Hey guys,

I've been rebuilding my car for quite a while now. Some time ago, I bought a new water pump housing from another forum member because the old one I had broke. Unfortunately, it was long enough ago that I don't remember who I got it from. Anyway, recently I went to install it and discovered that there is a non-stock temp sensor where the stock temp sensor normally goes and the stock connector doesn't fit this non-stock sensor. Sooo...

1. Does anyone know what the resistance curve is for the stock thermosensor?
2. Does anyone know what the thread size is for the stock thermosensor? I think the 'other' sensor that is in this water pump housing is 3/8 NPT so maybe I can find an adapter.
3. Does anyone know what aftermarket sensors might be 3/8 NPT and what their resistance curve is?

Thanks for any help!

- Andy

 

Ok guys,

Well I figured out that the temp sensor that was in my water pump housing was a GM sensor, and it is indeed 3/8 NPT. I also discovered that the stock sensor is M12x1.5. Sooo...

1. Does anyone know the resistance curve of the GM sensor? I'm still searching. I did a quick experiment and suspended both the stock sensor and the GM one in some hot water and they had different resistances, so I don't think they're the same. Darn.

2. Does anyone know where I can find a male 3/8 NPT to female M12x1.5 adapter, or some combination of adapters that could get me there? I've been searching and can't find one anywhere.

- Andy

 

Alright, I think I found the GM sensor resistance table. Anyone have the Mazda one?

GM sensor table:
Degrees F:....Degrees C:....Resistance:
-40..............-40................100.7k
0.................-18................25k
20................-7.................13.5k
40.................4..................7.5k
70.................21................3.4k
100...............38................1.8k
160...............71................450
210...............99................185

This came from what I think is the megasquirt manual. http://www.megamanual.com/v22manual/mwire.htm


- Andy

 

Sorry to bring back an old thread, but this is exactly what I'm after, a table of the thermistor resistance for the stock coolant sensor. I plan on creating an LCD panel showing the thermistor value in degrees and it would be nice to reuse the wire that goes to the stock gauge.

 

Only thing I've ever seen are the values in the workshop manual

 

If you have the thermistor out of the car, making this curve requires only a stove, multimeter, and thermometer.

 

even bet that they are the same. plot the two on a graph. google thermister and use the one that is close.

 

Just to eliminate any confusion, the thermistor on the back of the water pump housing is for the ECU. The thermistor for the stock temperature gauge is on the rear iron under the oil filter.

The curve is typical, I plotted it once; I'll see if I can find it. I don't remember what the temp coefficient is, but it's relatively linear, iirc.