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

[yrwei52]

No, our CX-5 has never overheated. We live in northern New England, so our summers are not especially hot. And the vehicle has never been worked particularly hard.

Cracked cylinder head on Mazda’s SkyActiv-G 2.5L NA with CD and 2.5T has nothing to do with overheating. Even infamous sudden overheating problem on Mazda’s SkyActiv-D 2.2L diesel doesn’t show cracked cylinder head symptom, when the coolant is spraying all over the engine bay!

>> Rampant speculation below <<

I do have one suspicion about what might have contributed to the issue. The TSB mentions that expansion characteristics of the exhaust manifold can put unexpected stress on the cylinder head. I wonder if movement of the exhaust system might also put stress on the head.

Back in July of this year we had a trailer hitch installed on the vehicle, and my mechanic said that to install it he had to disconnect the rear exhaust hanger(s) to drop the muffler out of the way. Given the apparently weak design of these cylinder heads, I wonder if it may have sustained damage during that process.

Last week when the leak started we were hitting mid 20s Fahrenheit overnight and daily high temps in the mid 30s. This was the first cold weather we've had since the hitch was installed. If there were tiny cracks in the head from the exhaust being flexed around, maybe the temperature cycling last week could have caused it to finally fail?

Just a thought. I have no idea whether this contributed at all to the head failure.

/speculation

The TSB you mentioned is only for cracked cylinder head on the 2.5T. Mazda has never issued a TSB for the same problem on the 2.5L NA with CD. But the reason for cracked head on the 2.5L NA with CD could be similar, the head strength got compromised when Mazda modified the cylinder head on 2.5L NA for cylinder deactivation, and for turbo. The 2.5L NA with CD engine tear-down video from Ukraine / Russia posted earlier in this thread has exposed the cracked area with 2 mm thin wall which indicates the weakness of the crack area.

 

[CX5Nut]

Cracked cylinder head on Mazda’s SkyActiv-G 2.5L NA with CD and 2.5T has nothing to do with overheating. Even infamous sudden overheating problem on Mazda’s SkyActiv-D 2.2L diesel doesn’t show cracked cylinder head symptom, when the coolant is spraying all over the engine bay!



The TSB you mentioned is only for cracked cylinder head on the 2.5T. Mazda has never issued a TSB for the same problem on the 2.5L NA with CD. But the reason for cracked head on the 2.5L NA with CD could be similar, the head strength got compromised when Mazda modified the cylinder head on 2.5L NA for cylinder deactivation, and for turbo. The 2.5L NA with CD engine tear-down video from Ukraine / Russia posted earlier in this thread has exposed the cracked area with 2 mm thin wall which indicates the weakness of the crack area.

And as far as anyone knows, there has been no revision of the head in the 2.5L NA, which is still being used in the CX5s built today (& others like the CX-50). So, these engines could crack open like an egg all day long.

 

[capnbfg]

I did the same on my CX9 when I put on the receiver. No way could you transfer any force to that area even if you dropped the muff all the way. There is a flex pipe upstream of the cat and presilancer. ( resonator)

Ok, good to know. Thanks for clarifying.

 

[DianeJinOK]

And as far as anyone knows, there has been no revision of the head in the 2.5L NA, which is still being used in the CX5s built today (& others like the CX-50). So, these engines could crack open like an egg all day long.

Exactly. As per my previous post (a few months ago) my 2022 CX-5 NA with CD had the cracked cylinder head with only 13,000 miles on it. Never overheated. Cylinder head was replaced, but it's anyone's guess as to if/when the replacement will crack. I will consider replacing the car when the warranty is due to run out. A minority of the cars have had this issue, but do I want to take the chance? I'm not sure yet.

 

[Jmaz]

Exactly. As per my previous post (a few months ago) my 2022 CX-5 NA with CD had the cracked cylinder head with only 13,000 miles on it. Never overheated. Cylinder head was replaced, but it's anyone's guess as to if/when the replacement will crack. I will consider replacing the car when the warranty is due to run out. A minority of the cars have had this issue, but do I want to take the chance? I'm not sure yet.

Yes, it's a real shame that Mazda has refined the CX-5 and then tarnished it with the CD related head problems. But apparently the CD related problems didn't end there. The recent thread about the "third gear chirp" which requires the transmission to be removed to change the torque converter because Mazda used a different torque converter in the CD models as opposed to non - CD. If you haven't seen that thread, the member @sinistriel here has shed valuable light on things transmission related. Let's hope he keeps us abreast and also that there are not further CD related issues waiting in the wings.

 

[austinsho]

Folks....first post here. I'm also a victim on the Cylinder Head cracking with oil leaking. Our vehicle was a 2018 red Mazda CX-5. We had 53,000 miles on it when we took it to the dealership for an oil change. The mechanic viewed the engine through a port in the underbelly plastic cover and said we had an oil leak from the timing chain cover and elsewhere.

As it's what I do, I took it to a nearby Japanese auto specialty shop. Their diagnosis was 1) oil pan gasket leak, 2) timing chain cover leak and 3) (you guessed it) oil leaking from the head. This guy I've done business with for more than 20 years said ".....IF you want this fixed, it's an engine out job and should run just over $6200."

His point was obvious...do NOT put money into this car. We sold it the next Monday. Now the tough question. We also have a 2016 Mazda6 with the same engine. Is this problem likely to appear in the older car as well, or just those from 2018 to...when? Another thing, I don't have cylinder deactivation.

I genuinely appreciate any info any of you can provide. I've loved Mazdas since our first Miata back in 2006 and honestly......this entire mess just makes me.....sick.

 

[Jmaz]

Folks....first post here. I'm also a victim on the Cylinder Head cracking with oil leaking. Our vehicle was a 2018 red Mazda CX-5. We had 53,000 miles on it when we took it to the dealership for an oil change. The mechanic viewed the engine through a port in the underbelly plastic cover and said we had an oil leak from the timing chain cover and elsewhere.

As it's what I do, I took it to a nearby Japanese auto specialty shop. Their diagnosis was 1) oil pan gasket leak, 2) timing chain cover leak and 3) (you guessed it) oil leaking from the head. This guy I've done business with for more than 20 years said ".....IF you want this fixed, it's an engine out job and should run just over $6200."

His point was obvious...do NOT put money into this car. We sold it the next Monday. Now the tough question. We also have a 2016 Mazda6 with the same engine. Is this problem likely to appear in the older car as well, or just those from 2018 to...when? Another thing, I don't have cylinder deactivation.

I genuinely appreciate any info any of you can provide. I've loved Mazdas since our first Miata back in 2006 and honestly......this entire mess just makes me.....sick.

If it doesn't have CD I wouldn't worry about the 2016 Mazda 6. I don't recall anyone on this forum without CD worrying about impending failure and wanting to get rid of their car. Your 6 is first generation and look at the thread "high mileage CX-5 report in" and notice the significant amount of miles accumulated by Gen1 cars without failure. I'm certainly not worried about my non-CD Gen1 2014 having head failure. Maybe some of the members here with more knowledge can give you some assurance.

 

[austinsho]

Thanks for the kind words. What I had were two engines, apparently the same, no CD in either, but built two years apart. The newer one failed, the 2016 is still chugging along. Long may it chug!

 

[ruthrj]

Thanks for the kind words. What I had were two engines, apparently the same, no CD in either, but built two years apart. The newer one failed, the 2016 is still chugging along. Long may it chug!

2018 was the first model year Mazda implemented cylinder deactivation on the CX-5. Even though your 6 and CX-5 both have a 2.5 liter engine, your 6 doesn’t have the cylinder deactivation feature your CX-5 had.

 

[yrwei52]

Thanks for the kind words. What I had were two engines, apparently the same, no CD in either, but built two years apart. The newer one failed, the 2016 is still chugging along. Long may it chug!

You got lucky and got rid of your 2018 CX-5 with cracked head really fast! But no worries on the 2.5L NA in your 2016 Mazda 6. The cracked cylinder head problem only happens on 2.5L NA with cylinder deactivation (and the 2.5T in different area with coolant leak) which was introduced in 2018 MY on CX-5. Yeah they’re not the same SkyActiv-G 2.5L naturally aspirated engines and the one with cylinder deactivation has significant changes to the cylinder head and many other component changes including transmission even the exhaust system. IMO Mazda modified the cylinder head from original 2.5L to accommodate many components used only for cylinder deactivation such as switchable hydraulic lash adjusters which apparently impacted the structure strength in certain area of the head, Hence the crack could potentially happen and nobody can tell when.

 

[austinsho]

To my knowledge, I did not have cylinder deactivation. That's not something I would have had and not known about it, right? Or is the situation that ALL cylinder heads were redesigned, whether the car was made with CD or not?

 

[yrwei52]

To my knowledge, I did not have cylinder deactivation. That's not something I would have had and not known about it, right? Or is the situation that ALL cylinder heads were redesigned, whether the car was made with CD or not?

Yes, your 2018 CX-5 did have cylinder activation. With CD, the cylinder head has to be redesigned for CD components.

I was planning to get a new 2018 CX-5 back then and somehow Mazda didn’t advertise too much the CD for some reason. Since I found out and nobody at the dealership knew anything about the availability of CD! I eventually confirmed this with Mazda North American Operations and even that took several reps to confirm. Of course I gave up the purchase plan immediately since I really dislike the design concept of the CD and the history has proved that the CD is a bad idea too.

 

[austinsho]

Well, thanks for the info very, very much. I had NO idea that our 2018 CX-5 was...afflicted...with cylinder deactivation. The last time I fooled with that technology, it was 1981 and I was trying to figure out the issues with my mother's then-new Cadillac V8-6-4! Given the technology of the time, it was amazing it worked as well as it did for GM!

But back to reality. From what I gather, this issue afflicts the 2018, 2019 and perhaps 2020 CX-5s. I gave my 2016 Mazda6 to my daughter and from what I can tell, she doesn't have to worry about this. I, however, was thinking about a 2018-2020 Mazda6 to replace it and am now concerned that it might suffer the same malady. I'm betting that your issues with getting Mazda to admit that this...feature...was indeed there was due to its already bad reputation.

 

[yrwei52]

Well, thanks for the info very, very much. I had NO idea that our 2018 CX-5 was...afflicted...with cylinder deactivation. The last time I fooled with that technology, it was 1981 and I was trying to figure out the issues with my mother's then-new Cadillac V8-6-4! Given the technology of the time, it was amazing it worked as well as it did for GM!

But back to reality. From what I gather, this issue afflicts the 2018, 2019 and perhaps 2020 CX-5s. I gave my 2016 Mazda6 to my daughter and from what I can tell, she doesn't have to worry about this. I, however, was thinking about a 2018-2020 Mazda6 to replace it and am now concerned that it might suffer the same malady. I'm betting that your issues with getting Mazda to admit that this...feature...was indeed there was due to its already bad reputation.

Not like the 2.5T, Mazda has never updated the cylinder head used for the cylinder deactivation. May be because it happens less, but to me the potential of cracked head will be always there. I wouldn’t consider any engine features CD, including the newer Mazda’s with 2.5L NA with CD. On the other hand although the 2.5T has the updated head and exhaust manifold gasket to fight against cracked head since 2021, I won’t consider it either until enough time to prove the updates are effective.

 

[DianeJinOK]

But back to reality. From what I gather, this issue afflicts the 2018, 2019 and perhaps 2020 CX-5s.

It potentially afflicts the CX-5's up to the present day. Apparently the cylinder head has not been redesigned. Mine was a 2022 CX-5 with cracked cylinder head.

 

[austinsho]

I can only assume that as time goes on, there will be more and more of these post-2018 2.5L engines suffering the same failure. I can understand why Mazda hasn't gone public with it, as this engine is in the vast majority of its cars and has been for years. But has anyone ever come forth with a percentage of the produced vehicles over the past five years that have had the issue?

 

[sm1ke]

I can only assume that as time goes on, there will be more and more of these post-2018 2.5L engines suffering the same failure. I can understand why Mazda hasn't gone public with it, as this engine is in the vast majority of its cars and has been for years. But has anyone ever come forth with a percentage of the produced vehicles over the past five years that have had the issue?

It would be nearly impossible to get an accurate number, as only the manufacturer would know for sure, and there's no way they would disclose that percentage unless they were legally obligated to do so.

One thing is for sure - if there is a TSB or recall for a specific issue, it means that the manufacturer is aware of the issue and the TSB/recall was issued because either the problem is serious enough to warrant it, or because the problem affects enough units that they needed to provide a resource to refer to internally (TSB) to make the diagnosis/repair process more streamlined.

 

[austinsho]

That does make perfect sense and was the answer that I didn't want to hear . I guess the killer for me was that even if Mazda did pick up the tab for the repair, that it would be repaired with the same parts that failed. So we just...cut bait. Makes me sick. We both loved the car, but it was simply financially idiotic to go any further.

 

[ctbale]

I dont think the NA CD head, (18 and later) has a TSB? If it doesn't its because one of two reasons. Hasn't happened enough or there is no fix. Or both?

 

[yrwei52]

I dont think the NA CD head, (18 and later) has a TSB? If it doesn't its because one of two reasons. Hasn't happened enough or there is no fix. Or both?

Yes, agreed!