Another EGR thread

The pressure is to force drops on a borescope test. It can look fine and should either way.

 

The pressure can hold either way

 

I think what rjparker is getting at is that you can use that pressurization kit to accelerate a borescope test—by pumping up a good pressure in the system, you can make drops form faster so you have a better chance of seeing them on your borescope—but that it wouldn't be a very sensitive test to just rely on watching for a pressure drop. Tiny drops slowly leaking just might not make enough difference in the gauge pressure to notice, or to tease out from the effect of, say, ambient temperature changes during the time that you're watching.

 

You'll be on a fool's-mission: when you drain the distilled water, you'll get 60~70%, and what remains will significantly reduce the overall percentage if you start with a 50/50 pre-mixed coolant. And how to responsibly dispose of all that drained, distilled water/glycol mix? If you're going flush, there's a link in my signature, just some thoughts. (one a phone turn it landscape to see signatures)

Do yourself a favor, just drain and fill. And ignore the repair manual guidance to drain the engine block; I did that the first time, think I got a couple of ounces.

 

When you drain the system, you only get 60~70%. If the only coolant available available is pre-mixed (and the hands-down favourite, Toyota Super Long Life, only comes thus), you have a quandary. Just drain-and-fill. Have a look through the attachment, the refill process is a little different, basically fill to the "B" line, cap everything, and run till fully warmed. And you need to put the car in maintenance, to prevent it shutting down. (the @NutzAboutBolts engine coolant change shows that well)

Worth noting: last change I did, I had the front raised, even during the warm up. I figured I'd warmed it sufficiently, crawled under to reinstall the engine underpanel, felt the coolant hoses down there, and they were still stone-cold. Started it up again (in maintenance mode), and just laid there, thinking about life, occasionally checking the hose temps. Finally the thermostat opened, and within minutes everything was toasty, done.

The link in signature about "flushing out engine stop-leak products" is more-or-less expressly for that: if there is a stop-leak product in the coolant, at least one product can apparently be flushed with a 50/50 mix of water and white vinegar, followed by repeated flushes. And then the conundrum of how to get back to 50/50. The only route I can see is to score some 100% coolant, say Toyota Long Life Coolant (note the missing "Super"), pour in half the spec'd system capacity, then top up with distilled water.

 

Here's an updated engine coolant change pdf, with Inspection Mode (aka Maintenance Mode) tacked on the end.

It's a verbose doc, here's the gist:

Perform the following steps from (1) through (4) in 60 seconds.

(1) Turn the power switch on (IG).
(2) Fully depress the accelerator pedal three times with park (P) selected.
(3) Fully depress the accelerator pedal three times with neutral (N) selected. (need to push brake to shift to N)
(4) Fully depress the accelerator pedal three times with park (P) selected.

 

If you have sealant to flush then consider multiple drain and fills. I would not put other chemicals in there since acidic conditions degrade seals and gaskets.

There is reasonable evidence even Toyota SLL left far too long could be a hg leak contributing factor, along with primary design issues resolved with gen4.

Multiple drain and fills could use distilled water for $1 a gallon but takes about ten times with the engine warmed up each time to sufficiently dilute KSeal (which is the only good reason to do multiple drain and fills).

No contaminates? No distill water yet? Use a gallon of SLL premix to fill it and you are good.

Otherwise use Toyota Concentrated which is cheaper. Figure you have half the fill with distilled water still in there and add a gallon of concentrate.

You are supposed to check the coolant condition with test strips every oil change anyway (brake fluid as well) and any coolant past the factory fill is 50k mile or less. Including SLL or Concentrate.

Unless you have a 2010, you won't have an air release valve and don't need to squeeze the radiator hoses.

If you do multiple distilled water flushes, use the gallon jugs the water comes in for the drained coolant.