Flushing old coolant - Remove block coolant drain plug, or not?

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Intake is off, water pump off and heater hoses disconnected.
Had problem with tranny fluid in engine coolant, that problem is resolved.
Before disassembly, I did several drains and fills, while running engine and flushed system with degreaser/cleaner designed for cooling systems.
Fluid appeared to be pretty clean at that point
Both heater cores have had hoses removed and individually flushed
My question is at this point, is there any reason to remove the block drain plugs and flush the block keeping the thoroughly flushed heater cores isolated from the system before putting it back together?
I also have a venturi coolant vacuum system, is that as good as flushing the block independently from the rest of the system?
Am I asking for problems if I get into trying to remove a block drain bolt on an engine this old?
 
I would remove it depending on what type of block drain. Block drain on my Volvo 240 is super easy, and only requires my fingers to tighten and loosen. If it's a thread in the block, and you can get an impact on it then I would remove it. If I had to use a wrench or six point socket to get at it, then I would just leave it. Might turn into a big mess!
 
I think you're fine without touching them, unless of course they're easy to get to and won't break (which usually is not the case).

I remember when I owned a Lexus LS460...went to drain the block thinking...oh this will be important...yeah it was important till I realized it'd be easier to pull the engine.
 
A small amount of transmission fluid in the coolant won't hurt anything. You got most of it out so I wouldn't worry about it.
 
Originally Posted by demarpaint
I wouldn't tempt fate removing the plug in the block.


+1 At that age you never know if it will even budge, forcing the issue may cause issues you don't to deal with. Whenever faced with a decision like this where it is not a "must do or else" job I go by what was taught me by a much better mechanic than I am, if the risk outweighs the reward then frig it and leave well enough alone.
 
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