on the top of the radiator 8553-15-610B
• The 2 prong sensor on the bottom of the radiator . . ( I'll call it Standard STDTX18 for now cause that one looks to fit)
• The 1 prong thermistor on the side of the engine under the oil filter. 8569-18-510A
• 
  
  Aluminum radiator bottom water temp sensor, two prong
• 

Picture showing upper radiator cap. and bleed off port on upper elbow of aluminum radiator. .. .Notice overflow vent tube crossing over heading to stock location of overfill/vent catchpot


Photo of Engine block water temp sensor. Pt # 8569-18-510A single prong with crush washer thermistor


Showing location of vent tube exiting the aluminum radiator heading around to the vent catch pot. . . .. Low level sensor on top of radiator



If you look closely, you can see the two radiator caps. The upper one is right under the strut tower bar. . . .The upper radiator cap has no vent tube connection. . .. The lower radiator has the vent tube.

 

so yes, there are 4 sensors, its an old computer system...
low coolant, like you say
the one by the oil filter is for the gauge
the one in the radiator, FE85-18-840 it switches at 65c, and basically turns on closed loop

the 4th is the coolant temp sensor for the computer, its in the back of the water pump, Green 2 pin; 8574-18-840
and if you have a turbo or automatic, there is a fan switch on the thermostat housing, B303-18-840

 

Nice thanks.

One more question if you have the time.

I assume the bottom radiator switch tells the "system" when to turn off the AWS system, ? . . .I seem to recall 65 C as the trip point.

While the important one is what you said, , , ,The one behind the radiator probably is the one that tells the ECU how to handle the lean/rich fuel mixture.

Took some time to find it . . . .Underneath the alternator on the back side.

Which I will replace with the NGK/NTK Coolant Temp Sensor EF0090 (73949).

Might as well do all of them at once. Gotta take the upper and lower intake off to get to the EGR and injectors.. . . .She's gonna get an overhaul and hopefully make it back on the road someday,. . . . .Water system is part of the process.

Thanks,

 

65c sounds right to me too. it does something with closed loop too, but i think it would turn the AWS off also