So, I'm probably just nuking this one. The plan was to do a post-deployment coolant flush, then overhaul the entire cooling system. The overhaul isn't really negotiable, the upper radiator hose looks like someone tried to shove a baseball in it, the radiator's clogged with a slow leak, etc.

The argument is whether I attempt a flush with the nasty (and questionable) cooling system in, or after everything that can be replaced on the sucker has been?

I kinda feel stupid asking the question, even. I'll just convince myself to do the flush first, and then a few days later will start questioning the decision.

 

I'd flush it as much as possible with the crappy rad it it as it would bring the **** into the rad anyways..
And IF you are replacing the rad,then you get rid of alot of crap with it!

Then run it with some more flush and get the residue out when you have a good free flowing rad in there,to minimize any more debris that may be left in.

 

That's what I thought... thanks for backing up my sane side.

 

I would- and have- done it differently.

I'd pull the old radiator, all the hoses, thermostat and water pump, then flush out the shortblock as well as possible through the waterpump passages.
Put the new stuff in, fill with distilled water, run up to temp and then dump the water, checking how it looks.
When it runs clean, dump the water (if you've had to flush again), fill with coolant and bleed it out.

 

So flush sans thermostat? That was my primary concern for clog points, and I'm expecting this to be rather impressively bad, considering how the rest of the car's been taken care of.