Knock sensor ?

[Edwards85]

Marine Power 340, 2005 24v

Knock sensor L0456126

Took knock sensor out and the end of the sensor looked like there is build up on end and some of it pealed off. I am not a mechanic so is this build up or the way it was built? If build up on end should I clean it off or leave it?

[ericinmich]

I would scrape the bottom off and look closer. It seems like the rounded metal part (cap) is gone. If you scrape it off and it looks like a cap on the bottom then you should be fine. In a past life I was a spark/knock calibrator on these types of sensors (resonant) and flat response sensors on GM engines. These have a tuned mass that rings/resonates like a bell at a predetermined frequency. That frequency is a function of the engines primary knock modes (relates to bore & stroke).

These sensors use a single wire and require a good electrical connection between the sensor threads and the block.

Sorry I can't help more, I have never seen the end look like that.

[talltigeguy]

Isn't that just hard water deposits? If so, you can scrape it off, and some people will also use a hanger in the hole to be sure that the hard water/calcium buildup doesn't stop all of the water from draining from the motor.