I'm using '88 housings for my '89 rebuild. Everything works except for the water temperature sensor. It looks totally different than the one on the '89. The problem is that the '89 has a larger thread than the '88 sensor. The sensor is located on the rear side housing under the oil filter. I measured the resistance and the '88 sensor has around 900 ohms and the '89 has like around 600 ohms (maybe the other way). Is this for the gauge or is it for the ECU?



I'm hoping it's just for the gauge so i can neglet it w/o having to tapo a different thread.



Thanks,





Robert

Thats the oil pressure gauge sender, the water temp sender for the ecu is on the waterpump assembly

http://www.mazdatrix.com/pictures/o-elect/o3-1.jpg



you're talking about that sensor correct?



Note: A few years ago MAZDA changed the thread on the water temp sender in the rear side housing from the straight thread that they had used forever, to a metric pipe thread. All NEW rear housings have the new thread. It is essentially impossible to tell which you have with out looking at it. Most cars still use the straight thread. However, if the engine has been replaced with a FACTORY rebuilt, there is a small chance you have the pipe thread. The new sender will not read correctly in pre-80 cars



from mazdatrix's website.



and yes it's the water temp sensor.

The thread pattern for the up to 88 is the 1/8 npt. The 89 and up are 10mm x 1k. 10 mm will fit loose in the 1/8npt. you can get a 1/8npt tap from a hardward store and change the threads on the housing.

Yeah those are the sensors. The one on the right or middle is the one on the '88 housing and the one on the left is on the '89 housing. I'm using the '88 housings but need the '89 sensor.

Is it for the ECU or for the gauge? If it's for the gauge then i won't bother changing it cause i have an aftermarket water temp gauge but if the ECU needs it then I'll have to retap it.

It's the gauge sender, the ecu's water temp sensor is behind the waterpump assembly

Alright, thank's a lot!!! Much appreciated.

The guage is crap anyways. use the 89 sender to keep it form leaking coolant.



Get an aftermarket guage and tap into the water pump housing https://www.nopistons.com/forums/pub...IR#>/smile.png