Question about Skyactiv 2.5L Engine

[EliNY]

Hello,

I am about ready to purchase a new vehicle, and one of the three vehicles that I have narrowed down my choice to is the CX-5. However, I have been doing a lot of reading on this forum and on the Internet about the GDI engine and carbon buildup. I spoke to a service technician about this at my local Mazda dealership… Which only made me feel more concerned, as he mentioned that he has seen some Mazdas with as few as 40,000 miles with the engine destroyed because of carbon buildup.
I really like the CX-5, And would love to purchase it. However, I would like to hear about how some of you who own a CX-5 have dealt with the carbon buildup… Or perhaps have prevented it from occurring. I drive 18,000 to 20.000 miles per year… In all kinds of driving conditions from highway to city and everything in between. With that said, I do not want to purchase a car which will need a new engine with a couple of years.
That is why I decided to write this… To get input from other CX-5 owners and see how you deal with it. Is this some thing that I should consider a dealbreaker?
Thank you in advance for your responses.

 

[HyFlyer]

... I spoke to a service technician about this at my local Mazda dealership… Which only made me feel more concerned, as he mentioned that he has seen some Mazdas with as few as 40,000 miles with the engine destroyed because of carbon buildup. ...

I'm no Mazda tech, but I find his comment inconsistent with reality and maybe more in line with being able to get you into engine carbon cleaning at dealer rates.

Yes, GDI engines do indeed get carbon buildup on the back of intake valves and intake but I think it's closer to 150k - 200k miles before it causes concerns.

We have several Mazda's in the family with a Mazda3 pushing 180k miles and a cx5 with 175k miles and no carbon cleaning or issues. (I will be looking into carbon cleaning for both of them probably later this year.

I wouldn't worry about carbon build up. It's not a big issue.

 

[ruthrj]

I agree with HyFlyer, not a big issue. I haven’t heard a single report here of an engine being “destroyed” due to carbon on the intake valves. I myself experienced some symptoms of buildup on the intake valves around 65k miles on my 2L ‘13. It was a slightly rough idle and I felt what I believed was a misfire while waiting at a drive thru. I cleaned the valves myself and never had another issue.

The problem? Frequent short trips for the first several years of the vehicles life. After moving to northern Alabama I’ve driven nothing but hilly terrain and highways. Never had another problem with that ‘13 up to 120k miles before it was totaled.

Mazdas SkyActiv is engineered to get the intake temperature at the valves high enough to prevent issues for most people. Frequent short trips are no bueno, but mix it up and you’ll be just fine. And if you do get a carbon issue with tens of thousands of miles? Clean the intake valves and you’re as good as new.

This isn’t limited to just Mazda. Many engines are now direct injection from many different manufacturers. Better mileage and power output with the potential consequence of carbon buildup on the intake valves. Toyota does have a different system with both port and direct injection (something I do like on my ‘21 hybrid RAV4), but this isn’t an issue that prevented me from replacing the ‘13 2 liter CX-5 with a ‘23 CX-5 2.5T.

 

[yrwei52]

I am about ready to purchase a new vehicle, and one of the three vehicles that I have narrowed down my choice to is the CX-5.

Mind to tell us what is your current vehicle driving with how many miles? And what are the other 2 vehicles you’re considering?

I have narrowed down my choice to is the CX-5. However, I have been doing a lot of reading on this forum and on the Internet about the GDI engine and carbon buildup.

If you’ve been doing a lot of reading on this forum and the Internet about the GDI engine and carbon buildup, you should know not just the Mazda SkyActiv-G 2.5L, almost all engines in a new vehicle are in GDI form and they will have carbon buildup issue on intake valves even if you keep using Top Tier gasoline with better detergent. So it’s inevitable that for any car you choose most likely you’ll have carbon buildup issue. Toyota’s current Dynamic Force 2.0L / 2.5L I4 with dual port / direct fuel injections could be the only exception if you keep using the Top Tier gas with better detergent.

I spoke to a service technician about this at my local Mazda dealership… Which only made me feel more concerned, as he mentioned that he has seen some Mazdas with as few as 40,000 miles with the engine destroyed because of carbon buildup.

Wow, I’d like to talk to this Mazda tech in person as his words definitely are a big exaggeration! I’ve never heard an engine got “destroyed” by the carbon buildup! Yes carbon buildup will hurt engine performance and efficiency. A severe carbon buildup could make engine running harsh or even difficult to start, but it isn’t going to destroy the engine! You only need to clean up the carbon deposit in affected areas, and the engine will be running fine like before.

I really like the CX-5, And would love to purchase it. However, I would like to hear about how some of you who own a CX-5 have dealt with the carbon buildup… Or perhaps have prevented it from occurring. I drive 18,000 to 20.000 miles per year… In all kinds of driving conditions from highway to city and everything in between. With that said, I do not want to purchase a car which will need a new engine with a couple of years.

For 2024 Mazda CX-5 it comes with 2 engines, the 2.5L NA with cylinder deactivation (although some may come without cylinder deactivation due to parts shortage), and the 2.5T turbo. IMO, you should be worried about the small possibility of cracked cylinder head on the 2.5L NA with CD if you prefer a non-turbo engine.

That is why I decided to write this… To get input from other CX-5 owners and see how you deal with it. Is this some thing that I should consider a dealbreaker?
Thank you in advance for your responses.

Carbon buildup is an issue you shouldn’t be concerned, but cracked cylinder head is.

 

[yrwei52]

⋯ Toyota does have a different system with both port and direct injection (something I do like on my ‘21 hybrid RAV4)

Almost forgot Toyota does have dual port / direct fuel injection system on its current Dynamic Force 2.0L / 2.5L which should prevent carbon buildup more effectively if you keep using Top Tier gasoline. Or just use Chevron Techron Fuel System Cleaner or something similar to clean up the carbon buildup on intake valves and fuel injectors easily.

 

[EliNY]

I'm no Mazda tech, but I find his comment inconsistent with reality and maybe more in line with being able to get you into engine carbon cleaning at dealer rates.

Yes, GDI engines do indeed get carbon buildup on the back of intake valves and intake but I think it's closer to 150k - 200k miles before it causes concerns.

We have several Mazda's in the family with a Mazda3 pushing 180k miles and a cx5 with 175k miles and no carbon cleaning or issues. (I will be looking into carbon cleaning for both of them probably later this year.

I wouldn't worry about carbon build up. It's not a big issue.

Thank you for your comment.

 

[Snorting2.5]

the concerns about carbon buildup on these vehicles is essentially non-existent.

 

[N7turbo]

he mentioned that he has seen some Mazdas with as few as 40,000 miles with the engine destroyed because of carbon buildup.

Agree with above comments. Absolutely no way can this be a true statement. For carbon buildup to render an engine inoperable, it would take hundreds of thousands of miles.

 

[EliNY]

Mind to tell us what is your current vehicle driving with how many miles? And what are the other 2 vehicles you’re considering?



If you’ve been doing a lot of reading on this forum and the Internet about the GDI engine and carbon buildup, you should know not just the Mazda SkyActiv-G 2.5L, almost all engines in a new vehicle are in GDI form and they will have carbon buildup issue on intake valves even if you keep using Top Tier gasoline with better detergent. So it’s inevitable that for any car you choose most likely you’ll have carbon buildup issue. Toyota’s current Dynamic Force 2.0L / 2.5L I4 with dual port / direct fuel injections could be the only exception if you keep using the Top Tier gas with better detergent.



Wow, I’d like to talk to this Mazda tech in person as his words definitely are a big exaggeration! I’ve never heard an engine got “destroyed” by the carbon buildup! Yes carbon buildup will hurt engine performance and efficiency. A severe carbon buildup could make engine running harsh or even difficult to start, but it isn’t going to destroy the engine! You only need to clean up the carbon deposit in affected areas, and the engine will be running fine like before.



For 2024 Mazda CX-5 it comes with 2 engines, the 2.5L NA with cylinder deactivation (although some may come without cylinder deactivation due to parts shortage), and the 2.5T turbo. IMO, you should be worried about the small possibility of cracked cylinder head on the 2.5L NA with CD if you prefer a non-turbo engine.


Carbon buildup is an issue you shouldn’t be concerned, but cracked cylinder head is.

Thank you for your response. I currently drive a 2012 Honda Accord with 244K miles…never any major problems…but car converter is starting to go.
Other 2 vehicles I am considering are Honda HRV and Toyota Corolla Cross…neither one is GDI…or rather GDI only. HRV is port injection, and as you already mentioned, the Corolla Cross is both Direct and Port Injection. But they are both CVTs…which I am not happy about.
I am looking at the base/Select trim, and was told during test drive that this trim does not have cylinder deactivation, which I am actually happy about.
What is the deal with the cracked cylinder heads?

 

[CarpeDiem]

Maybe a few facts (see below) instead of opinion are in order. It is possible for serious carbon buildup to occur in under 40,000 miles, where it can interfere with the valves closing fully or cause jammed piston rings. Would this "destroy" an engine? Probably not, but it could make it far less efficient.

This is true for any direct injection engine, but Mazda seems to have minimized the effects. Remember that direct injection has been used in internal combustion engines for over a century with billions of driven miles - if it was so terrible it would not still be so common. (BTW, the long-term use mentioned above has been in diesel engines.)

I would not be so concerned about carbon buildup in Skyactiv engines. I'd buy with confidence if you like Mazdas.

Carbon Buildup

 

[yrwei52]

the concerns about carbon buildup on these vehicles is essentially non-existent.

Not true. See post #3 above:

⋯ I myself experienced some symptoms of buildup on the intake valves around 65k miles on my 2L ‘13. It was a slightly rough idle and I felt what I believed was a misfire while waiting at a drive thru. I cleaned the valves myself and never had another issue.

And this member / YouTuber @felixd showed you how much carbon deposit you could get on intake valves from his 2013 CX-5 with only 28,900 km / 18,063 miles:

Video Cleaning Intake valves CX 5 Skyactiv Gasoline engine

 

[Snorting2.5]

Agree with above comments. Absolutely no way can this be a true statement. For carbon buildup to render an engine inoperable, it would take hundreds of thousands of miles.

I don't think any amount of mileage could cause enough build up on a normally maintained Skyactiv. The valves are kept clean using intentionally higher temps on the intake side.

 

[yrwei52]

Thank you for your response. I currently drive a 2012 Honda Accord with 244K miles…never any major problems…but car converter is starting to go.
Other 2 vehicles I am considering are Honda HRV and Toyota Corolla Cross…neither one is GDI…or rather GDI only. HRV is port injection, and as you already mentioned, the Corolla Cross is both Direct and Port Injection. But they are both CVTs…which I am not happy about.
I am looking at the base/Select trim, and was told during test drive that this trim does not have cylinder deactivation, which I am actually happy about.
What is the deal with the cracked cylinder heads?

Honda used to make great cars. My 1998 Honda CR-V with 192K miles is the most reliable car I’ve ever owned. But I wouldn’t get another new Honda due to their inferior engine and vehicle design concept and recent poor reliability record.

My daughter bought a 2022 Toyota Corolla Hatchback XSE after a year on the waiting list. I drove the car several times and I don’t have any issues including the drive feel on its CVT. It has paddle shifters even though I don’t use it. It’s drastically different from my previous experience on the CVT a few years ago driving a Nissan Altima. Go test drive a Toyota Corolla Cross and see if you can take a CVT from Toyota. I believe if you want a most reliable CVT or turbo, Toyota should be the one to consider.

As for cracked cylinder head, both 2.5L NA with CD and 2.5T from Mazda have suffered this problem with different symptom when Mazda modified the cylinder head from original SkyActiv-G 2.5L. Mazda updated cylinder head and exhaust manifold gasket on the 2.5T since 2021 MY to remedy cracked head problem, but only time will tell if this fix is effective.

2.5 NA Cracked Cylinder Head with Oil leaking...How common is this?

2.5T Engine Coolant Leaking TSB

In addition, Mazda also modified original 6-speed auto to reduce the vibration caused by cylinder deactivation and have to use single lockup clutch in torque converter due to space limitation. Unfortunately this could cause ATF contamination with iron powder due to excessive wearing from the single lockup clutch in the TC.

2017~2024 CX-5 Chirp Noise from Automatic Transaxle on 3-4 upshift - Bulletin 05-005/23

If you can find a new CX-5 without cylinder deactivation, go for it. Don’t believe what the salesman told you, and verify the CD existence by VIN and serial numbers on engine and transmission. The window sticker may also mention “cylinder deactivation” feature on the 2.5L NA.

 

[ruthrj]

I’ve considered using CRC intake and turbo cleaner every 10k miles before anything substantial can build up in my ‘23. However, I really don’t care for small chunks of carbon bouncing around in the engine and waiting for it to blow into the catalytic converter. Add in the turbo and it makes me more nervous. The shape of the intake manifold also isn’t ideal for the CRC treatment as it can pool a lot at the lower bend. I did the treatment a couple of times on my ‘13 with no ill effects but it does pose a risk. It’s a safer bet to clear buildup by removing the manifold IF you ever have issues.

I don’t do short trips, and have a daily uphill drive home where rpm’s can routinely hit 3.5k rpm’s for a couple minutes straight. I figure “don’t fix what ain’t broke”, change the oil regularly every 5k, and use top tier gasoline and I’ll be just fine : )

 

[ceric]

To OP:
I was concerned about carbon buildup initially. After some checking online, videos on youtube, etc. I concluded that, there is some buildup in Skyactiv-G engine, but not enough to cause concerns since Mazda already took measures to minimize it. Very bad for Skyactiv-D, however.
That said, buildup is worse for short drives. If you drive 20k miles per year, you should not worry.
BTW, buildup causes engine to loose power due to incomplete valve closure, not destroying it.... this technician is very special.... I wonder if he can explain it.
Worst case. Clean it with walnut blasting. Some shops offer this service.

I have four Mazdas. '14Mazda3, 16Mazda6, 17CX5, 22CX5. (3 2.5L, 1 2.5T)
None has failed me yet due to this buildup per se.