I wait until I don't burn my fingers on the radiator cap to drain/refill; I do a flush with the sodium citrate stuff and then 3 rinses, takes me an average of 2.5 hrs total. I seriously doubt your block is in jeopardy from dumping ambient temperature dH2O...

resurrecting a dead thread... hahaha...

use the red stuff!! $20 a pop but worth it...

Has anyone actually pulled the coolant drainplug on the engine block in addition to the radiator stop cock? It's a bear to find and access and in my limited experience, as long as you do a few flushes, even though you're not actually draing ALL the fluid each time, it does get most of it and my liquid is coming out nice and clean by the 3rd rinse. Just wondering...

 

I'm not going to got back and forth about this. But comparing a thermostat opening in cold weather to dumping in 50% or more of a cooling systems capacity with cold tap or room temp distilled water isn't the same.

I've seen first hand the results with a one of my neighbors and his Durmax diesel. He let it cool for about 30 min and then dumped the radiator and stuck a water hose in the radiator. About 5-10 seconds later we hard a loud pop but didn't think anything of it. Well he started it up and after running for a bit there was bubbles coming out of the surge tank.

That loud pop was the aluminum head contracting allot quicker than the block which caused a head gasket failure on the drivers side.

Back in the days when you had all cast iron and steel engines you could get away with allot more because the block and head all the same coefficient of thermal expansion. But now with aluminum heads and cast iron blocks and even worse the engines with aluminum blocks with steel cylinder liners you have to be allot more careful.



FOG

 

I tried but never could find that block plug. I think it's a myth, but I can't find the blinker fluid fill plug, either. I pull the T-stat and flush with a hose, my mountain well water has no metals or calcium and I have $500 of lab tests to prove it; it's actually officially too SOFT to drink. I'll run pure H2O on short runs around town for a day with no thermostat in warm weather and then drain, reflush and final fill. I do the final fill with distilled just from paranoia, even though I have done every other car I've owned with this well water and zero problems (it's a LOT of cars). I only run the hose through a cool engine, though, that water is 53°F year round.

I always use 50/50 Toyota Red. I let the dealer do the 30K and they took out the red and put in green. That was the last time the car went back there.

EDIT: Wow, old post. I have since found the block plug. It's really there.(9/20/15)

 

I have used the plug on the flushes I've done, makes the rinsing quicker.

I wish the block was the same on my Cummins, the plug gets maybe 3 more qts out, but still leaves about 2-3 gallons in the block... Flushing isn't near as easy.

 

found the drain cock for the 5vz it's on the pass side.... did the radiator today, new Koyo that looks better than the OEM one. And new hoses, yeah.

Two extensions on a 3/8" ratchet and a 14mm socket hits it perfect through the pass side wheel well.

bought the last gallon of Zerex from napa, lucky I had some left over from last flush so I could get the taco running again with fresh coolant.