2012 Prius v owner, but I thought to post here about my question as the ECR cooler is a common part, and thought there may be more traffic to the Prius liftback tech section. I am trying to understand the differences between the EGR cooler for the gen 3 (part number 25601-37010) and 2015+ which have a part number of 25601-37020. Anyone know if there are any physical differences between the two, that would result in the newer part not fitting into a 2012? There seem more used parts for less money, for the newer units which also have much less miles. Anyone have any experience with this?
No experience, but I have heard the newer ones source exhaust differently (from after the converter), so likely are not interchangable.
Maybe somebody will try blocking off the bung on the exhaust manifold, and adding one to the pipe downstream of the converter, and shoehorning a Gen 4 cooler in somehow.
Spoke to my mechanic yesterday and he said to not mess with trying to use different part numbers, regardless of how similar they look.
This thought has crossed my mind as well, but I'm also wondering if the Gen 4 cooler itself is a better design, or if we wouldn't be equally well served to just move the location the exhaust gas is drawn from to post-cat and extend the EGR pipe from that point to the gen 3 cooler
@Ragingfit elects to retain his 3rd gen intake/exahust manifolds, and EGR system, when swapping a 4th gen engine into a Prius v (essentially the same process as swapping into a 3rd gen Prius) here: Swapping in a Gen 4 Prius' 2ZR Engine into the Prius v | PriusChat Exhaust manifold differences discussed here: I think with enough mods it could be done. But maybe not worth it. FWIW, about 18 months and roughly 10K kms after doing the EGR and intake manifold clean, and Oil Catch Can install, when I checked the EGR pipe recently, it was spotless.
I was wondering if I'd understood, but yeah, that last part number is 4th gen Prius EGR cooler. Part #11: EGR System for 2016 Toyota Prius | Toyota Parts
From Toyota's part diagrams, the gen 4 EGR cooler looks wider/shorter. Maybe less prone to blockage? It makes sense to make it wider since the EGR flow increased in the Gen 4 from 21% to 28%. It would be nice to see a side-by-side photo of Gen 3 EGR cooler vs. Gen 4.
You can see the difference in the exhaust manifolds: For 2016+ Toyota has moved the catalytic converter further upstream, just behind the header collector. This allows them to "roughly" keep the EGR cooler and exhaust to EGR pipe in the same place and downstream of the catalytic converter, drawing "cleaner" exhaust gases back into the engine. It also allows for faster converter heat up, reducing emission quicker after start up. I am sure it's possible to use the 2016+ EGR setup on a 2010-2015 model, but not without some moderate exhaust work. It may be possible to swap over the entire exhaust system.... making this easier. Or it maybe swap over partial exhaust system, welding them together further downstream. -A
Got a bunch of discussion over in this thread here. Turns out the difference between tapping the EGR from upstream or downstream of the cat is a big deal. Downstream is an entirely different, newer technique with its own name ("catalyzed EGR" or "clean EGR") in the engineering literature, and so while, yeah, you might guess there's less gunk in it, it is also a different chemical composition because of the cat's action, and lower pressure because of the cat's pressure drop, so it needs upsized cooler and valve even just to get the same flow, and it has different effects on combustion because of the chemistry, and engines using the two techniques are designed and calibrated for them specifically. Needless to say, that makes it something more than a trivial swap.