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

[kdaug]

Does the issue have anything to do with cylinder deactivation?
I just heard that, due to supply chain issues, vehicles built in October and November 2023 will be missing cylinder deactivation and the iStop auto start/stop. The window sticker will show an MPG decrease on the affected vehicles.
If that also solves the cracked cylinder head issue, I might jump on that and buy a CX-5 manufactured during this time window.

Apparently, most of the cracked head issues seem to be happening with 2.5L NA models with CD but there have also been issues with the 2.5L turbo models. The NA CD models I believe tend to ooze oil out of the cracks in the head in the rear of the engine between cylinders 3 and 4 just above the exhaust manifold, while most of the turbo models with cracked heads tend to leak coolant, if I'm not mistaken.

Avoiding a CD model seems to be a decision that a few others have now wanted to do, but it remains to be seen if all CD models will eventually display cracked heads. We live in hope that Mazda will eventually own up to exactly what caused the problem. It is unlikely they will do a recall but an extension of the warranty would go a long way in restoring faith amongst many who own models with CD.

For the record, the 5 year warranty on my 2018 NA 2.5L with CD expires the end of next month and while I'm not experiencing any problems at 58,000 km I'm a little worried what might happen post 2023. I don't drive my CX-5 hard, but I'm starting to baby it a bit more going forward.

 

[ctbale]

Does the issue have anything to do with cylinder deactivation?
I just heard that, due to supply chain issues, vehicles built in October and November 2023 will be missing cylinder deactivation and the iStop auto start/stop. The window sticker will show an MPG decrease on the affected vehicles.
If that also solves the cracked cylinder head issue, I might jump on that and buy a CX-5 manufactured during this time window.

Where did you hear this? And if true that would be nice for sure! I think they would have to use the pre 2018 head for that. So I guess it's possible. Never heard of a pre 2018 2.5 NA head cracking.

 

[Flight200]

Where did you hear this? And if true that would be nice for sure! I think they would have to use the pre 2018 head for that. So I guess it's possible. Never heard of a pre 2018 2.5 NA head cracking.

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[Flight200]

It will lose 3 MPG city and 2 MPG highway with the features removed.

 

[Flight200]

Where did you hear this? And if true that would be nice for sure! I think they would have to use the pre 2018 head for that. So I guess it's possible. Never heard of a pre 2018 2.5 NA head cracking.

Why can’t they remove stop start and CD and still keep using problematic heads at the same time?

 

[ctbale]

Why can’t they remove stop start and CD and still keep using problematic heads at the same time?

Good question. I think there are provisions in the CD head like machining for deactivation devices on the valve train, maybe oil control lines etc where it might be simpler to just start re-casting the original head? Dunno

 

[ctbale]

View attachment 323762
It will lose 3 MPG city and 2 MPG highway with the features removed.

Worth it. I almost purchased a 22 cx5. But at the last moment I discovered it had CD. Then almost got a 5 with the turbo, didn't want to pay $41k so I got the turbo in my 9 out the door for 37,450. Very happy

 

[CX5Nut]

So had an oil change at the Dealer today and asked about the cracked heads in the NA 2.5 L. They said they have seen very few, maybe 1. And that they believe it's from overheating the engine. Service Writer said it's his understanding that excessive heat is causing the heads to crack.

Have any here who had this issue had their engines overheat?

Would love to find out what Mazda engineers really think is going on.

 

[Flight200]

So had an oil change at the Dealer today and asked about the cracked heads in the NA 2.5 L. They said they have seen very few, maybe 1. And that they believe it's from overheating the engine. Service Writer said it's his understanding that excessive heat is causing the heads to crack.

Have any here who had this issue had their engines overheat?

Would love to find out what Mazda engineers really think is going on.

Even if that were true, that would be an issue in itself. It’s difficult to overheat a modern car that doesn’t have some other failure causing it to overheat.

 

[madar]

Even if that were true, that would be an issue in itself. It’s difficult to overheat a modern car that doesn’t have some other failure causing it to overheat.

It might be from the temperature differences from the cylinders deactivating and running cooler than the ones that are running.

Video on CD damage on a Honda CD v6 engine. Damage part is around the 11:40 mark.

https://www.youtube.com/watch?v=iVGCQ-oUB90

IMO it's just a bad idea, always has been, always will be.

 

[CX5Nut]

Even if that were true, that would be an issue in itself. It’s difficult to overheat a modern car that doesn’t have some other failure causing it to overheat.

True. I haven't seen a car overheat in 30 years! Maybe running the car in very hot condtions does it? Or maybe when CD kicks in the head is running at different temps and the temp differential does it?

The Writer said it overheats because people don't keep an eye on their coolant and it gets low causing an overheating condition.

And as expected, they swore up and down that it's not a Mazda manufacturing issue, it's an owner issue!

 

[edmaz]

So had an oil change at the Dealer today and asked about the cracked heads in the NA 2.5 L. They said they have seen very few, maybe 1. And that they believe it's from overheating the engine. Service Writer said it's his understanding that excessive heat is causing the heads to crack.
.....

....

The Writer said it overheats because people don't keep an eye on their coolant and it gets low causing an overheating condition. .....

It would be even more amusing to hear his explanation about how the coolant "gets low".

That's absolute TOTAL BS IMO, and also the number of incidents as well.

 

[ruthrj]

View attachment 323762
It will lose 3 MPG city and 2 MPG highway with the features removed.

 

[capnbfg]

Hi folks. Thanks for all the information shared in this thread. It was really useful to understand what went wrong with my wife's 2018 CX-5 NA and what to expect from Mazda.

Previously the vehicle had no leaks at all. Then last Thursday my wife was on a short ~30min drive, about 20min in she started smelling smoke, and shortly after that the oil level light came on. When I went to retrieve the car it was down ~1L and there was oil all over the passenger side of the engine compartment. I brought it to my mechanic and although we couldn't see the source of the leak we narrowed it down to somewhere between the head gasket and valve cover gasket. Then I found this thread which explained the rest!

The dealer confirmed it was a cracked cylinder head. The vehicle only has 56K miles but is 4 months beyond the powertrain warranty period. Mazda approved a head replacement, covered all the parts, and we just owed $1200 for labor. The turnaround time from drop-off to pick-up was exactly 1 week.

 

[Flight200]

True. I haven't seen a car overheat in 30 years! Maybe running the car in very hot condtions does it? Or maybe when CD kicks in the head is running at different temps and the temp differential does it?

The Writer said it overheats because people don't keep an eye on their coolant and it gets low causing an overheating condition.

And as expected, they swore up and down that it's not a Mazda manufacturing issue, it's an owner issue!

Even “very hot weather” shouldn’t do it. Plenty of people driving around in Phoenix in August without overheating.
Overheating would most likely be caused be a cooling system failure or else abuse such as towing beyond the vehicle’s limits etc..

 

[yrwei52]

Hi folks. Thanks for all the information shared in this thread. It was really useful to understand what went wrong with my wife's 2018 CX-5 NA and what to expect from Mazda.

Previously the vehicle had no leaks at all. Then last Thursday my wife was on a short ~30min drive, about 20min in she started smelling smoke, and shortly after that the oil level light came on. When I went to retrieve the car it was down ~1L and there was oil all over the passenger side of the engine compartment. I brought it to my mechanic and although we couldn't see the source of the leak we narrowed it down to somewhere between the head gasket and valve cover gasket. Then I found this thread which explained the rest!

The dealer confirmed it was a cracked cylinder head. The vehicle only has 56K miles but is 4 months beyond the powertrain warranty period. Mazda approved a head replacement, covered all the parts, and we just owed $1200 for labor. The turnaround time from drop-off to pick-up was exactly 1 week.

Thanks for the report! Glad to see MNAO was willing to cover the parts even though your 2018 CX-5 is 4 months past the powertrain warranty.

 

[CX5Nut]

Hi folks. Thanks for all the information shared in this thread. It was really useful to understand what went wrong with my wife's 2018 CX-5 NA and what to expect from Mazda.

Previously the vehicle had no leaks at all. Then last Thursday my wife was on a short ~30min drive, about 20min in she started smelling smoke, and shortly after that the oil level light came on. When I went to retrieve the car it was down ~1L and there was oil all over the passenger side of the engine compartment. I brought it to my mechanic and although we couldn't see the source of the leak we narrowed it down to somewhere between the head gasket and valve cover gasket. Then I found this thread which explained the rest!

The dealer confirmed it was a cracked cylinder head. The vehicle only has 56K miles but is 4 months beyond the powertrain warranty period. Mazda approved a head replacement, covered all the parts, and we just owed $1200 for labor. The turnaround time from drop-off to pick-up was exactly 1 week.

Ask them why this would happen and see what they say. Has your cx5 ever overheated?

 

[capnbfg]

Ask them why this would happen and see what they say. Has your cx5 ever overheated?

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.

>> Rampant Misinformed speculation below. Doesn't seem to be related to the leak.


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

 

[CX5Nut]

Interesting. I wonder if this situation starts off as a small crack that then becomes apparent over time, or if just one day the head suddenly cracks open spilling huge amounts of oil.

 

[ctbale]

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.

>> 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

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)