The wire on my coolant sensor finally gave up the ghost recently so instead of ordering one from Mazda for 70 bucks, I thought I could dig into the little bugger and see if I could pick up the wire. Anyway I fixed it so here goes the writeup.


Tools
-17mm open ended wrench
-wire stripper/ crimper
-Soldering iron
-Solder
-Dremel with assorted bits
-High Temp 2 part black adhesive

Supplies
-Small ring terminal
-Wire
-Heat shrink tubing
-Wire Connector
-Pen spring

First, obviously remove the sensor with a 17mm wrench from the radiator, be gentle, its plastic.

Take your dremel out and remove all of the gray epoxy until you see this:


This is the meat of the problem. This is where the wire attaches to the metal rod in the middle. There is a little copper or brass plate there that is what I soldered to.
Get your ring connector out and crimp some wire to it, either the original wire (it was brittle on mine) or some newer wire. Make sure if you have a ring connector with a plastic insulator to cut the plastic off, all you want is the metal.


Take a length of solder wire and wrap it around the metal rod in the middle so it acts like a washer. Put the ring conector on the rod above the solder. Place the iron on top of the ring and heat the whole ring up until the solder melts under the ring connector.

Notice how the wire sticks out the side instead of going up. this will prevent future wire stress.

Find your self a good quality high temp adhesive. I used 3m 08223 mix and neatly apply to the interior of the sensor. Take your pen spring and slip it over the wire for further protection from stress fracturing. I added a rubber cap over everything to make it look a little more factory, not necessary, but it looks better now.

Get out some and heat shrink tubing and cover the whole wire to make it look clean.

End result




Took about 2 hours with interruptions. Probably would take 30min next time.

 

whats coiled around the end of the wire there?

 

it's a pen spring to help aid the wire from being bent and breaking prematurely, step seems to be missing but is also probably optional as i can't see it aiding the stress point all that much.

nice writeup nonetheless, i have a few i planned on doing similar repairs on and it's good to see what to expect.

mazda's price on this part is rediculous, albeit it should only be about $40 from the dealer so yours has a steep markup...

 

The spring actually does help quite a bit. If I was to do it again I would get a stainless spring from ace or something. But the step is in there, its just hiding.

Last-ish step.

 

I just ordered one from Autozone for $22.

 

Ya,but can you WRITE with it?

 

I'd say we should get an archive on this
The middle part of the wire is just solder right? No added resistor or anything?

 

Sadly no. Bad part is mine works fine. The plastic body where the threads are is cracked. Got it to quit leaking so this Autozone one will be a spare. If my wire was broken I would try this though.

Oh that $22 is for a sensor for an '88. They don't list one for and '89. I've already made an adapter for the 86-88 connector cause that's what my current one is.

 

Great write-up and one which I may be using soon; my wire it about to separate form the sensor. One more disconnect and its toast.

May I make two suggestions to add to your procedure?

First, prior to starting, fully install the sensor and mark it for best wire exit position. That way, when you install it, it pointing in the right direction.

Second, when installing the heat shrink tubing, cover the pen spring, too. Your instructions imply this, but your photo didn't show it.

 

yeah i forgot they now offer the sensor aftermarket, it was only up until several years ago that only the factory offered them and at close to 50 bucks and failing regularly it was a nuisance even touching those sensors.