Its legit bu only way to clean the valves is to walnut blast them. DI if a big F-UTell them you want to see a pic of the valves before and after the "decarbonization". Ask them if its a maintenance requirement. Its not

 

DELETED

 

way too early IMHO. I'd do it every 3 yrs / 60 000 km at most.

 

Totally agree, I did my first one at about 58,000 miles and there was a moderate amount of carbonization at that point. Getting ready to do one again now as I approach 80,000 miles and I'll borescope again and see how much build up there's been since after I did the first one.

 

I assume they’re just running some kind of cleaner through the intake?

I’m a little skeptical, but would probably give it a try if it’s not too expensive. Every 15,000 miles for this seems reasonable to me. If you keep on top of it like that, it’s more of a preventative thing.

FWIW, my last car (not a Subaru) had bad carbon build up after only 50,000 km. Only way to clean that was removing the intake and physically scraping off the carbon (I did it myself a couple times with solvent and picks/scrapers, but walnut blasting works too.)

Maybe if I’d run some cleaner through there every 20,000 km or so the buildup wouldn’t have gotten so bad? Maybe I could have delayed needing to go in there and do all the scraping work?

 

You can buy the actual intake cleaning kit that Subaru uses and sells through their parts department for $35. It's not real hard to do and you'll avoid the ridiculous costs that they want at the dealership. Did it on my Crosstrek at 70,000 miles and it actually did a very good job!

 

There's a thread or three about our direct injection systems having an unexpected flaw of intake valves collecting/depositing egr byproducts because injectors are configured directly into each cylinder head. Conventional fuel injection systems helped intake valves from building up deposits by spraying fuel before intake valves. The fine mist tends to wash off fresh egr byproducts, minimizing buildup. Direct injection begat a valve cleaning method of spraying walnut shells onto intake valves to remove hardened deposits. If not done, buildup accrues until unusual engine running occurs from valves not seating, allowing compression to drop, fuel economy drops and lowering overall engine power. This can occur slowly after tens of thousands of miles, as reported by members discovering this phenomenon. 'Sandblasting' may be the only way to keep direct injection engines from fouling up.

I'm new to direct injection and somewhat concerned but not enough to fall for dealer fear mongering. Nevertheless, dealers and indy shops are aware of another money maker for business. If I wanted to go geek, I'd buy an inexpensive borescope connecting to a phone or laptop to look inside the intake manifold and valves for a diy inspection. Borescopes are used in industry for decades and were costly until miniaturization of electronics, cameras and led lighting created a very inexpensive borescope anyone can use. I wouldn't be surprised if dealers and repair shops already use them.

 

There's a thread or three about our direct injection systems having an unexpected flaw of intake valves collecting/depositing egr byproducts because injectors are configured directly into each cylinder head. Conventional fuel injection systems helped intake valves from building up deposits by spraying fuel before intake valves. The fine mist tends to wash off fresh egr byproducts, minimizing buildup. Direct injection begat a valve cleaning method of spraying walnut shells onto intake valves to remove hardened deposits. If not done, buildup accrues until unusual engine running occurs from valves not seating, allowing compression to drop, fuel economy drops and lowering overall engine power. This can occur slowly after tens of thousands of miles, as reported by members discovering this phenomenon. 'Sandblasting' may be the only way to keep direct injection engines from fouling up.

I'm new to direct injection and somewhat concerned but not enough to fall for dealer fear mongering. Nevertheless, dealers and indy shops are aware of another money maker for business. If I wanted to go geek, I'd buy an inexpensive borescope connecting to a phone or laptop to look inside the intake manifold and valves for a diy inspection. Borescopes are used in industry for decades and were costly until miniaturization of electronics, cameras and led lighting created a very inexpensive borescope anyone can use. I wouldn't be surprised if dealers and repair shops already use them.

I would speak surprised to find any dealership or independent mechanic that doesn't have a borescope in their toolkit nowadays. I bought a really simple one on Amazon a few years ago that plugs right into my smart phone and for the price of about $30 actually works very well.

 

It's likely walnut blasting or intake valve cleaning. "running a cleaner through" won't do squat since fuel does not contact intake valves in DI engines.
The borescope idea was also discussed in the thread below. the TGV blocks the access, unfortunately.

https://www.subaruxvforum.com/threads/just-did-intake-valve-cleaning.182279

 

The cleaning kit I used does reach the intake valves because you actually inject it directly into the intake airway. It did a very good job and it was the very low cost kit right from Subaru parts department. I do agree that any of the so-called cleaning products such as Seafoam or Berryman poured into the gas tank will not work at all, the cleaner has to be injected into the intake tunnel.

 

It's likely walnut blasting or intake valve cleaning. "running a cleaner through" won't do squat since fuel does not contact intake valves in DI engines.
The borescope idea was also discussed in the thread below. the TGV blocks the access, unfortunately.

https://www.subaruxvforum.com/threads/just-did-intake-valve-cleaning.182279

You are correct that fuel doesn’t contact the top of the intake valves. That’s the whole problem with DI.

But a cleaner would be piped in through the intake, so yes it would contact the back of the valves and possibly be of some benefit.

 

Run the cleaner through a vacuum line.

 

Meh. Chevron Techron concentrate, a bottle a year, in the petrol tank is your friend(@ $9 per- Walmart or the like). I've found this really keeps the detonation quality high and the car running smooth.

 

This does nothing for carbonization on DI engines

 

It's a scam at that mileage. Check your user manual and you won't see it listed on the maintenance schedule.

I would question anything else that they recommend if they're willing to try something so silly. I bet they sell nitrogen for tires and blinker fluid.

 

I bet they sell nitrogen for tires and blinker fluid.

What's wrong with organic free-range blinker fluid?

 

From subaruoutback.org forums; https://www.subaruoutback.org/threa...ack.org/threads/direct-injection-carbon-buildup-and-oil-dilution.501589/page-12. In the thread, a link to subaruforester.org image; https://www.subaruforester.org/attachments/image1-jpg.500279/

 

They are just stealing your money. Buy Top Tier gas and don't worry about it.

 

it is good to prevent build up especially when you dont install catch can. However, the best is to get the picture of the valve before and after treatment. Sounds a bit early for subaru, but personally I believe this protocol ia better because my experience besides walnut blasting that takes half day downtime, to run cleaner through intake is best done after 1 fuel system cleaner treatment in tank and followed by another one after running cleaner through intake. After 60k miles it is also recommend to clean your catalytics converter to maintain the fuel economy.

 

it is good to prevent build up especially when you dont install catch can. However, the best is to get the picture of the valve before and after treatment. Sounds a bit early for subaru, but personally I believe this protocol ia better because my experience besides walnut blasting that takes half day downtime, to run cleaner through intake is best done after 1 fuel system cleaner treatment in tank and followed by another eoene after running cleaner through intake. After 60k miles it is also recommend to clean your catalytics converter to maintain the fuel economy.

A catch can is a dubious investment at best. There are dozens of Youtubes that show the intake valve cleaning does much. Having said that, I have done it 5 times on my 2018XT. I will do the walnut blasting at 55K miles.

 

Somewhere in my Subaru service travels I found "Your Severe Maintenace Schedule: 2024 Subaru Crosstrek Wilderness" which is for 300k miles.
It never says "decarbonize" anything. Change the engine oil and filter and engine air cleaner often.
If Subaru doesn't say to do it, it isn't going to happen. I have the 80k mile extended Service Plan, only going to do what it says, nothing more, nothing less.
Not going to give them the chance to deny coverage because I did or didn't do something.
I also have pages 28 and 29 out of the "WARRANTY & MAINTENANCE 2024" booklet that came with my Subaru. Doesn't say anything about decarbonizing anything.
Page 43 of the "Getting Started Guide Crosstrek 2024" has the "FUEL SPECIFICATIONS AND CAPACITY". Doesn't say anything about using "Top Tier" fuel, but that is what we get in the State I live in.

 

I agree with you!

 

Subaru does sell their own intake cleaner, so it’s not like they don’t recommend the procedure.

SOA868V9160 - Top Engine Cleaner - Genuine Subaru Part

Genuine Subaru Part # SOA868V9160 - Top Engine Cleaner

parts.subaru.com

The question is whether you want to do it proactively as part of regular maintenance, or wait until the buildup is so bad you have drivability issues.

 

I have 335k miles on my fuel injected Oldsmobile 3800 Series II engine. It is my daily driver. Original fuel injectors and throttle body. Never used any kind of cleaner. Still runs good.
If my Subaru throws a CEL code I will let my Warranty or Extended Warranty deal with it.
Have a bad feeling it is going to cost me a lot of money just to do the prescribed severe service maintenance mandated by Subaru. I am pretty sure they are going to call driving off road Severe Service.
If my Service Advisor wants to do it for gratis, that is fine.

 

Maybe I'm "old school" but this sounds like a scam. I was always taught to take the car out on the freeway for a good burn. If you're making a lot of stop & go drives and for short distances it's always good to take her out at high speeds for a bit to burn off the carbon buildup.
Is that not the case any more?🙄

 

Nope! Older cars did benefit from the ol ‘Italian tuneup’ but it’s not that way anymore

 

I have 335k miles on my fuel injected Oldsmobile 3800 Series II engine. It is my daily driver. Original fuel injectors and throttle body. Never used any kind of cleaner. Still runs good.
If my Subaru throws a CEL code I will let my Warranty or Extended Warranty deal with it.
Have a bad feeling it is going to cost me a lot of money just to do the prescribed severe service maintenance mandated by Subaru. I am pretty sure they are going to call driving off road Severe Service.
If my Service Advisor wants to do it for gratis, that is fine.

Your Olds 3800 is not Direct Injection. Modern DI engines are a completely different kettle of fish.

Maybe I'm "old school" but this sounds like a scam. I was always taught to take the car out on the freeway for a good burn. If you're making a lot of stop & go drives and for short distances it's always good to take her out at high speeds for a bit to burn off the carbon buildup.
Is that not the case any more?🙄

Nope. Direct Injection has changed all that.

 

Your Olds 3800 is not Direct Injection. Modern DI engines are a completely different kettle of fish.



Nope. Direct Injection has changed all that.

^^THIS

 

Did not know. Another 21st Century "advancement". Like I need ESS to tell me when I need to turn the engine OFF to save gas. I know which lights are "forever".
I want to "drive" my Wilderness, Don't want it "driving" me.
Somehow I never got into the 21st Century.
Now that I am out of "break-in" I regularly hit 4k RPM going up steep hills on the Interstate. That and Top Tier gas should keep the intake system really clean.
End of rant.

 

Did not know. Another 21st Century "advancement". Like I need *** to tell me when I need to turn the engine OFF to save gas. I know which lights are "forever".
I want to "drive" my Wilderness, Don't want it "driving" me.
Somehow I never got into the 21st Century.
Now that I am out of "break-in" I regularly hit 4k RPM going up steep hills on the Interstate. That and Top Tier gas should keep the intake system really clean.
End of rant.

Unfortunately, direct injection has one indirect problem; exhaust gas recirculation/combustion blowby gases are fed back into the intake air manifold where it collects onto the interior passageways and intake valves. Injectors outside cylinders helped minimize buildup by spraying fuel in front of intake valves to help wash away the effects of egr. Direct injection places injectors next to spark plugs, spraying fuel directly into cylinders, allowing egr deposits to buildup on intake valves. Subaru downplays this phenomenon with zero mention in owner's manuals but willingly offer valve cleaning services for a fee. The two links I posted in a previous reply can help explain and show the effects of direct injection. DI in and of itself is another step in emissions control as well as fuel economy. However, the dark side of DI has been exposed. There are always compromises when technology advances. This is one of them.

 

Yup Chevron stations have the techron added to their fuel to help clean the valves.
Btw... that was a pretty good rant.🤣

 

Chevron gas had Techron decades before DI was a thing.

And you guys are still completely missing the point. Nothing you add to the fuel is going to do a damn thing to clean deposits off the top side of the intake valves.

 

That must be the reason for Top Tier gasoline. Guess I need to avoid my cash only el cheapo gas station.
I depend on Forums like this for a "reality check". Try to keep me straight, it is a tough job but somebody needs to do it.

 

After I posted... I checked "techron" online....
Chevron gas has it, but in very small amounts.
If that's the only station you frequent that should be fine. Alternatively you can dump in ( on an empty tank) Redline SI-1 or Gumout ReGane

 

Guess this should work: https://www.napaonline.com/en/p/CHV...2jWnupGK5amX3Gk3ZYORP3vVT4TOSLWl0XvGHC8r69ekpeqKMfU1waAiRHEALw_wcB&gclsrc=aw.ds
Back in the Dark Ages we used Marvel Mystery Oil for everything.

 

Don't forget STP

 

As an olderrrrrr driver, I can understand the confusion over some folks that THINK top tier or Chevron additives would help in this matter. When engines had fuel injectors located at port...sure. The cleaners and higher grade fuel would naturally wash/clean those valve areas.

However, in today's DIRECT injection motors, that port injection is gone (although some have both port and direct), and the injector is now placed PAST the valves and DIRECTLY over the the piston combustion area. So no fuel, AT ALL, passes the valves for natural cleaning. Gotta save those precious fuel droplets

Add the smaller liter, higher pressure, higher temperature, and possible turbo...you have a perfect storm to cake on those deposits faster at the cost of saving fuel

There has YET, I repeat YET, to be a an actual side by side comparison of two identical motors:
One doing the preventative catch can and/or occasional cleaner method to keep carbon buildup at bay. And a second motor that does not have any catch can or cleaner maintenance.
Lots of opinions and skewed posts/theories/etc.

The fact of the matter is all DI engines WILL get enough carbon build up at some point. Some DI vehicles have gone on without any walnut blasting or cleaning and are still chugging along after several (ie 100,200,300k) miles without so much as a hiccup. Some vehicle owners swear they needed the cleaning at 30k miles. A lot is going to depend on your oil change schedule, your driving habits, highway driving, city driving, etc

So lets just say the average DI engine would benefit from a good walnut or harsh chemical/scrubbing at 150,000 miles. What is the catch can and regular intake spray cleaning going to prolong that mileage to? 155,000 miles? 200,000 miles??? No one has yet proved or determined this. Again, only theories...no actual proven facts!

I don't know about you, but I plan to hit the intake with some cleaner like Berryman's, CRC, or Subaru's kit posted above, maybe every 30-50k miles (if I feel the vehicle is lacking in performance). No catch can needed. Just let the deposits form. And...if I still have the car at 150,000 miles and the valves seem to obviously need a good cleaning, then I'll invest in a deep cleaning using the walnut or whatever technique is popular at that time. It's just one of those maintenance items needed later of owning a DI vehicle. Just like tires, brakes, timing chains/belts, etc. Regular maintenance is needed especially if you plan to keep the car for awhile.

While it is not popular with the environmentally friendly crowd, there are ways to help avoid the recirculation of warm/oily air by letting the PCV (positive crankcase ventilation valve) air out into the atmosphere like vehicles did just a couple decades ago. I am a big proponent of this as the amount of exhaust/air is negligible, and helps the crankcase breath better, let alone prevent the dirty air from re-entering to get caked onto the valves. There are some hurdles to deal with this in today's vehicles, as certain sensors need to be bypassed or tricked to allow for this mod to work properly. Again, you do you.

 

As an olderrrrrr driver, I can understand the confusion over some folks that THINK top tier or Chevron additives would help in this matter. When engines had fuel injectors located at port...sure. The cleaners and higher grade fuel would naturally wash/clean those valve areas.

However, in today's DIRECT injection motors, that port injection is gone (although some have both port and direct), and the injector is now placed PAST the valves and DIRECTLY over the the piston combustion area. So no fuel, AT ALL, passes the valves for natural cleaning. Gotta save those precious fuel droplets

Add the smaller liter, higher pressure, higher temperature, and possible turbo...you have a perfect storm to cake on those deposits faster at the cost of saving fuel

There has YET, I repeat YET, to be a an actual side by side comparison of two identical motors:
One doing the preventative catch can and/or occasional cleaner method to keep carbon buildup at bay. And a second motor that does not have any catch can or cleaner maintenance.
Lots of opinions and skewed posts/theories/etc.

The fact of the matter is all DI engines WILL get enough carbon build up at some point. Some DI vehicles have gone on without any walnut blasting or cleaning and are still chugging along after several (ie 100,200,300k) miles without so much as a hiccup. Some vehicle owners swear they needed the cleaning at 30k miles. A lot is going to depend on your oil change schedule, your driving habits, high driving, city driving, etc

So lets just say the average DI engine would benefit from a good walnut or harsh chemical/scrubbing at 150,000 miles. What is the catch can and regular intake spray cleaning going to prolong that mileage to? 155,000 miles? 200,000 miles??? No one has yet proved or determined this. Again, only theories...no actual proven facts!

I don't know about you, but I plan to hit the intake with some cleaner like Berryman's, CRC, or Subaru's kit posted above, maybe every 30-50k miles (if I feel the vehicle is lacking in performance). No catch can needed. Just let the deposits form. And...if I still have the car at 150,000 miles and the valves seem to obviously need a good cleaning, then I'll invest in a deep cleaning using the walnut or whatever technique is popular at that time. It's just one of those maintenance items needed later of owning a DI vehicle. Just like tires, brakes, timing chains/belts, etc. Regular maintenance is needed especially if you plan to keep the car for awhile.

While it is not popular with the environmentally friendly crowd, there are ways to help avoid the recirculation of warm/oily air by letting the PCV (positive crankcase ventilation valve) air out into the atmosphere like vehicles did just a couple decades ago. I am a big proponent of this as the amount of exhaust/air is negligible, and helps the crankcase breath better, let alone prevent the dirty air from re-entering to get caked onto the valves. There are some hurdles to deal with this in today's vehicles, as certain sensors need to be bypassed or tricked to allow for this mod to work properly. Again, you do you.

Excellent post 📫 👏

 

That is a great reply. What is the 'deal' with the 'catch can'??? I vaguely remember SCCA sports cars used them. Thought the crankcase fumes went into the intake air cleaner?
I use Amsoil Signature oil because it has minimal oil fume evaporation. That should solve that problem, I hope.
If I can get 8 good years out of this Subaru I will be happy. By then I will probably be too old to go off road. I'll be "arm chair" wheeling by then.

 

That's another "literally" can of worms topic like oil or anything else.

Honestly, IMO, and it's just my opinion, if you drive your CT for 10 years/100,000 miles, you should not have any major engine or CVT issues. But that's assuming regualr driving and no racing or 4 wheeling This is also my first subie and it seems to be on par with most JDM of late. All of today's vehicles, IMO, should make it to 100,000 with very little issue. It's after that, when most vehicles need any major work, including the JDM. So I think you should be good. Again, my first soob as well, but I knew toyota partnered with Subaru, so that made my decision a bit easier as far as longevity/reliability. Honestly, its a crap shoot these days.

 

Took me 28 years to put 326k on my Oldsmobile. 10 more years on my Subaru works for me.
Thanks for your opinions, I need all the help I can get.

 

I loved Oldsmobiles , they are sorely missed 😢