I thought there was but all I can find is a TSB about cracked heads in the 2.5 Turbos resulting in coolant leaks. And, there is a general TSB about how to replace the head if needed in non-turbo CX5s. But nothing addressing the issue of the head cracking and leaking oil. Have I missed it??
Is there a specific TSB for cracked heads in non-turbo CX-5s?
- Thread starter CX5Nut
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- CX5 GT
I dont recall if there is a secific tsb for the cracked heads (non-turbo) oil leaks.
There is a "general one" for the newly redesigned head for all non-turbo until 2021, which kind of relates to the oil leak issue as well.
sample text from the tsb:
Searching Key Words: Cam Journal, Valve Guide, Intake Valve, Exhaust Valve, Valve Spring, Hydraulic Lifter, Coolant leak, Coolant smell, Warp head, Engine Oil Leak, Oil Smell, Oil leak, Misfire, Low Compression, Excessive Leak Down, Burnt Valves, Rocker Arm.
There is a "general one" for the newly redesigned head for all non-turbo until 2021, which kind of relates to the oil leak issue as well.
sample text from the tsb:
Searching Key Words: Cam Journal, Valve Guide, Intake Valve, Exhaust Valve, Valve Spring, Hydraulic Lifter, Coolant leak, Coolant smell, Warp head, Engine Oil Leak, Oil Smell, Oil leak, Misfire, Low Compression, Excessive Leak Down, Burnt Valves, Rocker Arm.
I've never seen anything in print from Mazda indicating that the NA head was redesigned. The write-up in the TSB does say that this new part number represents a loaded head (i.e. including installed valvetrain components), however there is nothing in there about the actual head itself.
Although it might naturally be presumed that the NA head has been redesigned, there's been no proof of that so far, that I'm aware of. And for anyone who insists that the head must have been modified in some way, I've seen multiple references made to 'a batch of bad castings', as being the root cause of the NA cracked heads. I certainly don't know if that's true or not, but if it is then there would presumably have been no need for Mazda to redesign that head.
Regardless of what the actual issue with the head is, this TSB is very unsettling and concerning to me, for one major reason. Why would an automaker take this unusual step of distributing loaded heads to their dealer service departments? The only logical reason I can come up with is that the failure rate must be significant enough to justify that action. If NA cylinder head failures were rare (as is typical with most other newer model vehicles), then why would they ever even have considered doing something like this?
I believe this loaded head enabled Mazda to reduce the number of hours reimbursed to the dealers for warranty head replacements, due to the tech no longer needing to do the time-consuming job of transferring all of the valvetrain components from the damaged head to the new one. And it also eliminates potential mistakes made by the tech doing that transfer work. Just my own theory about that and, like most of this stuff, I'm not expecting to ever have it either confirmed or disproved.
That makes a lot of sense. Mazda would only supply these "loaded heads" if a significant number of heads have had to be replaced, or are expected to fail.
I'm surprised this defect has not resulted in an engine fire yet. Engine exhausts can reach a temp of 1000 F, and motor oil can ignite at 300-400F. From what I understand this crack allows oil to drip onto the exhaust.
I'm surprised this defect has not resulted in an engine fire yet. Engine exhausts can reach a temp of 1000 F, and motor oil can ignite at 300-400F. From what I understand this crack allows oil to drip onto the exhaust.
My daughter's 2019 NA CX-5 powertrain warranty has just recently ended, and I would expect no 'good will' assistance, should her vehicle's head ever crack. I've actually been hoping that one of these cracked NA heads does ignite, provided of course that there are no injuries related to that fire.
A number of the NHTSA cracked NA head reports have mentioned smoke coming from the engine bay, so IMO an actual vehicle fire would be more than enough for them to take out the big hammer and bring it down on Mazda for this issue. Although I don't know exactly how that would play out for us, in the case of the Hyundai/KIA Theta engine debacle, the actions taken by the NHTSA against those automakers forced them to replace hundreds of thousands of engines at N/C under extended warranty, and the total number replaced continues to get higher every day.
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- Plano, Texas, USA
Well said. I wonder if you’ve watched the Russian YouTube video from Ukraine where a Mazda3 owner removed the cracked cylinder head trying to weld the crack on his 2.5L NA with CD?
No...have not! Do you have a link?
I've watched those vids multiple times, trying to make sure I didn't miss anything with the inexact language translation going on there. And yes, I know he did say that this NA head is too thin in key places. However, it's very unlikely that guy is an automobile engineer, so his comment is opinion, based on comparing the Mazda head to other automakers.
Now having said that, I want to make it clear that I'm not trying to claim the NA head has no design issues. I'm not an engineer either, and have no expert opinion to offer on that. My only point here is that Mazda has not said anything about the NA head issues, as they did with the turbo head (and also the defective switchable HLAs).
So until they do so (if they ever do), or a qualified engineer can show proof, we don't know if the head design is defective or if the issue was with the manufacturing process. I'm completely open to either one being possible.
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- Plano, Texas, USA
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- Plano, Texas, USA
I’m more convinced on the bad / weak design by Mazda with 2mm thin wall at the cracked area after watched that video. Remember this head on the 2.5L NA with CD was modified from the original head on SkyActiv-G 2.5L NA without CD. We have never seen ANY reports with cracked head on original head. But once it was modified to accommodate the cylinder deactivation, the crack started happening however how rare it is. Also the cylinder head on the 2.5T was also modified from original head on the 2.5L NA without CD. Now the same cracked head problem started happening too. Another example of a bad design to modify an existing part which is proven reliable.
Although this continues to be interesting from a technical perspective, I really don't dwell on the cause of the problem these days. I consider it to be a horse that's already left the barn.
What I do think about quite a bit is what it will take for Mazda to start covering these NA head replacements for vehicles with expired powertrain warranties. I suspect they'll never do anything voluntarily, so it's probably going to take some level of NHTSA involvement to make anything positive happen for us on this issue. And that means it's going to have to become safety-related in the eyes of the NHTSA, in order for them to take an active role. Beyond that, I have very little faith in class action lawsuits providing much benefit in cases such as this, but wouldn't automatically turn my back on that option either.
