Cursed Water Plug

by Pete Hodge

If your engine overheats and you have steam coming from the back of the engine just below the crank angle sensor, you probably have a burst "cursed water plug". It is easy to replace.

The 1.6 liter engine (and maybe the 1.8) has an unused water nipple on the back of the engine just under the crank angle sensor. The nipple has a rubber cap held on with a hose clamp. After 17 years, the cap on my '91 BRG broke and needed to be replaced. The part # is FEA7-13-104. I recommend the Mazda OEM part. The generic replacement I used the first time broke after only 1 year vs the 17 years of the OEM part.

To replace the part working from the passenger side of car:

1. disconnect the three electrical connectors going to the crank angle sensor and push out of the way.
2. remove hose coming from the brake master cylinder area to top of gas rail.
3. using a flashlight, you can locate the cap and nipple. It is just under the crank angle sensor.
4. remove hose clamp from nipple.
5. pull off defective cap
6. reverse above for installation.

I don't remember what the original hose clamp was like, but it probably was a standard OEM crimp clamp which can be removed with pliers. I used a screw type replacement clamp which is easy to tighten using a small 1/4 inch drive wrench with 1/4 inch socket. Be careful not to drop the wrench. It may land on top of the transmission. To locate it you may have to jack up the car and fish for it from underneath.

If your car is an older one, you may want to replace this part before it breaks as a preventative maintenance item. It may keep you from being stranded on the side of the road. FWIW, mine broke after 17 years and about 140k miles. The cost of the part is approximately $9.00 and 1/2 hour to replace vs the cost of a tow.