Engine Block Coolant Drain?

[Rocko973]

For someone doing a coolant swap, do you GM Techs NOT recommend draining the block from the two drain plugs underneath? It's not in the GM manual, and I am wondering why it's not in their manual, because wouldn't you want to try draining as much as you can before refilling with new coolant? And what do you think about in addtion to refilling via the reservoir per the manual, but also filling the engine block through the hose that leads into the radiator inlet tank, especially if I drained the block through the plugs? THis would be for 2003 Silverado 1500 HD, CC. Thank You!

 

[8.1HD/ALLISON]

Actually the plugs are for casting purposes.

http://en.wikipedia.org/wiki/Core_plug

[Duelin]

Sometimes when you remove those plugs it will bring the thread out of the block with the plugs.

[8.1HD/ALLISON]

I see no problem. Never heard of pulling threads. I would replace the o rings on them.

[bossier62guy]

Didn't we cover this a week or so ago?

[txab]

Yep

 

http://www.gm-trucks.com/forums/topic/151308-coolant-drain-from-engine-block/

[Jsdirt]

I never go that crazy doing a coolant flush. I figure by the time anything builds up in there, the truck will have fallen to pieces around the engine anyway.

 

The main purpose of those plugs is to drain the block completely during an overhaul. Sucks when you flip the engine on the stand after yanking the heads, and 2 gallons of coolant pours out all over your workspace.