Which Mazda6 to choose to avoid possible cylinder head crack?

[FartInTheWi]

Hi,

I'm currently in the market for mazda 6, I've been reading up on quite a few cases of cylinder head crack, at first I thought it was only for 2.5T's , however there's people saying they have head cracks (in different spots than 2.5T's I believe) on 2.5NA's too. Some say it's because of cylinder deactivation, others say it's a defect from a factory for over-torquing exhaust manifold bolts and so on.

I'll be buying it from US and importing it to europe (it's cheaper that way + I get lower milage car). Therefore if any issue arises with cylinder head crack, I for sure won't be able to ask mazda for help.

I'm looking specifically for 2.5NA (Since for 2.5T 2018-2021 is TSB for cylinder head crack and 2021 has another TSB for valve stems, ugh...), so I'm wondering if anyone knows, which year would be the best to buy, are those cracked heads on 2.5NA frequent or unicorn cases, perhaps mazda fixed it for 2.5NA something for 2021 year as well? (Like they did with 2.5T in that TSB).

Basically should I be worried or just grab any 2.5NA? if no, which year (2018-2021) is best for 6's?

Thank you!

 

[khoney]

Google "TSB 01-002/2023" to read the details concerning this ticking time bomb. But from the TSB:

2019-2020 CX-5 SKYACTIV-G 2.5T vehicles with VINs lower than JM3KF******830243 (produced before Jun. 9, 2020)
2016-2020 CX-9 SKYACTIV-G 2.5T vehicles with VINs lower than JM3TC******422801 (produced before Jun. 9, 2020)
2018-2020 Mazda6 SKYACTIV-G 2.5T vehicles with VINs lower than JM1GL******523967 (produced before Mar. 25,2020)

Mine failed on my CX-9 purchased in June of 2018, at ~82K miles. This is happening on a great many of the affected vehicle ranges, because this is due to a DESIGN FLAW in the cylinder head. They have re-engineered a modified cylinder head and head gasket to supposedly address this issue.

I see you are looking for an N/A not a Turbo, so I wouldn't expect there to be such a widespread problem. I believe the weight of the turbocharger was a contributing factor.

 

[FartInTheWi]

Google "TSB 01-002/2023" to read the details concerning this ticking time bomb. But from the TSB:

2019-2020 CX-5 SKYACTIV-G 2.5T vehicles with VINs lower than JM3KF******830243 (produced before Jun. 9, 2020)
2016-2020 CX-9 SKYACTIV-G 2.5T vehicles with VINs lower than JM3TC******422801 (produced before Jun. 9, 2020)
2018-2020 Mazda6 SKYACTIV-G 2.5T vehicles with VINs lower than JM1GL******523967 (produced before Mar. 25,2020)

Mine failed on my CX-9 purchased in June of 2018, at ~82K miles. This is happening on a great many of the affected vehicle ranges, because this is due to a DESIGN FLAW in the cylinder head. They have re-engineered a modified cylinder head and head gasket to supposedly address this issue.

I see you are looking for an N/A not a Turbo, so I wouldn't expect there to be such a widespread problem. I believe the weight of the turbocharger was a contributing factor.

There's also a TSB for 2.5 N/A for a cylinder head crack, however it cracks in a different place and for a different reason. The 2.5 N/A crack is caused by cylinder deactivation, turbo's don't have that. So basically all 2.5's crack... After a research I've decided to go for M6 after 2020 (supposedly after they fixed the head crack issue), only to be greeted by another TSB for Valve stem seals... Uh... At least this one seems cheaper to fix.

 

[edmaz]

There's also a TSB for 2.5 N/A for a cylinder head crack, however it cracks in a different place and for a different reason. The 2.5 N/A crack is caused by cylinder deactivation, turbo's don't have that. So basically all 2.5's crack... After a research I've decided to go for M6 after 2020 (supposedly after they fixed the head crack issue), only to be greeted by another TSB for Valve stem seals... Uh... At least this one seems cheaper to fix.

NA cracked head is definitely not happening nearly as often on MY 2020 and newer, compared to 2018/2019. And the valve stem seal issue is only on the 2021 Turbo - so far anyway.

 

[sm1ke]

2.5NA non-CD engine is the least likely to have any problems related to cylinder head cracks.

2016-2020 2.5T engines have potential for the head to crack at the exhaust manifold. New head and gasket were designed for 2021+ engines. Some 2021 engines may have valve stem seal issues, but this was supposed to have been fixed for late 2021 and 2022+ models.

2.5NA CD engines have potential for the cylinder head to crack in a different area. The cylinder head design has not been changed for this engine, so the potential for the head to crack in the same spot remains, even if the head is replaced.

 

[edmaz]

2.5NA non-CD engine is the least likely to have any problems related to cylinder head cracks.
.....

I'm not aware of even one non-CD NA head cracking. Not saying it's never happened, just that I've never seen one. And some VERY outstanding news is that there is a non-CD NA option available for MY 2024, in various trims. It's simply the original PY-VPS from gen 1, being made available by Mazda once again. I would jump (actually leap) on this myself if I was currently in the market for a new vehicle.

....
2.5NA CD engines have potential for the cylinder head to crack in a different area. The cylinder head design has not been changed for this engine, so the potential for the head to crack in the same spot remains, even if the head is replaced.

Yes, it appears to be virtually certain that no design change was ever made to the CD head. The standard line from virtually every Mazda tech and other employee that I've seen is that there was a 'run of bad castings' with the early CD heads. SO FAR, the cracked head issue has been very significant on the 2018, quite a bit less on the 2019, and very much less on the 2020 and newer.

The one thing that continues to bother me about the bad castings explanation is that there continues to be at least some CD cracked heads on the later MYs. Given how much this has cost them, I would have expected Mazda to be all over this bad castings business, and that (human) heads would roll if it continued to show up, even in very small numbers. So that part continues to nag at me, and won't let go. I will add however that multiple Mazda techs on the CX-5 FB group have stated that they have never had a vehicle with a replaced cracked head come back with another one. They have also commented that cracked head replacements has slowed down significantly in the past few months or so, which is also good news.

It would be really helpful if Mazda would provide even just a small bit of 'official' information about the NA cracked head problem, but it seems like that's just never going to happen.

 

[FartInTheWi]

I'm not aware of even one non-CD NA head cracking. Not saying it's never happened, just that I've never seen one. And some VERY outstanding news is that there is a non-CD NA option available for MY 2024, in various trims. It's simply the original PY-VPS from gen 1, being made available by Mazda once again. I would jump (actually leap) on this myself if I was currently in the market for a new vehicle.



Yes, it appears to be virtually certain that no design change was ever made to the CD head. The standard line from virtually every Mazda tech and other employee that I've seen is that there was a 'run of bad castings' with the early CD heads. SO FAR, the cracked head issue has been very significant on the 2018, quite a bit less on the 2019, and very much less on the 2020 and newer.

The one thing that continues to bother me about the bad castings explanation is that there continues to be at least some CD cracked heads on the later MYs. Given how much this has cost them, I would have expected Mazda to be all over this bad castings business, and that (human) heads would roll if it continued to show up, even in very small numbers. So that part continues to nag at me, and won't let go. I will add however that multiple Mazda techs on the CX-5 FB group have stated that they have never had a vehicle with a replaced cracked head come back with another one. They have also commented that cracked head replacements has slowed down significantly in the past few months or so, which is also good news.

It would be really helpful if Mazda would provide even just a small bit of 'official' information about the NA cracked head problem, but it seems like that's just never going to happen.

But if they did not change anything in terms of cylinder head design, how can newer one's have less problems? Perhaps there's just less cases of newer models with this failure just because of lower mileage?

 

[edmaz]

But if they did not change anything in terms of cylinder head design, how can newer one's have less problems? Perhaps there's just less cases of newer models with this failure just because of lower mileage?

It's the sentence right before the one you highlighted (bolded).

 

[FartInTheWi]

It's the sentence right before the one you highlighted (bolded).

Ah, my bad.

 

[N7turbo]

Your can read more on this from @edmaz here:

Which trim level for new CX-5?

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