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What's everyone take on GDI intake valve cleaning? I'll be doing the Seafoam intake spray soon and was looking for the good, bad, ugly or Fugly side of doing this process. I drive all highway miles and with almost 55,000 I have no issues with the 2.0T. Just doing some PM on the car.
 

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What's everyone take on GDI intake valve cleaning? I'll be doing the Seafoam intake spray soon and was looking for the good, bad, ugly or Fugly side of doing this process. I drive all highway miles and with almost 55,000 I have no issues with the 2.0T. Just doing some PM on the car.

Given how CRC has used the Sonata in their marketing material for their GDI cleaner, I'd feel better about using it EXACTLY as they recommend using it over any other products like SeaFoam, etc.


However, from what I have seen and heard, the really truly effective cleaning method is manual cleaning via taking off the intake manifold and accessing the eight intake valves. Various methods of doing that have been effective from walnut blasting (best) to soaking it with a cleaner (like SeaFoam) and scraping it (making sure the intake valves are fully closed on each cylinder you then clean to keep crap from getting into the bore and damaging it).


FWIW: I ran 93 octane gas (Top Tier), ran two OCCs (a very good version) and synthetic oil all for 76K miles with no real issues, however when I had my engine replaced, I did have a good look at the intake valves and they could stand a cleaning.
 

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Go for it. Sprays and IVD cleaners are available from CRC, Seafoam, Amsoil, RoyalPurple, 3m, Berryman, Gumout, ATP....
Dont forget to run a good FI cleaner too
 

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Discussion Starter #4
Thanks for the advice. I'll go with CRC cleaner and save the Seafoam for another vehicle. I'm gonna try to borescope the intake manifold and snake over to see the valves, but that'll be another weekend project.
 

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FWIW: Here is a picture of the Cyl#2 (worst one of the four) when my engine was replaced under warranty at 77K miles. I started running my OCCs (see signature) sometime around 20K miles or so. So as you can see, these valves could use cleaning (walnut blasting would be best) but I've seen worse on the interwebs. I'm now running both OCCs from the get/go on my new engine and believe running how I'm doing it (Castrol Edge 0W-40 oil, changing every 4K miles, Fram Ultra XG9688 filter) and 93 octane Top Tier gas (Costco, Exxon, Shell) will help slow but totally stop this GDI based effect.

442921
 

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FWIW: Here is a picture of the Cyl#2 (worst one of the four) when my engine was replaced under warranty at 77K miles. I started running my OCCs (see signature) sometime around 20K miles or so. So as you can see, these valves could use cleaning (walnut blasting would be best) but I've seen worse on the interwebs. I'm now running both OCCs from the get/go on my new engine and believe running how I'm doing it (Castrol Edge 0W-40 oil, changing every 4K miles, Fram Ultra XG9688 filter) and 93 octane Top Tier gas (Costco, Exxon, Shell) will help slow but totally stop this GDI based effect.

View attachment 442921
That's a fair bit of caking, but as you mentioned, there's much worse out there...
Also interesting to note is how the actual valve itself is virtually build-up free, and the majority of it is limited to the stem where you can clearly see the cut off point. This is different to some manufacturers where it gets worse the further down the valve.
This makes me wonder if it's the product of the dual injection on start up, which sprays fuel twice - once with the valves fully open, and once when fully closed.
It has been speculated my myself and others that this would keep the seating area of the valve free of build up, and would explain how Hyundai GDI engines are mostly free of the performance and economic impacts that other designs have.
@az2008 you may be interested in this pic haha
 

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I started running my OCCs (see signature) sometime around 20K miles or so. So as you can see, these valves could use cleaning (walnut blasting would be best) but I've seen worse on the interwebs. I'm now running both OCCs from the get/go on my new engine and believe running how I'm doing it (Castrol Edge 0W-40 oil, changing every 4K miles, Fram Ultra XG9688 filter) and 93 octane Top Tier gas (Costco, Exxon, Shell) will help slow but totally stop this GDI based effect.
@misnblu (on the RB Accent forum) is an advocate of catch cans. Apparently they catch/trap impurities/oil in the PCV air drawn into the intake. I wonder how much of that might contribute to the buildup people have with GDI (no injector in the intake to help keep it clean).

I've been thinking about adding a catch can to mine. It seems to make sense. (I'm a little skeptical because you'd think, if it made a substantial difference, Hyundai would have added one to the stock engine. I guess they collect oil and you have to drain it each time you change the oil. That might be why it's not stock. But, it seems like it could be designed (if Hyundai wanted to) to drain the recovered oil back into the pan.

It would be interesting if someone really into this buildup topic did some kind of before/after test to see if a catch can makes a difference. (Or, if one person did it while another didn't, and compared intakes after 100k miles, or something. I don't know.).

They don't seem expensive. $60 USD. They could probably be less expensive if not sold by the performance/modding places. (I think anything of that nature is marked up more than it would be if it were mainstream. But, it's still not very expensive.).
 

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The catch can or if you want an air oil separator will give your intake air a cleaner air to burn.
Misty oil and other junk from the crankcase can dilute the incoming air for less efficient burn thereby decreasing your power and fuel mileage.
It also lowers your octane of the fuel in your fuel/air charge by not having a catch can or air/ oil separator setup.
Heck my Chevy Z24 drag car had a factory air/ oil separator on it and at that time I was still ignorant of the full purpose of what they were for and why they work.
So @az2008 as you can see some car manufacturers do know about air/ oil separators and do implement them to their cars. The only difference with the Z was it was port fuel injected so the valves stayed clean.
For the gdi engine it is most certainly needed but there are some that have 250,000 miles on their engine and they run fine. 🤷🏼‍♂️
It won't hurt to have an occ as it does work and slows down carbon build up a lot. 👍
 

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2018 Sonata Limited 2.0T (DOM:11/09/17)
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@misnblu
... It seems to make sense. (I'm a little skeptical because you'd think, if it made a substantial difference, Hyundai would have added one to the stock engine. I guess they collect oil and you have to drain it each time you change the oil. That might be why it's not stock. But, it seems like it could be designed (if Hyundai wanted to) to drain the recovered oil back into the pan ...
I run a PCV-side OCC and find that I'm collecting more condensation base than oil crud; it could be from my short trips (<30 miles each way).
Maybe one reason that OCCs aren't factory equipment is that the actual diluted matter collected has a lot of moisture which, even tho drained at each OCI, could possibly freeze during the winter months and develop OCC cracks with damaging vacuum leaks/drivability issues.
And for sure, wouldn't want to have this matter drain from the OCC back into the pan.
 

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And for sure, wouldn't want to have this matter drain from the OCC back into the pan.
Why not? Without the catch can, wouldn't that stuff remain in the system? If so, a catch can would make no net difference in that regard. It would just keep that crap out of the combustion chamber (the main point I think people use a catch can).

EDIT: After more thought, a hypothetical maintenance-free catch can draining back into the sump probably would not be the same as having no catchcan (regarding moisture condensation being caught and returned). Without a catchcan, the condensate would burn off in the combustion chamber. I wasn't thinking about it properly.
 

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Why not? Without the catch can, wouldn't that stuff remain in the system? If so, a catch can would make no net difference in that regard. It would just keep that crap out of the combustion chamber (the main point I think people use a catch can).
Not sure if I understand your question. Please explain.
 
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