Hello Fellas,

Is there any plugs or drains on the block somewhere to drain the coolant out to empty the system??

I want to replace it as maintenance.

Thanks in advance.

Same place as other BBC's. Lower sides of the block between the 4/6 and 3/5 cylinders.

Thanks. What type of fastener is it? Size?

its a 1/4" pipe plug, with what should be a 9/16" hex head.

How often should it be changed?

I always thought Dex-cool had a 5 year life, but I'm probably wrong

It's time. 5-6 seasons, give or take; or definitely when it looses it's pink appearance and turns silver/metallic.
It will not cool as well when it starts to go as it sludges up.

#11. Part # 22-36382 Pic of location and plug
http://www.mercruiserparts.com/Show_...nd+Camshaft%29

I'm probably due for a change. I'll add it to the list.

Just plain old Dex-cool? I'm sure Mercury has some snake-oil equivalant for $50 / gallon.

Plain old Dex-Cool.