I blew up the 4.0 in my jeep. So i got a used engine from a junkyard and tore it down to replace all seals, gaskets, and freeze plugs. I found this on the right front bottom side of block. As i have rebuilt many engines and was a mechanic for some time i have never seen anything like this. So i ask you to identify what this is

 

A pic would help.

 

 

?????????????

 

Still no picture.

 

Nope, I've never seen two boxes with red X's in any engine I've ever had apart.

 

Well I put them on there with my computer and I could see them when I posted it. I'll try again

 

Those are heat sensors that machine shops attach to the block. They melt at certain temps according to color. That way, when you overheat your rebuilt engine cuz you did something stupid, they tell you to take a hike cuz it isn't their fault.

 

Thank you sir. I have never encountered that or rember if I have. That makes all the sense in the world. Lol but I still feel like an idiot.