Temp gauge failure
 

Randomly,on my 1985 gsl-se, the temp gauge stopped working. I was wondering if anyone has any suggestions on how to fix it. I'm guessing it's the sensor, but I don't know where it is located. Any help is appreciated! Thanks, Luke.

Temp sensor under the oil filter has failed.

I figured it out and bought a new one from Napa, but the one they gave me almost fits but it's too small. Does anyone know the part number?

There are actually two depending if the rear iron was a rebuild or not. I found this out the hard way. The only way to tell is by comparing your old one to a picture.

18-8569-510A - factory
18-G607-51X0 - rebuild

79-85 Engine Electrical

81-88 Rx7 Coolant Temperature Sensor (8569-18-510)

Thanks a lot!

One is bullet style and the other is spade style.

no, there are two bullet styles, and one spade

I went to Napa again but the employees there knew nothing about rotaries and basically told me I was wrong and looking for the wrong sensor. Both times I went there they were rude, so it looks like they lost another customer. I'm just going to buy one from mazdatrix now. Thanks for the help!

There are a few parts, like this one, that your only solution is to buy the factory part because nobody else makes them or the so-called aftermarket parts just don't fit or work.

Have you ever changed the harness connecter for the sensors? Like to use the 85 sensor in a 79? Are the values the same? Seems like Ive done this before, but its a little foggy. Maybe even a 86-91 sensor will work If the values are the same, but Ive been out of the FC game for too long... Cant remember.

I know i put my old 12a 80 sensor in my GSLSE 13b rear iron.

what would cause the coolant light to stay on even tho the coolant level is full on a 12a?

Bad coolant level sensor in the top of the rad. Whatever you do, don't over tighten it, there just made of plastic and leak very easy. Get a new one at rockauto.

thanks for the advice mate ill have a look into it.

there are two thread for the sensor, there is the 1968-1988 thread, and then 89+. the housings cast after a certain date, are ALL the late style thread. so there are three sensors.

1. bullet style with old thread
2. bullet style with NEW thread
3. spade style with new thread.

the spade style sensor has a slightly different range and will not give correct readings