I’m working on a 1988 formula 5.0 mpi auto. I was doing a spark plug change, car sat for 18 years, I noticed a wire hanging down that hat a pin on the end and part of a ribbed water tight boot. Between plug 4 and 6 there was also a sensor type device screwed into the block that looke to be where this plugged in. When I touched the plastic end of the sensor it disintegrated. I need help identifying it so I can replace the electrical connect and the sensor itself.

 

Knock sensor or cylinder head temp sw

 

https://ebay.us/m/nkb9h0

 

Plugs 4 & 6 are screwed into the head. The block is ... the block. Which is not the head.

Which is it?

If it is what it sounds like, which is, it has NOTHING WHATSOEVER to do with the head (spark plugs), butt rather is right exactly dead center front-to-rear of the BLOCK about an inch or so above the oil pan, it's the knock sensor, otherwise cleverly disguised as the pass side coolant drain plug. See, those [forrest_gump] smarrrrrrttt [/forrest_gump] engineers at GM, knew back in the early 50s, that electronically controlled fuel injection was a-comminn, and they made a provision for it, in "stealth mode" so that their competitors (the d00dz that placed lower in their graduating engineering classes) at Frod and Xler, wouldn't get a glimpse of what they were up to. So, they disguised the future knock sensor port, as a coolant drain. Clever. Genieass. Not sure I measure up.

So as said, what it sounds like you're working on, is the knock sensor. Be aware that it's also the pass side block coolant drain; therefore when you pop it out, there's a finite and VERY non-zero chance that EVERY BIT of the coolant in the engine except for about a gallon in the driver's side of the block, will come pouring out. Should be maybe 3 gallons or so, maybe a bit more. So be prepared accordingly. Great opportunity to do a COMPLETE coolant drain flush & renewal if you also take out the driver's side plug, all of which I highly recommend.

 

Thanks all. It looks like the knock sensor, the mushroom shaped plastic end disintegrated when I touched it. The wire hanging down still had a pin on the end but the outer plastic connector must have disintegrated too. Thanks for the heads up that the coolant will drain from them.

Dan

 

Hey Now!!!

Don't be tellin' all dems apeople all OUR aspecial seacrits now!


Just kidding!