Cleaned EGR valve, not sure if full circuit is needed. 111k miles

Excellent pictures of the cooler. Again, worth noting this is at 111k miles. Can’t imagine any “cooling” took place with that. And only pinholes of flow left. It’s patently obvious Toyota rushed that nonsense to market without testing.

 

Escalate to lye (sodium hydroxide) solution? Hopefully available in the States, say on Amazon. We got some a few years back for soap making, on Amazon.ca. I noticed it's oddly missing from grocery/hardware store shelves. Apparently used in meth production.

If you're not doing this: most expedient is to cork one end of the cooler, then only about a cup of solution is needed. A bare wire run through the fins may expedite the solution's ability to penetrate.

Whatever solution is being used, I've found a one hour soak, then rinse and repeat, to be most effective, just judging from the amount of foaming reaction. It tends to be quite active at first, then subside.

Stumbled on this US lye source:

Online Store

 

You wasted 12 hours.
Oven cleaner. 30 minutes.. Pressure washer.
Repeat if needed....

 

If lye/sodium hydroxide/oven cleaner is used, follow up rinses should be made using very hot, near boiling water.

The sodium hydroxide and hot water converts the oils to a soap, which is then dissolvable in water. This should be much easier to blast through with the pressure washer.

If the sodium hydroxide isn't penetrating into the channels, you might need to drive a stiff, thin wire through as many channels as you can access. You won't be able to get at them all, due to the bends in the cooler inlet/outlet.

SM-G781V ?

 

Regarding the last picture of the cooler. No, that is not good enough. It should be very clean with all visible channels clear.

SM-G781V ?