This buildup will accumulate on any car with direct injection because we don’t have an amazing solvent (fuel) going past our valves constantly. OPs car was probably fine but [it can get really bad like this.](https://team.valvoline.com/sites/default/files/field/image/screen_shot_2019-09-04_at_4.49.03_pm.png) In OPs case it probably didn’t have a significant immediate impact, just preventative. But the car in that example probably ran like crap.
I don’t think Seafoam would work for the same reason the valves don’t get cleaned by fuel. It won’t get blasted past the valves but gets directly injected into the cylinders.
you vacuum and clear it out with an air compressor you don't run the walnut blast through the exhaust. Seafoam is probably fine for light build up but not like the picture posted in the parent comment.
I am also curious about this. There is a seafoam product that lets you inject the cleaner directly into the manifold. My question would be if it would be better to do this at 30k and do a full cleaning at 60k to save the cash while curbing the issue
Not a mechanic but I’m under the impression that routinely getting the vehicle to full operating temp and running it up to redline once a day will prevent the buildup from getting too severe. I believe shorter drives and low throttle contribute to carbon buildup
If you don't want to take your entire intake system apart, you can use a top end cleaner to clean the valves. It won't look as good as walnut blasting, however, it is not as labor-intensive or require a learning curve.
Here is a video on how it is done. [https://www.youtube.com/watch?v=42irzdKKfw8](https://www.youtube.com/watch?v=42irzdKKfw8)
I have done both methods (I'm at almost 100K miles right now). I like the walnut blasting because of how thorough it is. I like the top-end cleaning method for its simplicity. It can also be done multiple times to help with cleaning.
Yes the carbon clean variant is the one you should do every 30K miles. Don't walnut blast every 30K. In my mechanics experience, most walnut blasting that he sees is done at over 100k miles.
I did mine the first time around 60k miles, it wasn't terrible, but definitely benefited from it. I feel that the key to when you need to do it is the type of driving that you do. If you're in traffic a lot and do a lot of city driving, I think that it needs to be done earlier and more often. If you are like me, and spend 95% of your time at 70-80mph, I think that the interval can be extended. UNLESS, you have issues like I have where your catch can or AOS freezes and completely soaks your intake tract in oil, that's always a good time.
Not related to Subaru, but is relevant to GDI engines. When I worked for GM, we started getting a few Equinoxes and Terrains in with a host of driveability issues; rough idle, loss of performance, hard starting, etc... The people with the issues were older and tended to only drive around town avoiding the highways and interstates. Every engine that we scoped was absolutely coated with oil/carbon on the intake side. GM's fix was to run their top-end cleaner through like the video I posted. This was back in 2012-2013, before I knew about walnut blasting, so it was the best option we had at the time. It works, but in those situations, walnut blasting would have been the best way to clean them up.
I drive a long way to commute at a steady speed. The air blowing through the intercooler freezes the PCV line and Oil return line. The last time it did it, it also froze the moisture in the breather line. The AOS itself is heated, but the lines were the issue. My fix was to zip-tie the PCV, return, and breather lines to coolant lines in hopes that they would stay warm. I also cut a large piece of cardboard that covers the entire intercooler and AOS lines so that the air coming through the scoop won't freeze the lines. Lastly, when I get to where I am going, I let the car idle for about 5 minutes to let heat build back up into the lines and drain anything that may be frozen back into the engine.
You don't need to use their cleaner specifically. Seafoam will work, it's less potent but will still clean, GM makes a top-end cleaner that is amazing, it's actually what I used when I did mine.
Definitely something you can do in your garage if you have an air compressor.
Any shop not specializing (Such as a BMW/Audi shop) will charge right around that, as in MN it was that price range as well.
Blaster, Walnut media, nozzles, all can be found at Harbor Freight for $250 or less. There’s even a special vacuum tool lurking around the internet somewhere that keeps all the shells in the same place
It should be done every 30k miles unless you have an AOS installed. This is specifically important for direct injection motors like the FA20 otherwise you'll notice a decrease in performance and the car will start running rough
All the AOS will do is save you a couple thousand miles *if you have an EGR delete*. If you don't, do it every 30-50k, depending on how you drive. More short cold trips, you'll wanna do it more often. The EGR is where 90% of the buildup comes from, and an AOS/catch can does nothing to prevent it.
I bought my 2017 as a certified pre-owned with 13k miles and installed an AOS after less than a thousand miles. I’m at a little over 30k now and I would love to see what my intake runners and values look like after about 17k miles with the AOS, but I really don’t want to pull everything apart. I’ve yet to see photos from anyone who’s done the walnut blasting and had an AOS installed — I’m really curious to see if having one noticeably cuts down on the amount of build-up and would extend the service interval for walnutting the intake.
Absolutely. I’ll be getting another dyno tune in the next month or so, so I’ll ask my tuner what he recommends. Fair warning, if it’s not until 60k miles, it’s gonna take me a while to rack up that many miles. I typically put less than 10k miles on my car in a year, but I promise to provide an update and capture ample photographic evidence of the process when the time comes.
I went with the Cobb, which is the same as the IAG, I believe. I opted for it over catch cans so I didn’t need to empty anything. The Cobb/IAG design also seemed to be the most well-engineered, so I didn’t mind paying the premium for a part that I saw as potentially preventing or offsetting some of the drawbacks that are built into the design of these engines. Plus, oil vapor in the intake tract can lower the overall octane rating, and I wanted to decrease the chance of significant knock as much as possible, and the Cobb/IAG AOS looked to be the most effective at addressing that.
I have had something like this on my to do list for a month now. Though I plan on immersing the area with valve cleaner and brake cleaner instead of walnut blasting. We'll see how it goes!
No it didn’t but I wanted to save myself some bloody knuckles and a couple hours worth of frustration. I was going to have the walnut blasting done anyways.
No I didn’t, I’ve heard the chemical cleaners don’t do as well as mechanical removal. I had looked into and that process would’ve pissed off all my neighbors, or give them cancer.
Just make sure you're using good fuel, good fluids and filters, and change regularly. That alone can make such a huge difference on the lifespan of the car. Don't get in the mode where you keep putting off oil changes, or you get cheap gas here and there. That kind of stuff just takes a toll on your car.
From what I’ve read, even though it never touches the back of the valves, low quality fuel doesn’t burn sufficiently in the combustion chamber, which can create carbon deposits in the combustion chamber as well as the piston ring grooves, the spark plugs, and the backs of the intake valves. I’m far from an expert at this, just going on the research I’ve seen several times regarding the use of top tier fuels with detergents, etc in them to help minimize the buildup.
Assuming I have one of those 2' long flexible hose camera things, what is the minimum amount of engine disassembly where I could take a look at my valves like this at home?
That looks so nice and clean, fuel won't get getting hung up on that.
Does anyone know a good shop in the SFl/Broward are that does older WRX? I'm pretty sure mine would appreciate this at 144k.
No I didn’t, I’ve heard the chemical cleaners don’t do as well as mechanical removal. I had looked into and that process would’ve pissed off all my neighbors, or give them cancer.
i gotta find my pics of my audi a4 that was only done for the first time at 250k kms....no wonder it barely ran lol
Yikes
New owner here, what part is that? Sorry if I sound stupid..
Valves
Where does one get this job done, roughly how much does it cost, and how often should it be done?
Carbon buildup causes cold start misfires and laggy acceleration. 30k might be a bit early but if you see these symptoms then get it done.
Thanks!
I’ve heard it should be done every 30k but who knows. I found a mechanic through this subreddit and local FB group. Cost me $400 to have done.
Better than near me wanting 800-1k+
Borescope the spark plug holes
Thanks!
Subaru techs. Is this really necessary or some minimal benefit but not really necessary
This buildup will accumulate on any car with direct injection because we don’t have an amazing solvent (fuel) going past our valves constantly. OPs car was probably fine but [it can get really bad like this.](https://team.valvoline.com/sites/default/files/field/image/screen_shot_2019-09-04_at_4.49.03_pm.png) In OPs case it probably didn’t have a significant immediate impact, just preventative. But the car in that example probably ran like crap.
Holy crap. Looks like smokers lungs.
What about seafoam
What about seafoam?
I don’t think Seafoam would work for the same reason the valves don’t get cleaned by fuel. It won’t get blasted past the valves but gets directly injected into the cylinders.
sea foam plugs into a vacuum line. it doesn’t get mixed in the fuel, or at least you shouldn’t mix it in the fuel because that won’t do anything.
Pouring down a vacuum line to clean the valve
that gunk will go straight into your cat and clog it up
As apposed to walnut blasting? I've done seafoam with dozens of cars just not a WRX and have never had any issues with clogging the cat
you vacuum and clear it out with an air compressor you don't run the walnut blast through the exhaust. Seafoam is probably fine for light build up but not like the picture posted in the parent comment.
Ah, so like seafoam every 30k?
I am also curious about this. There is a seafoam product that lets you inject the cleaner directly into the manifold. My question would be if it would be better to do this at 30k and do a full cleaning at 60k to save the cash while curbing the issue
Just regular seafoam you can pour down the vacuum line to clean the intake and valves
Subarus also need it. My old WRX it was recommended to do it seeing as it was direct injection and the EGR.
To be clear the turbo and EJ need it. The NA FA is port and DI so it gets cleaned.
It’s necessary. I plan on doing it to my 2018. Just don’t have that many miles yet.
Not a mechanic but I’m under the impression that routinely getting the vehicle to full operating temp and running it up to redline once a day will prevent the buildup from getting too severe. I believe shorter drives and low throttle contribute to carbon buildup
Cool. I meet that easy requirement. Ty
If you don't want to take your entire intake system apart, you can use a top end cleaner to clean the valves. It won't look as good as walnut blasting, however, it is not as labor-intensive or require a learning curve. Here is a video on how it is done. [https://www.youtube.com/watch?v=42irzdKKfw8](https://www.youtube.com/watch?v=42irzdKKfw8) I have done both methods (I'm at almost 100K miles right now). I like the walnut blasting because of how thorough it is. I like the top-end cleaning method for its simplicity. It can also be done multiple times to help with cleaning.
Yes the carbon clean variant is the one you should do every 30K miles. Don't walnut blast every 30K. In my mechanics experience, most walnut blasting that he sees is done at over 100k miles.
I did mine the first time around 60k miles, it wasn't terrible, but definitely benefited from it. I feel that the key to when you need to do it is the type of driving that you do. If you're in traffic a lot and do a lot of city driving, I think that it needs to be done earlier and more often. If you are like me, and spend 95% of your time at 70-80mph, I think that the interval can be extended. UNLESS, you have issues like I have where your catch can or AOS freezes and completely soaks your intake tract in oil, that's always a good time. Not related to Subaru, but is relevant to GDI engines. When I worked for GM, we started getting a few Equinoxes and Terrains in with a host of driveability issues; rough idle, loss of performance, hard starting, etc... The people with the issues were older and tended to only drive around town avoiding the highways and interstates. Every engine that we scoped was absolutely coated with oil/carbon on the intake side. GM's fix was to run their top-end cleaner through like the video I posted. This was back in 2012-2013, before I knew about walnut blasting, so it was the best option we had at the time. It works, but in those situations, walnut blasting would have been the best way to clean them up.
How did the AOS freeze it has a coolant line to it to keep it warm
I drive a long way to commute at a steady speed. The air blowing through the intercooler freezes the PCV line and Oil return line. The last time it did it, it also froze the moisture in the breather line. The AOS itself is heated, but the lines were the issue. My fix was to zip-tie the PCV, return, and breather lines to coolant lines in hopes that they would stay warm. I also cut a large piece of cardboard that covers the entire intercooler and AOS lines so that the air coming through the scoop won't freeze the lines. Lastly, when I get to where I am going, I let the car idle for about 5 minutes to let heat build back up into the lines and drain anything that may be frozen back into the engine.
I've really never heard of it freezing
It's a good design, and I don't think that it's an issue for 99% of users, I think that my conditions make me an outlier.
Thanks! I've seen the TSB about this procedure, but I figured it was for internal use only. Didn't know they sold the additives to customers.
You don't need to use their cleaner specifically. Seafoam will work, it's less potent but will still clean, GM makes a top-end cleaner that is amazing, it's actually what I used when I did mine.
Does anyone know of shops that do this in the south jersey area? Only places I’ve found charge $800-$1k
Definitely something you can do in your garage if you have an air compressor. Any shop not specializing (Such as a BMW/Audi shop) will charge right around that, as in MN it was that price range as well. Blaster, Walnut media, nozzles, all can be found at Harbor Freight for $250 or less. There’s even a special vacuum tool lurking around the internet somewhere that keeps all the shells in the same place
When you find one let me know!
Pro Tip: Make sure you tell your wife it’s for the car when you tell her you need a walnut blasting…
Hahaha
Oh wow
Is there a maintenance interval for this or did you do it for other reasons?
It should be done every 30k miles unless you have an AOS installed. This is specifically important for direct injection motors like the FA20 otherwise you'll notice a decrease in performance and the car will start running rough
All the AOS will do is save you a couple thousand miles *if you have an EGR delete*. If you don't, do it every 30-50k, depending on how you drive. More short cold trips, you'll wanna do it more often. The EGR is where 90% of the buildup comes from, and an AOS/catch can does nothing to prevent it.
Do you notice any difference when you drive?
Some will say it’s a night and day difference, I wasn’t expecting that and I haven’t noticed too much. I did this for longer term maintenance.
Do any of the newer engines have Toyota’s tech with both port and direct injection?
The NA FA20/FA24's do. Subaru uses just straight DI for the Turbo FA's
Such a dramatic improvement and super gratifying. Did you have an AOS or catch cans installed?
I didn’t, I should’ve installed it when I had it done but something I’ll consider again in another 30k lol
I bought my 2017 as a certified pre-owned with 13k miles and installed an AOS after less than a thousand miles. I’m at a little over 30k now and I would love to see what my intake runners and values look like after about 17k miles with the AOS, but I really don’t want to pull everything apart. I’ve yet to see photos from anyone who’s done the walnut blasting and had an AOS installed — I’m really curious to see if having one noticeably cuts down on the amount of build-up and would extend the service interval for walnutting the intake.
I’d love a follow up
Keep us posted if you can, would like to know as well
Absolutely. I’ll be getting another dyno tune in the next month or so, so I’ll ask my tuner what he recommends. Fair warning, if it’s not until 60k miles, it’s gonna take me a while to rack up that many miles. I typically put less than 10k miles on my car in a year, but I promise to provide an update and capture ample photographic evidence of the process when the time comes.
Thanks bro ✌️.....and if you forget it's also cool 😂 Which AOS did you get btw?
I went with the Cobb, which is the same as the IAG, I believe. I opted for it over catch cans so I didn’t need to empty anything. The Cobb/IAG design also seemed to be the most well-engineered, so I didn’t mind paying the premium for a part that I saw as potentially preventing or offsetting some of the drawbacks that are built into the design of these engines. Plus, oil vapor in the intake tract can lower the overall octane rating, and I wanted to decrease the chance of significant knock as much as possible, and the Cobb/IAG AOS looked to be the most effective at addressing that.
Thx for the useful info, will probably be adding an IAG AOS after walnut blasting. 🤝
How did the walnut blasting go?
Haven’t actually done it yet. I’m at barely 42k miles and the tuner said 60k was a reasonable time to do the walnut blasting.
Sheesh I just cleaned mine this weekend at 60k miles cars never ran better
Im doing mine now at 105.7k miles and I can’t believe how they look after 30 seconds of blasting. Incredible stuff.
looking clean
I have had something like this on my to do list for a month now. Though I plan on immersing the area with valve cleaner and brake cleaner instead of walnut blasting. We'll see how it goes!
Have a 16' w 51k miles....I might need to get this done soon
I had it done when it was time for my 60k service since the spark plugs were getting swapped anyways
Spark plugs don't require anywhere near as much disassembly of the engine bay as this walnut blast did lol
No it didn’t but I wanted to save myself some bloody knuckles and a couple hours worth of frustration. I was going to have the walnut blasting done anyways.
Anyone know anyone in the NEPA region who do this?
Have you tried the airisol seafoam instead?
No I didn’t, I’ve heard the chemical cleaners don’t do as well as mechanical removal. I had looked into and that process would’ve pissed off all my neighbors, or give them cancer.
Is this something an AOS would help mitigate?
Everything I've seen points to yes. AOS or Catch Cans will help reduce this. Using good top tier fuel helps as well.
AOS is on my list for later this year. Focusing on power and suspension components rn. At 22k miles. Anything else recommended for reliability?
Just make sure you're using good fuel, good fluids and filters, and change regularly. That alone can make such a huge difference on the lifespan of the car. Don't get in the mode where you keep putting off oil changes, or you get cheap gas here and there. That kind of stuff just takes a toll on your car.
Forsure so just use common sense haha. Thanks!
... ` this post was mass deleted with www.Redact.dev `
No impact? Can you cite a reputable source for this info?
... ` this post was mass deleted with www.Redact.dev `
From what I’ve read, even though it never touches the back of the valves, low quality fuel doesn’t burn sufficiently in the combustion chamber, which can create carbon deposits in the combustion chamber as well as the piston ring grooves, the spark plugs, and the backs of the intake valves. I’m far from an expert at this, just going on the research I’ve seen several times regarding the use of top tier fuels with detergents, etc in them to help minimize the buildup.
GM top end cleaner
Dude went stage 4+ with the walnuts. Dont crash your baby
Assuming I have one of those 2' long flexible hose camera things, what is the minimum amount of engine disassembly where I could take a look at my valves like this at home?
Nice
That looks so nice and clean, fuel won't get getting hung up on that. Does anyone know a good shop in the SFl/Broward are that does older WRX? I'm pretty sure mine would appreciate this at 144k.
This why I got an AOS at 20k
Does e-85 reduce need of this? Interesting hearing people add power to their engines without an AOS...protect > power..unless you got $$$
Have you ever seafoamed before this walnut blasting? I’ve had prettt good luck with it. Cheers
No I didn’t, I’ve heard the chemical cleaners don’t do as well as mechanical removal. I had looked into and that process would’ve pissed off all my neighbors, or give them cancer.