18 gallons distilled water to flush Sequoia cooling system.

Joined
Apr 27, 2010
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Suburban Washington DC
2003 Sequoia coolant change.jpg


Main issue was that both radiator hoses connect to the top of the engine, so draining the radiator will get nearly nothing out of the block not to mention the heater cores. Yes it had drain valves on the block, but I wasn't about to risk snapping them off on a 1/2 million mile engine and creating a much worse problem. So for a few cycles of drain, fill, drive drain, I was only able to add about one gallon of water at time and the stuff draining out was not getting visibly cleaner.

Checked on the Toyota forums and found that you could disconnect the oil cooler water hose at the filter, and that would drain the block better then the drain valve. So I did that and was able to add two gallons of water at a time. Did that half a dozen times until finally the water draining out was clean. Refilled with 2 full gallons of extended life Peak Asian red/pink concentrate. This is the only full strength extended life coolant made that was available at a reasonable cost. Will check freeze protection after a few drive cycles to get it fully circulated, but with a total capacity of 14 quarts, it should be better than 50% concentration.
 
Joined
Jan 9, 2010
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Los Gatos, CA
Looks good... I am just gonna do a radiator spill and fill on our trusty '01 Tundra with the 4.7.
Where is the oil cooler line you mentioned exactly?
 
Joined
Jan 3, 2020
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YYC
A bit overkill since Toyota's FSM procedure for a coolant change is just to drain and fill the radiator. The 4.7L's in the Toyota trucks have the only iron blocks they made at the time so maybe you have a corrosion issue.
 
Joined
Jul 23, 2021
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PA
You probably did a great service to that vehicle. Good work.

In the future a MityVac might help greatly. I'm about to do several vehicles with the MityVac topside, so as to not risk damage to any hoses or peacock valves, etc. I've been able to get around 6 liters out of my various radiators thus far with the MV.
 
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