2.5L NA Cracked Cylinder Head with Oil Leaking

[yrwei52]

BTW it was not fixed - the last minutes of the 3rd video is showing it, and he confirmed it with pain. There're 3 more parts of this story...
So finally, he sent that cylinder head to a local factory (he lives in Ukraine).

So the crack was fixed by the professional welder.

The professional welder at the factory cut out the cracked segment of aluminum and welded the new one. Fixing it that way was cheaper for him ($370) than ordering the new head.

The professional welder knows the proper way to fix the aluminum crack. Not only this’s the much cheaper way to fix the crack on the cylinder head, but also the welder can reinforce the weak area during the process and make the area stronger than the new head.

here are 4th, 5th, and 6th (the final) parts of this story:

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 4, Надежда

Всем привет, сегодня покажу проблему с которой я борюсь. Это треснутая головка блока двигателя Mazda 3 в кузове BP с мотором Skyactiv-G объёмом 2.5Это четвёр...

www.youtube.com

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 5, забрал головку после сварки.

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 6, СЧАСТЬЕ ЕСТЬ!

Всем привет, сегодня покажу проблему с которой я борюсь. Это треснутая головка блока двигателя Mazda 3 в кузове BP с мотором Skyactiv-G объёмом 2.5Это шестая...

www.youtube.com

Thanks for posting!

 

[181962]

BTW it was not fixed - the last minutes of the 3rd video is showing it, and he confirmed it with pain. There're 3 more parts of this story...
So finally, he sent that cylinder head to a local factory (he lives in Ukraine). The professional welder at the factory cut out the cracked segment of aluminum and welded the new one. Fixing it that way was cheaper for him ($370) than ordering the new head.
here are 4th, 5th, and 6th (the final) parts of this story:

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 4, Надежда

Всем привет, сегодня покажу проблему с которой я борюсь. Это треснутая головка блока двигателя Mazda 3 в кузове BP с мотором Skyactiv-G объёмом 2.5Это четвёр...

www.youtube.com

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 5, забрал головку после сварки.

Mazda 3 Skyactiv-G 2.5 Трещина в головке. Часть 6, СЧАСТЬЕ ЕСТЬ!

Всем привет, сегодня покажу проблему с которой я борюсь. Это треснутая головка блока двигателя Mazda 3 в кузове BP с мотором Skyactiv-G объёмом 2.5Это шестая...

www.youtube.com

Was that engine by chance built in Mazda's Russian engine plant (which is now closed)?

 

[yrwei52]

⋯
Otherwise, it's just another vehicle with another oil leak and there are lot of them.

No, the oil leak from a cracked cylinder head is totally different from any other types of oil leak you can imagine. It can be catastrophic losing large amount of oil in a short period of time with engine running as the oil is pressurized in these passages within the cylinder head.

 

[yrwei52]

Was that engine by chance built in Mazda's Russian engine plant (which is now closed)?

Why does this matter? Mazda won’t design a different and inferior cylinder head to be manufactured in a different assembly plant. Go watch that Russian / Ukrainian video and see for yourself how thin the cracked area is with a comparison to other head, and you’ll realize why the head of our 2.5L NA with CD is prone to crack.

 

[181962]

No, the oil leak from a cracked cylinder head is totally different from any other types of oil leak you can imagine. It can be catastrophic losing large amount of oil in a short period of time with engine running as the oil is pressurized in these passages within the cylinder head.

It "can be". But is it? The NHTSA does not deal in "can be" speculations. It deals in instances. If your vehicle catches on fire, that constitutes an instance. By all means, report it. Otherwise it is just a speculation. But if you must, knock yourself out. It's not a big waste of time.

 

[Kedis82ZE8]

I put quick link to investigations on this thread

https://mazdas247.com/forum/t/►►►-nhtsa-mazda-cx-5-tsb-listings-brochures-manuals-◄◄◄.123875915/

Find your model year and link is to the right

 

[181962]

Why does this matter?

Vodka...yes! 19th century novels...absolutely! War crimes...none better! Automobile engines...not on a cold day in hell or Vladivostok.

 

[Jack Rabbit]

If your vehicle catches fire from an oil leak or any other reason you should definitely report that to the NHTSA. Otherwise, it's just another vehicle with another oil leak and there are lot of them.

It "can be". But is it? The NHTSA does not deal in "can be" speculations. It deals in instances. If your vehicle catches on fire, that constitutes an instance. By all means, report it. Otherwise it is just a speculation. But if you must, knock yourself out. It's not a big waste of time.

With your reasoning a nuclear power plant would meltdown before anything was reported.
Ka-Bloom.
Thank the heavens some people aren't in charge of nuclear power.

Whether it's work accidents, vehicle accidents, etc, most of society has moved to near-miss reporting

 

[yrwei52]

It "can be". But is it? The NHTSA does not deal in "can be" speculations. It deals in instances. If your vehicle catches on fire, that constitutes an instance. By all means, report it. Otherwise it is just a speculation. But if you must, knock yourself out. It's not a big waste of time.

Many safety recalls are based on “speculations”.

Just use all recalls on my 2016 CX-5. There’s no actual case of fire during the rear end collision according to Mazda, but NHTSA forced MNAO to issue a safety recall on fuel filler pipe only because a lab found some fuel leak after the CX-5 got rear-ended and flipped ove during a test. Mazda even had to stop the sale of the CX-5 for a couple of weeks in the US until the Mazda came out a solution.

My second recall is to reprogram the passenger-side air bag. Again no incident caused by the poor programming, but only from “speculations”.

My third recall is the rear liftgate struts where most people found the replacement are actually shorter (hence the liftgate when open is lower) and weaker than originals, and more dangerous to hit our head!

My forth recall, although it didn’t apply to my CX-5 as mine had got replaced under new-car warranty already, is on my optional and very expensive LED headlights. This recall is the most unbelievable one to me as the failing LED DRLs have nothing to do with NHTSA approved safety features.

So all recalls on my CX-5 are based on speculations!

 

[Greg_J]

Was that engine by chance built in Mazda's Russian engine plant (which is now closed)?

He mentioned that too...His particular engine & car was built in Japan. But as far as I know all engines Mazda assembles in Japan. Probably it doesn't really matter where the engine is built. The primary problem is that the engine was designed with a technical defect.

 

[181962]

But as far as I know all engines Mazda assembles in Japan.

Mazda manufactures engines at their Changan, China plant, at their Chuburi, Thailand plant, and at their Salamanca, Mexico plant. They also had an engine assembly plant in Vladivostok. Russia until it was shut down in 2022 stemming from Russian war sanctions.

 

[CX5Nut]

Many safety recalls are based on “speculations”.

Just use all recalls on my 2016 CX-5. There’s no actual case of fire during the rear end collision according to Mazda, but NHTSA forced MNAO to issue a safety recall on fuel filler pipe only because a lab found some fuel leak after the CX-5 got rear-ended and flipped ove during a test. Mazda even had to stop the sale of the CX-5 for a couple of weeks in the US until the Mazda came out a solution.

My second recall is to reprogram the passenger-side air bag. Again no incident caused by the poor programming, but only from “speculations”.

My third recall is the rear liftgate struts where most people found the replacement are actually shorter (hence the liftgate when open is lower) and weaker than originals, and more dangerous to hit our head!

My forth recall, although it didn’t apply to my CX-5 as mine had got replaced under new-car warranty already, is on my optional and very expensive LED headlights. This recall is the most unbelievable one to me as the failing LED DRLs have nothing to do with NHTSA approved safety features.

So all recalls on my CX-5 are based on speculations!

100% Correct! That is why it is important, as I posted above, to file a complaint with NHTSA if you have the crack & oil leak.

Report a Safety Problem | NHTSA

File a complaint with NHTSA if you experienced a vehicle, tire, car seat or equipment safety problem that could be a safety defect.

www.nhtsa.gov

 

[wlong01]

Do we know if Mazda has taken corrective action for the heads going forward?

 

[Jack Rabbit]

There are many different threads for the cracked head, whether a turbo or NA CD

This seemed the most applicable thread to post.

For those wondering how frequent this may be...
Average CX-5 sales(both turbo and NA CD models) average about 12,900 per month give or take.

Looking through multiple posts on several mazda forums, reddit, and websites,

There was one post that claimed a service clerk said they were seeing 5 per week(approx. 20 per month) which seems very high. Multiplied by 600 dealerships would be 12,000 repairs per month or a 92% failure rate which seems very high.
I disregarded this figure as either the clerk was unknowledgeable or exaggerating or the poster exaggerated.

However, there were several posts from several different posters that claimed that dealerships told them about 1 to 2 per month which seems very believable. Across 600 dealers, that would be approx. 600 to 1200 per month for a 5% to 9% failure rate with a 7% average failure rate or approx. every 1 in 14 people will have a head failure, some of which may occur outside the warranty period. Of course some dealerships may have less and some may have more. Also, this may become more prevalent over the years as vehicles reach higher (out of warranty) mileage so the average rate of failure could potentially be slightly higher.

<EDIT:> also would like to note that the mazda247 poll of turbo cylinder head engine replacements was 36%. Either the turbos have a higher rate of failure or the forum members is a skewed unique segment or the poll could have been manipulated. Whatever the reason, this info was disregarded as well and also makes the lower 7% figure hold more traction.
<END EDIT>

Granted there is no official posting from Mazda as to failure rate so we must depend on the information that's out there.
As several posters have posted similar information concerning 1 to 2 repairs per month, this seems to be a good representation. Just hope your not the 1 out of of those 14 that have it occur after the warranty expiry.

If true, the 7%(or higher) failure rate sure will drop those consumer report ratings.

Your preference. You can disregard or use this information as you will.

Hope this information is helpful to anyone needs it.

 

[CX5Nut]

Interesting....if it's true, a 7% failure rate is something that Mazda can't sweep under the rug!

 

[Jack Rabbit]

Interesting....if it's true, a 7% failure rate is something that Mazda can't sweep under the rug!

Companies only need to keep stuff quiet long enough. By then, most of the affected engines will be out of warranty.

 

[181962]

Consumer Reports data indicates a failure rate of 1% or less in the Engine-Major and Engine-Minor categories of all CX-5 units produced to date from all causes across all trims and model years since the 2018 model year,. That is a far more reliable figure than any extrapolation from random, dubious and anonymous reports scattered across the internet.

In fact, in the Engine-Major category, the pre-CD 2017 model is rated at 4 out of 5, the same as 2018 and 2019, while the 2020 - 2022 are rated 5 out of 5, all above or well above industry average.

Again, these ratings are blended across all trims, so starting in 2019 the ratings include both turbos and NA. However, the 2021 CX-9 (exclusively turbo) has a 1 out of 5 rating for Engine-Minor and 3 out 5 for Engine-Major while 5 out of 5 for both categories for other years since the introduction of the turbo.

 

[sm1ke]

This is useful information to have if you're mindful of the bubble they're in. Social media and forum polls are helpful because you can find like-minded individuals and hopefully share information and experiences, but they are limited to those who make the effort to join and participate. That's what makes the 2.5T poll interesting, but not exactly accurate by any means - someone who is not having any issues (or isn't aware they are having any issues) is much less likely to join a forum looking for answers, and thus would not respond to the poll. Even further, those who have joined a forum may not have replied to the poll for whatever reason. With that said, the fact that the issue is being reported by different users suggests that the problem could be more common than one-off instances.

Same goes for Consumer Reports. Their survey results depend on their subscribers and whether or not they choose to participate. Some join CR just to get access to the info, not to participate in their surveys. I personally prefer getting data like this from Consumer Reports, because it's a much larger sample size with a better representation of owners who are more likely to participate.

In the end, both are confined to their own bubbles and are not a perfect representation of the actual numbers - only Mazda would have that information, since they know how many vehicles were sold and how many of the same problem is appearing across all of their dealerships.

 

[181962]

Same goes for Consumer Reports. Their survey results depend on their subscribers and whether or not they choose to participate. Some join CR just to get access to the info, not to participate in their surveys. I personally prefer getting data like this from Consumer Reports, because it's a much larger sample size with a better representation of owners who are more likely to participate.

Yes, it is the sample size as well as the methodology. CR gets responses from 300,000 subscribers per year. With Mazda having about 2% of the US market over the last decade or so, that gets you to something in the neighborhood of 6,000 Mazda survey responses per year, a high percentage of which are CX-5 owners. If a particular model and year has a statistically insignificant number of responses CR does not rate it.

I have to say stuff gets said in this forum and elsewhere that I view with a great deal of skepticism. The older I get the less concerned I am with people's motivations and just look at their actions. Why would somebody go on-line and lie about something like the reliability of a vehicle? I don't know and I don't much care, but I do smell some fishy stuff in the reporting.

 

[sm1ke]

I should also note that I'm not saying to pick one or the other, or to disregard one or the other. We should just be looking at the info available from all angles, with consideration from other possible sources of info.