Hi all, 2012 prius with 200k miles. About to tackle the head gasket job the gen 3 is plagued with. Of course I was planning on cleaning the hell out of the EGR valve while I'm in there (never been done). Just an opinion question really... Would you replace the valve and cooler while you're in there? I know one answer will be : "if you feel like spending a few hundred go for it" Mind you-no signs of a faulty one. Passes emissions yearly, good acceration, no knocking. Kind of a tough question to answer i know. Comes down to $$$ I guess
The EGR valve may need replacement, if there’s a groove worn like this: this is looking at the interior of the cap that’s inside the EGR valve. For the EGR cooler cleaning should do the trick. With 200k I’d go with lye solutions, cork one end, fill, prop up and allow to soak for an hour, rinse and repeat as needed. Running a slim wire through to open it up some, may be needed. The EGR pipe, being stainless steel as well, you can use lye solution, but probably overkill. Everything else I’d use brake cleaner, just enough, and brushes, rags, and elbow grease. Definitely don’t use lye on anything that’s not stainless steel. Also don’t use bleach on stainless steel. see the links in my signature for relevant links, both for EGR and head gasket. Bottom link is full engine section from Repair Manual. (On a phone turn it landscape to see signatures)
In case it's not clear what groove Mendel meant in that photo, here's a photo with the "ski jump" undamaged on the left, while the one on the right has a rut worn through it,
