Block drain plugs - ZR 409

[Boats Bros]

This guide has pictures of where all the sensors are.

https://pcmengines.com/wp-content/up...L510014-06.pdf

Thanks much! Looks like the coolant temp sensor is on the head and the sensor in question is an unused oil pressure sensor.

[scotchipman]

Boats Bros Attached is a picture of the top of my engine, I don't see a coolant temperature sensor in the location you have.

I did finally get confirmation that the big non standard hex nut circled in the above picture in this thread is the block drain plug for my 2015 ZR 409 6.0.

[scotchipman]

I saw this on Ball of Spray which sounds like the best option so far to drain the coolant.

Disconnect the expansion tank entrance hose and put it on a bucket, then with the boat running at around 2000 rpms fill the expansion tank with a different color coolant, when I see the new color coolant entering the bucked I stop the process.