Super deep-cleaned EGR cooler: Odd! Is this normal?

It will depend on how bad it is.
My pressure washer cleared out my spare cooler. But the oven CLEANER actually
CLEANED it. It was not really clogged.
My original one was clogged when I took it off. Took a few times to clear it out.
But after the initial clearing/cleaning, it's been easy to clear/clean it.

 

It is important to give ALL information at the begining... So you can get the best answers.
Doing a search on prius chat about egr cooler cleaning would have brought up all the answers.

Most stores have drain cleaner.....

 

I'm not saying that....
Each cooler is different. There are different methodes to use.
Since YOURS was a spare, you could have let it sit and soak for weeks if you wanted too.
There was no hurry to clean it, from my understanding.
Some need to use a wire in a drill to clear the passages, I didn't.

My main point was to give all information up front. You made it sound like you needed
to clean out the cooler fast because you needed it to get the car running.

It's like telling the doctor you hurt. And the doctor has to try to figure out where and why.
And says take 2 aspirins and call me in the morning.

And the next day you finally say, your leg. And it started after you got stabbed with a knife...

 

Really clogged EGR coolers (rock hard carbon, and oily goop) usually require busting through the channels with the wire so that any cleaners can get into the channels to do their thing.

Tip, after using lye, oven cleaner, flushing with near boiling hot water is most effective. In soap making, lye plus oil makes soap. In the EGR cooler cleaning, lye plus oily deposits converts the oils and grease into soap-like stuff that can be dissolved more easily with the hot water.

Edit: This is why most drain cleaners tell you to pour very hot water down the drain after treatment with the sodium hydroxide in the cleaner.

SM-G781V ?

 

I can’t see the EGR cooler being very oily though. It’s fed by exhaust, I think only dry carbon in that.

 

The residue in the EGR pipe coming out of the cooler and before the intake manifold was pretty oily.

SM-G781V ?

 

I disagree, provide vague and non detail descriptions makes it funnier for us to throw out random guesses.