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

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.
Some anecdotal reports have the ring of truth to them--a lot of detail, numerous follow-up posts. Others not so much. The credible reports would certainly be helpful in providing info on the repair procedures, time lines, etc. But they are next to worthless in terms of identifying failure frequency with a model that sells 150,000 units per year, most of which I would presume to be non-turbos.
 
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.

This is correct, Mazda manufactures the CX-5 (in smaller numbers) in several other countries.

The volume production is by far in the Hiroshima and Hofu plants.

The US and Canadian market CX-5 are 100% made in Japan with 95% Japanese parts content.

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The Alabama made CX-50 comes with a Mexico plant engine (except for the Turbo models) and uses a lot more US/Canadian parts.

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Its encouraging that there have not been new posts of people having this issue. Hopefully its a very small % of CX-5's effected. But it would be useful if we knew if there was a common thread for the cars that have this issue.

Like, were those CX5s with the cracked head driven on rough roads? Made in one particular plant? Run in real hot or cold conditions? Driven hard before warm up?
 
Its encouraging that there have not been new posts of people having this issue. Hopefully its a very small % of CX-5's effected. But it would be useful if we knew if there was a common thread for the cars that have this issue.

Like, were those CX5s with the cracked head driven on rough roads? Made in one particular plant? Run in real hot or cold conditions? Driven hard before warm up?
Unfortunately here’s a new report by karlyn004 just yesterday for the cracked cylinder head on a 2.5L NA with CD:

Cracked cylinder head in 2019 Mazda cx5… 26,000 miles on it
 

Like, were those CX5s with the cracked head driven on rough roads?
This definitely can be a case as the TSB for cracked cylinder head on the 2.5T says:

“Cracks may be caused by:
• Deformation of the exhaust manifold during usage causing unexpected force to certain areas of the cylinder head.
• Residual stress generated during production in the cylinder head material may be greater than expected. The

external force from the exhaust system when driving over bumps may cause unexpected force to certain areas of the cylinder head.”
 
Unfortunately here’s a new report by karlyn004 just yesterday for the cracked cylinder head on a 2.5L NA with CD:

Cracked cylinder head in 2019 Mazda cx5… 26,000 miles on it
I have to say that I'm not giving that one much credibility, so far anyway. That bit about the large amount of oil dripping out of the vehicle just doesn't jibe with most of the other reports I've seen on this cracked NA head issue. As you know, when the head cracks and oil starts dripping on the exhaust manifold, the burning oil odor and smoke are immediately apparent. It's hard to imagine anyone driving even a mile or two, once that condition starts happening.

So, how can it be possible for that much oil to exit the head from a crack, in what must have been a relatively short amount of time? And it's particularly difficult to imagine, given that the underbody plastic panel is going to catch and retain most of it, until (some of) the oil has enough time to slowly make its way through the small access panels. But a good portion of the oil would probably just spread out in a thin layer on the panel. So a significant amount of oil on the driveway is the most difficult part of that story for me to believe.

Now that said, I'll concede that it's POSSIBLE this particular one was a section that blew out of head, instead of just the typical crack. I've never read anything like that before, but I suppose it can't be impossible either.

And the other thing about that thread is that the OP quickly answered one question, but has not come back since then. I'm going to reserve judgement until more time goes by, but right now that one is in the doubtful category for me. However, I will edit this post, if that OP comes back and proves that what I wrote here is not correct.
 
I have to say that I'm not giving that one much credibility, so far anyway. That bit about the large amount of oil dripping out of the vehicle just doesn't jibe with most of the other reports I've seen on this cracked NA head issue. As you know, when the head cracks and oil starts dripping on the exhaust manifold, the burning oil odor and smoke are immediately apparent. It's hard to imagine anyone driving even a mile or two, once that condition starts happening.

So, how can it be possible for that much oil to exit the head from a crack, in what must have been a relatively short amount of time? And it's particularly difficult to imagine, given that the underbody plastic panel is going to catch and retain most of it, until (some of) the oil has enough time to slowly make its way through the small access panels. But a good portion of the oil would probably just spread out in a thin layer on the panel. So a significant amount of oil on the driveway is the most difficult part of that story for me to believe.

Now that said, I'll concede that it's POSSIBLE this particular one was a section that blew out of head, instead of just the typical crack. I've never read anything like that before, but I suppose it can't be impossible either.

And the other thing about that thread is that the OP quickly answered one question, but has not come back since then. I'm going to reserve judgement until more time goes by, but right now that one is in the doubtful category for me. However, I will edit this post, if that OP comes back and proves that what I wrote here is not correct.

I think you're right to be cautious. I am as well, for the same reasons.

I would like to believe that people wouldn't make stuff like this up, but I have unfortunately been proven wrong recently by one of our own members.
 
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I would like to believe that people wouldn't make stuff like this up, but I have unfortunately been proven wrong recently by one of our own members.
Yes, that's certainly not something we're going to forget anytime soon.

And one thing I've always felt is likely happening on any of these forums is things being made up by competitors - specifically in this case other auto makers or dealers. I have no idea how much of that actually takes place, but OTOH a competitor has everything to gain and nothing to lose by trashing their rivals on these forums.

And that's why the follow up posting is always so important to me, on any problem being reported. The scammers might be able to write a few decent-sounding sentences to describe a problem. However, they typically become exposed if they try to answer specific questions, because they almost never are able to come up with the same thing that an actual owner who is having the problem would write. And that's why they rarely try to follow up, because they know they can't.
 
I think you're right to be cautious. I am as well, for the same reasons.

I would like to believe that people wouldn't make stuff like this up, but I have unfortunately been proven wrong recently by one of our own members.

Need a "pics or it didn't happen" advisory.

 
Anyone can create an account in about a minute.

If they provide a picture, problem solved. Anyone with a CX-5 owns a smartphone.
 
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Need a "pics or it didn't happen" advisory.

Have you seen the video from Ukraine speaking in Russian? Here’s the proof on video and see for yourself. The cracked area on the cylinder head from his 2.5L NA with CD is only 2 mm thin! It’s this video convinced me that Mazda revised the cylinder head poorly to accommodate the cylinder deactivation system added in 2018 MY. No wonder that area is weak and prone to crack.


Mazda 3 Skyactiv-G 2.5 N/A with C/D (2019 year 20.000 km.) - really interesting and detailed process of removing the head and welding the crack. He is speaking Russian but everything is clear without a verbal explanation:

 
Guess I spoke too soon! What I do now is routinely run my hand behind the engine looking for oil especially after a long trip.

Bad news is my powertrain warrantee expires this summer!
If I have a 2.5L NA with CD, I’d also turn off the sound system and listen to the engine each time I start the car in the morning. If there’s any tapping noise from the engine during idling, the switchable hydraulic lash adjusters are failing.

CX-5 engine rattle

2018 CX-5 GT Ticking

From the 2nd link we can see a Service Alert and a TSB related to this issue. Unfortunately Mazda indicated that they have redesigned switchable HLAs for cylinder activation for newer MYs which means those HLAs in earlier day are having issues. Nevertheless this’s another expensive repair if there’s no warranty to cover it.


You should ask your dealer's service department if they intend to replace the 8 switchable HLAs with the redesigned part versions, or if they intend to just swap the ones from the cracked head to the new one. I'm not going to write a long-winded explanation of what that's all about, but will just say it's something that could very well become another significant repair in the future, if they install the old HLAs instead of the redesigned ones.

If you ask the question and they say it's going to be a swap of the old HLAs, then post back for a suggestion on how to perhaps get them to change their plan for that.
 
Anyone can create an account in about a minute.

If they provide a picture, problem solved. Anyone with a CX-5 owns a smartphone.

Very true. Posting a picture is certainly easy enough, but I'm not sure that it would be a good idea to make it a requirement or even enforce it. Probably a good idea to request it in the future though, and if they refuse to provide, well, we can take it for what it is.
 
Have you seen the video from Ukraine speaking in Russian? Here’s the proof on video and see for yourself. The cracked area on the cylinder head from his 2.5L NA with CD is only 2 mm thin! It’s this video convinced me that Mazda revised the cylinder head poorly to accommodate the cylinder deactivation system added in 2018 MY. No wonder that area is weak and prone to crack.

We don't really need "proof", the TSB and that video show and describe the potential point of failure quite well. At this point, it's not a matter of what the problem is, it's a matter of how prevalent it is. So, when someone comes on here with a brand new account stating that their engine is leaking, it makes sense to want to see some proof of that leaking engine. Again, users have shown the lengths they will go to just to get others to believe them, creating fake accounts and making up stories.
 
We don't really need "proof", the TSB and that video show and describe the potential point of failure quite well. At this point, it's not a matter of what the problem is, it's a matter of how prevalent it is. So, when someone comes on here with a brand new account stating that their engine is leaking, it makes sense to want to see some proof of that leaking engine. Again, users have shown the lengths they will go to just to get others to believe them, creating fake accounts and making up stories.
That cautionary tale of the dude with the phony duplicate account should not be some kind of revelation or cause for heightened skepticism or vigilance--skepticism and vigilance should already be the order of the day. It's not like that guy's posts were the first to smell fishy even the ones under his original name.

Every corner of the internet is cluttered with trolls, phony accounts, fake news, as if that has to be said. There's no reason to believe that this forum is any different nor is there any reason to believe the party in question is the first to make up a story about a cracked cylinder head or anything else.

While motivations are difficult to assess, I would venture a guess that fake tales of woe in forums like these are fabricated in the vain hope of getting the manufacturer to take some action, in this case it seems a recall or extended warranty was the objective. The manufacturer has a good idea of the frequency being the provider of parts. Complaints on forums add no intelligence. As you noted, frequency of an issue is what matters because that is what determines the odds an owner will have the same issue.
 
....! What I do now is routinely run my hand behind the engine looking for oil especially after a long trip. ....
If you want to do a good examination of the area of the head where most of the failures have been reported, it's not a difficult thing to do for just about any DIYer.

All that's required is to remove the 5 bolts securing the top manifold heat shield, after first removing the adjacent heat shield covering some of the plumbing at the firewall. It might be possible to free up the manifold heat shield without removing the other shield, however it's a MUCH easier job with that one out of the way.

Once the manifold shield is free to move, there are two possible choices from there. The first is to undo the O2 sensor connector, which will allow the shield to be cleared away from the head. The other choice is to leave the sensor connected, and just lift and push the shield back from the head by half a foot or so. I've found that second method provides enough working room for everything I want to do. Others however may find the working space too constrained, and would prefer the shield be completely removed. But in either case, the O2 wires need to be unclipped from the 2 standoffs.

Once the shield is out of the way. then it simply becomes a matter of using some combination of inspection camera, mirror, cell phone or other camera, to carefully inspect that entire section of the head. I prefer to kneel on the solid parts on top of the engine to get better access for much of this work, however folks who are tall can probably do everything from a standing position.
 
If you want to do a good examination of the area of the head where most of the failures have been reported, it's not a difficult thing to do for just about any DIYer.

All that's required is to remove the 5 bolts securing the top manifold heat shield, after first removing the adjacent heat shield covering some of the plumbing at the firewall. It might be possible to free up the manifold heat shield without removing the other shield, however it's a MUCH easier job with that one out of the way.

Once the manifold shield is free to move, there are two possible choices from there. The first is to undo the O2 sensor connector, which will allow the shield to be cleared away from the head. The other choice is to leave the sensor connected, and just lift and push the shield back from the head by half a foot or so. I've found that second method provides enough working room for everything I want to do. Others however may find the working space too constrained, and would prefer the shield be completely removed. But in either case, the O2 wires need to be unclipped from the 2 standoffs.

Once the shield is out of the way. then it simply becomes a matter of using some combination of inspection camera, mirror, cell phone or other camera, to carefully inspect that entire section of the head. I prefer to kneel on the solid parts on top of the engine to get better access for much of this work, however folks who are tall can probably do everything from a standing position.
Why not just go by the dip stick--no change, no worries.
 
I just finished reading this entire thread. It's very informative.

ADMIN / MODERATOR - Perhaps this thread should be pinned? What do you think? In the spirit of putting a significant issue front and center, it would be helpful/nice/informative if this was pinned.

I'm looking to buy a new 2023 CX-5 NA. However, after researching it (thanks to this forum and several other online resources), I'm deeply concerned about the cracked head problem. Thus, I'm going to start researching other compact SUVs. I'm not sure what I'll find (I may come back to the CX-5... who knows), but at this point I want to be more comfortable before I drop $40,000 on my next car.
 
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