2018 CX-9 Overheating

[chris76]

Yes, me too. Despite my initial skepticism of GEICO, they've pulled through and saved me from a $6,000+ repair bill.

 

[chris76]

Reading through this thread makes me wonder why the industry standard for drivetrain warranties is just 60,000 miles. These days, a vehicle is still in its early stage in life at 60K. The norm should match Hyundai/KIA's 100,000 miles. Every car buyer's expectation is that the engine will run fine well past that.

The example in this post is a good example of what is unacceptable. In no case should someone who spent over $40K on a vehicle 4 years ago be left hanging out to dry because the automaker made an engineering mistake.

You would think that Mazda would want to offer an incentive to buy their products, being that they are a small company. Service advisor told me that he had another customer with an engine that was just past the 60k powertrain warranty, and Mazda was giving him a difficult time with covering the classic TSB 01-012/21 cracked cylinder head failure with external coolant leaking (which was slightly different than my car's issue.) If you're reading this, Mazda USA, this is not a good way to make first time Mazda buyers (like us) repeat Mazda buyers. I wonder how many of these 2016-2018 (and perhaps later) 2.5Ts had bad casting. I'm beginning to think it's a huge percentage. I'd never buy one on the used market.

 

[arock712]

I've owned three Mazdas, but my 2017 had the coolant leak. It was within warranty so Mazda did cover it with a new engine. I love the CX-9, but it bugs me with such a major defect they're not covering their own engineering mistake even out of warranty. They should step-up and just do it, no questions asked.

 

[jal142]

You would think that Mazda would want to offer an incentive to buy their products, being that they are a small company. Service advisor told me that he had another customer with an engine that was just past the 60k powertrain warranty, and Mazda was giving him a difficult time with covering the classic TSB 01-012/21 cracked cylinder head failure with external coolant leaking (which was slightly different than my car's issue.) If you're reading this, Mazda USA, this is not a good way to make first time Mazda buyers (like us) repeat Mazda buyers. I wonder how many of these 2016-2018 (and perhaps later) 2.5Ts had bad casting. I'm beginning to think it's a huge percentage. I'd never buy one on the used market.

Mazda posted a loss, and a rather sizable one at that, in their most recent quarterly results posted on June 30. The blame was pinned on production shortfalls, but one can't help but wonder how much warranty claims are hurting their bottom line.

The company announced price hikes across the board. I suspect Mazda Corporate will be increasingly stingy if their profitability does not improve. Their next quarterly update is due at the end of September...

 

[Jack Rabbit]

Mazda posted a loss, and a rather sizable one at that, in their most recent quarterly results posted on June 30. The blame was pinned on production shortfalls, but one can't help but wonder how much warranty claims are hurting their bottom line.

The company announced price hikes across the board. I suspect Mazda Corporate will be increasingly stingy if their profitability does not improve. Their next quarterly update is due at the end of September...

But these cracked cylinder heads that are showing up shouldnt be across multiple years. Where was the quality control?

They designed a high pressure high temp engine and then apparently the bolts were overtorqued causing micro-cracks which eventually expand to become a problem, hopefully before the warranty is expired. And the high pressures will only exert more force on an already defective head.

I've seen comments on 2014 to 2019 having these cracked cylinder heads across the CX5 and CX9 platforms. At what points did they check the robotic torque machines?

I've never had a non-mazda vehicle crack a head.

It's just not that common on passenger vehicles. Cracked heads usually only occur on race cars and very old vehicles.

They really should have been on top of this. Especially since this was designed as a high pressure engine... Last things you need is a weak cylinder head.

 

[jal142]

But these cracked cylinder heads that are showing up shouldnt be across multiple years. Where was the quality control?

They designed a high pressure high temp engine and then apparently the bolts were overtorqued causing micro-cracks which eventually expand to become a problem, hopefully before the warranty is expired. And the high pressures will only exert more force on an already defective head.

I've seen comments on 2014 to 2019 having these cracked cylinder heads across the CX5 and CX9 platforms. At what points did they check the robotic torque machines?

I've never had a non-mazda vehicle crack a head.

It's just not that common on passenger vehicles. Cracked heads usually only occur on race cars and very old vehicles.

They really should have been on top of this. Especially since this was designed as a high pressure engine... Last things you need is a weak cylinder head.

I don't think you can conclude this problem was due to over-torquing bolts, although it may have contributed. Mazda changed the head design to mitigate the problem. If it was solely down to a bolt torque issue, they would not have required a head casting change.

As far as how this could slip past QC:
1. It took several years of service before these issues started appearing. I'm sure Mazda did some sort of life testing, but it may not have reproduced the combination of heat cycles, mechanical loading, and other effects that real life use placed on the cylinder head.
2. The prototype and qualification blocks and heads were likely cast in a different foundry and then post machined in a different shop than the production blocks and heads. Small differences in alloy composition, mold fabrication, melt pour, post heat treatment and other processing could have yielded different material properties in the metal. It's possible that the testing blocks all passed with flying colors, only for the production blocks to have slightly different material properties which led to the cracking issues now.

And head cracking is a lot more common than you seem to think. If you crack open a Subaru block, for instance, they are notorious for cracking from the spark plug hole to one of the exhaust valves. However, the crack doesn't penetrate the water jacket so most people remain blissfully unaware that there is any issue. Honda has also had an engine or two where this was not unheard of, but again, most people would not realize there were any cracks.

 

[DTam]

You would think that Mazda would want to offer an incentive to buy their products, being that they are a small company. Service advisor told me that he had another customer with an engine that was just past the 60k powertrain warranty, and Mazda was giving him a difficult time with covering the classic TSB 01-012/21 cracked cylinder head failure with external coolant leaking (which was slightly different than my car's issue.) If you're reading this, Mazda USA, this is not a good way to make first time Mazda buyers (like us) repeat Mazda buyers. I wonder how many of these 2016-2018 (and perhaps later) 2.5Ts had bad casting. I'm beginning to think it's a huge percentage. I'd never buy one on the used market.

I just went through this myself. I was at 60.5 months and 59,780 miles on my 2017. Noticed a strong coolant smell during a cold start when backing out of the garage. Scheduled an appointment with the selling dealer for diag. They found that coolant was leaking internally into the cylinder after pressure testing the cooling system. No overheating, no misfire codes. No signs of external leaks anywhere. Oil was not contaminated since the leak was still in the early stages.

The selling dealer also included 100k power train with all vehicles they sell. I paid a total of $350 deductible for the repair. The extended powertrain warranty verbiage stated a $200 a deductible. Apparently my service records of parts receipts and spreadsheet of what was done with the mileage was not acceptable.

Not sure exactly between the dealer and mazda who paid for what. New cylinder head, water pump and all associated gaskets in the TSB was replaced. Total time was just over a week.

 

[chris76]

I’ll post the final invoice here when I get the car back

 

[Jack Rabbit]

I don't think you can conclude this problem was due to over-torquing bolts, although it may have contributed. Mazda changed the head design to mitigate the problem. If it was solely down to a bolt torque issue, they would not have required a head casting change.

As far as how this could slip past QC:
1. It took several years of service before these issues started appearing. I'm sure Mazda did some sort of life testing, but it may not have reproduced the combination of heat cycles, mechanical loading, and other effects that real life use placed on the cylinder head.
2. The prototype and qualification blocks and heads were likely cast in a different foundry and then post machined in a different shop than the production blocks and heads. Small differences in alloy composition, mold fabrication, melt pour, post heat treatment and other processing could have yielded different material properties in the metal. It's possible that the testing blocks all passed with flying colors, only for the production blocks to have slightly different material properties which led to the cracking issues now.

And head cracking is a lot more common than you seem to think. If you crack open a Subaru block, for instance, they are notorious for cracking from the spark plug hole to one of the exhaust valves. However, the crack doesn't penetrate the water jacket so most people remain blissfully unaware that there is any issue. Honda has also had an engine or two where this was not unheard of, but again, most people would not realize there were any cracks.

Thanks for explaining the manufacturing process. It's nice to learn how things are made.

Still, the broken head wouldn't exist without both a & b. A strong head could take some overtorque while correct torque on a weak head might be as ok as well.
Both appear to have contributed to the problem.

Didnt the TSB say overtorque caused the problem hence the redesigned head ?

the cracked head is both a design flaw and a manufacturing flaw.

I haven't owned a subaru so am not familar with their engine problems.

However have owned many fords and toyotas without any engine problems that lasted for 14 + years. Likewise I dont know of anyone else who had these kinds of engine problems with fords or toyotas.

The Mazda is a nice car and handles well and looks great. But at the end of the day, imo, it appears problems like these(and not standing behind the defective product past the warranty period) is what prevents it from being a Top 10 car maker.

Maybe Toyota can help them with quality control at the new toyotas/mazda plant.
Hopefully Toyota learned it's lessons after the gas peddle problems.

The only things we can do to protect our investment before warranty expired is have an ultrasound inspection or other test to find the micro-cracks and prove defective so they'll replace the head. Because theyve clearly taken a catch me if you can position.

 

[Regrets]

WTF are they doing?
Imo, sounds like they are trying to find any reason to deny the claim. Then your gonna be stuck paying a huge disassembly cost and if they deny the claim, stuck without an engine. Then pay additonal $$ on top of that. If they want to evaluate the engine, let them do it at their cost.
Ask them if you can just pay the difference for a new cylinder head...
I would gladly pay $200 for a new head.

Also, check on new engine install pricing and see what that difference is.

Created an account to say our situation is identical in nearly every way to yours. 2018 Mazda Signature. 75k miles. Geico mechanical insurance paid for the fix, but the “fix” was resurfacing, because they mechanic saw no evidence of cracked cylinder head as indicated by the service bulletin.

Well, collected my car, it’s still overheating. They said there was air in the line, so they drained it. Collected and it’s still overheating. They’ve changed the thermostat. Collected and it’s still overheating.

Dropping again off on Monday (4th time).

We loved this car. But I’m done. Mazda btw didn’t do s***. They should replace the motor.

 

[PTguy]

Why are we talking about over tightening the turbocharger bolts during assembly? The TSB says that the cylinder head casting isn't strong enough to carry the weight of the turbocharger and the rest of the exhaust system: