What is this on my 4.236?

[skwanderer]

As I get more familiar with working in my twin perkins 4.236 diesel engines, I’m seeing more things appear, such as thislittle bolt with a valve on the side of the engine… help in identifying what this is and what I can/should/shouldn’t do with it would be greatly appreciated.

[Bill O]

That is the block drain plug for coolant.

Usually that is just a hex head plug, but it appears that someone may have fit yours w/a valve (to make it easier to drain??)

[skwanderer]

Thank You!!!