Is cylinder 4 mod necessary…

[ProudBoy267]

I’ve been reading tsb’s and opinions on a few different Subaru forums including this one. Some say it’s true some say it’s not. Can someone tell me definitively that on 2020 and 2021 wrx’s Subaru fixed the cylinder 4 cooling issue and the get-a-Dom cylinder 4 cooling mod isn’t required on the newer fa20s from 2020 and 2021s…. This sucks finding conflicting information. Anyone with a 2020 or 2021 bought the cooling mod and went in there just to see it’s fixed from the factory?

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[K3rm1tth3fr0g]

Originally Posted by ProudBoy267

I’ve been reading tsb’s and opinions on a few different Subaru forums including this one. Some say it’s true some say it’s not. Can someone tell me definitively that on 2020 and 2021 wrx’s Subaru fixed the cylinder 4 cooling issue and the get-a-Dom cylinder 4 cooling mod isn’t required on the newer fa20s from 2020 and 2021s…. This sucks finding conflicting information. Anyone with a 2020 or 2021 bought the cooling mod and went in there just to see it’s fixed from the factory?

Well considering Dom designed the cooling mod around the EJ motor, there's no reason it would fit in the FA unless Suabru specifically included the exact same port as they did on the EJ for some reason other than the twin turbo model existing, which is why the EJ has that port in the first place.

And honesty even if they did include that port for some other reason, the coolant system of the FA is different than that of the EJ, and the cooling mod was designed with the EJ flow paths in mind.

So no, the cyl 4 cooling mod is the for the EJ not FA.

[2018wrx_newbie]

That's for the STI, not WRX.

[Cody6182]

Everyone I have spoke with has informed me the problem has been fixed , but like you would also like a definite answer yes or no .

[GoFrogs]

Originally Posted by Cody6182

Everyone I have spoke with has informed me the problem has been fixed , but like you would also like a definite answer yes or no .

Clarification is needed in the above statement. What problem has been fixed; where and on what and said by whom? Too many unknowns or generalizations.

As far as the cyl-4 cooling mod goes, as K3rm1tth3fr0g said, it was designed for the EJ25 (STI) engine.

The FA20DIT does not need the cyl-4 cooling mod and I have not seen the mod/kit marketed as such for going on the FA20DIT.

[benflynn]

Is the knock sensor on the fa still over cyl 4? Where is the front mount turbo cooling from?

[Cody6182]

***128077;***127995;...I wasn't giving any definitive answers to it . I too have read about the issue and wanted to know as well , because many people have "said" it was , so I chimed in to say that I too would like a definable answer to it . My comment was totally misunderstood . I will be more precise when I post or comment on here from now on . First time on a car forum in 20 years , so I'm definitely rusty .

[tegxsi]

Cylinder 4 cooling mod is for EJ only!

Turbocharged EJ's are well known for ring land failure in cylinder 4. High knock events can crack the ring lands. The cooling mod redirects coolant flow to help cool cylinder 4 better. This helps reduce detonation/knock and lowers EGT.

FA have been revised. Ring land failing is not a weakness on the FA.

[Cody6182]

Thanks for that info ***128077;***127995;