2018 CX-9 Overheating

chris76

Member
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2018 CX-9 Signature
We have a 2018 CX-9 Signature with about 78k miles on the clock. My wife was taking the vehicle through the car wash on her way home from work, and the coolant temp light started flashing briefly. After she exited the car wash, it stopped, so she drove home. When she got home, the radiator fan was running on full blast (strange for an 85 degree day), and the temperature was on the 3/4 mark. I shut down the car and let it cool off, and discovered it was completely out of coolant. We had not experienced any noticeable coolant leaks before this. I had it towed to the dealer and it is being diagnosed. I'm hoping it's not the dreaded cracked cylinder head issue.
 

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Mazda CX-9 Grand Touring 2016
Thanks for your information. Expect a cracked head, but in any case please do let us know what is found and what they'll do for you.
 
Most probably related to the cracked cylinder head issue( Mazda has issues a TSB, changed the engine and exhaust manifold for 2021 & 2022 models).
 

chris76

Member
:
2018 CX-9 Signature
Update on this mystery. Dealer has been diagnosing the car and has yet to find any issue. They filled up the system with coolant and it is holding pressure, no leaks apparent with UV dye. They did a compression check on all 4 cylinders to rule out a bad head gasket, and compression values were normal. They let the car run for several hours according to the service advisor. They are going to road test it tomorrow morning, and I did point out the TSB-01-013-21, which he is going to bring up with the mechanic in the morning.
 
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Mazda CX-9 Grand Touring 2016
Chris, when you get the car back, watch the coolant level in the expansion tank closely. Check it at the same engine temperature each time. Also look where it's usually parked for a green puddle under the engine. Good luck, and please keep us informed.
 

chris76

Member
:
2018 CX-9 Signature
Update, the dealer kept the car for additional diagnostics. They examined all of the cylinders with a borescope camera and determined that there was a difference in visual appearance of cylinders 1 and 4, showing carbon buildup which is indicative of coolant intrusion into the combustion chamber. (Obviously, if the coolant wasn't leaking it was getting burned.) They apparently took pictures but I haven't been back to the dealer to see them yet.

The dealer now wants to replace the entire head assembly, because apparently, the cost difference between doing the gasket alone and replacing the entire head is minimal, and the cracks caused by the casting flaws in TSB-01-013-21 have been known to occur after the head gasket was replaced and the head was torqued down with new bolts.

The good thing is that I have Geico mechanical breakdown insurance so it should all be covered except for $250.00. I haven't seen the estimate yet, but I'm sure it will be expensive. I will ask if there is any chance of a goodwill repair through Mazda, so I don't have to use my insurance, but I'm not hopeful. What a major defect for a $40,000 vehicle to have a catastrophic failure at 78,000 miles.
 
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All they had to do is use an exhaust gas leak test with special fluid that turns yellow from blue with the presence of exhaust gases in your coolant. It is a turkey baster type device that has a rubber stopper that goes on top of the coolant tank and a rubber bulb which you squeeze to suck up gasses from the tank into the clear tube that the color changing leak test fluid sits in. It can instantly tell if there is a head crack or blown head gasket.
 
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18 Mazda CX5 AW
All they had to do is use an exhaust gas leak test with special fluid that turns yellow from blue with the presence of exhaust gases in your coolant. It is a turkey baster type device that has a rubber stopper that goes on top of the coolant tank and a rubber bulb which you squeeze to suck up gasses from the tank into the clear tube that the color changing leak test fluid sits in. It can instantly tell if there is a head crack or blown head gasket.
Yeah. But he's outta warranty and they can't charge hourly for that simple test.
 

chris76

Member
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2018 CX-9 Signature
Here's the itemization:
$4,953.53 Cylinder Head Assembly with Bolts
$514.26 Seals and Gaskets - Head Gasket Kit
$272.97 Seals and Gaskets - Exhaust Manifold and Turbo Gaskets
$28.62 Coolant
$189.95 AC Recharge/Refresh
$271.14 Thermostat Replacement
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$6,230.47

My question: If there was an internal coolant leak into the cylinder, can they really guarantee that there was no damage to the bottom half of the engine? It seems that when this issue occurs during the warranty period, Mazda is replacing the entire long block. I'm going to file a claim through Geico but is there any way I can verify that they're not just putting a new head on a damaged block?
 
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18 Mazda CX5 AW
Here's the itemization:
$4,953.53 Cylinder Head Assembly with Bolts
$514.26 Seals and Gaskets - Head Gasket Kit
$272.97 Seals and Gaskets - Exhaust Manifold and Turbo Gaskets
$28.62 Coolant
$189.95 AC Recharge/Refresh
$271.14 Thermostat Replacement
------------------------------------------------------
$6,230.47

My question: If there was an internal coolant leak into the cylinder, can they really guarantee that there was no damage to the bottom half of the engine? It seems that when this issue occurs during the warranty period, Mazda is replacing the entire long block. I'm going to file a claim through Geico but is there any way I can verify that they're not just putting a new head on a damaged block?
Above quote doesnt mention a new or refurbished engine.

They are replacing the head and seals.

If you think the engine beyond repair, have it looked at by an independant mechanic or an indy engine repair/machine shop.

Get a second opinion if you disagree.

Imo, your paying for alot of labor versus a new engine install with minimum labor.

A salvage engine installed shouldnt cost too much more.

And say a new engine install cost $2000 to $3000 more and if you have to make up the difference( if insurance will only pay for the $6000 head replacement), is it worth it for a new engine to you ?

Get a 2nd opinion and get pricing for a new (or refurbished) engine install before making decision.
 
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chris76

Member
:
2018 CX-9 Signature
Above quote doesnt mention a new or refurbished engine.

They are replacing the head and seals.

If you think the engine beyond repair, have it looked at by an independant mechanic or an indy engine repair/machine shop.

Get a second opinion if you disagree.

Imo, your paying for alot of labor versus a new engine install with minimum labor.

A salvage engine installed shouldnt cost too much more.
Correct, this is for a head replacement only. I don't know if there is a way to determine if the bottom half of the engine has suffered any excess damage without disassembly, or at least an oil analysis. I think spending thousands of dollars to install a salvage engine would be a terrible idea considering the high prevalence of defective heads. Put in a salvage engine with no warranty, and then 10k miles later the head cracks. This is covered under GEICO so I won't be paying except for $250 anyway, so cost isn't the issue.
 
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18 Mazda CX5 AW
Above quote doesnt mention a new or refurbished engine.

They are replacing the head and seals.

Correct, this is for a head replacement only. I don't know if there is a way to determine if the bottom half of the engine has suffered any excess damage without disassembly, or at least an oil analysis. I think spending thousands of dollars to install a salvage engine would be a terrible idea considering the high prevalence of defective heads. Put in a salvage engine with no warranty, and then 10k miles later the head cracks. This is covered under GEICO so I won't be paying except for $250 anyway, so cost isn't the issue.
Just providing all options.

Like I said, get a 2nd opinion and if your car frame is in decent shape(no/minimal rust) and a new engine install isnt completly covered, imo, I would pay the difference for the new engine install.
 

chris76

Member
:
2018 CX-9 Signature
The dealer says they see no evidence of coolant contamination in the oil, but I think a visual inspection of the dipstick is the only oil analysis they've done.I am sure GEICO will be assigning a claims adjuster to this case, so before they just slap a new head on the block, I will definitely ask about what diagnostic steps are being taken to make sure the bottom half of the engine didn't suffer any damage.

I have to say, for a modern Japanese vehicle to have an internal coolant leak at 78k miles is totally unacceptable. We love the car but at this point, I'm not sure we want to keep it past 100,000 miles once our GEICO mechanical breakdown coverage expires.
 
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Northeast
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2020 CX-5 Tour
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My question: If there was an internal coolant leak into the cylinder, can they really guarantee that there was no damage to the bottom half of the engine?
The only way to do that would be to disassemble the entire engine, and then carefully examine and measure each part, including the cylinder walls. Given that no one is ever going to consider doing that, the answer to your question is that no one can even come close to knowing how much (if any) significant damage has been done to the bottom of this engine.

And unfortunately for you, Mazda can make the repair any way they choose to, as long as they give the vehicle back to you in good running condition, with no identifiable issues. I doubt if Mazda would ever cave and give you a long block, but if you're game for that type of battle, by all means give it a go, because you have nothing to lose by doing so.
 

chris76

Member
:
2018 CX-9 Signature
The only way to do that would be to disassemble the entire engine, and then carefully examine and measure each part, including the cylinder walls. Given that no one is ever going to consider doing that, the answer to your question is that no one can even come close to knowing how much (if any) significant damage has been done to the bottom of this engine.

And unfortunately for you, Mazda can make the repair any way they choose to, as long as they give the vehicle back to you in good running condition, with no identifiable issues. I doubt if Mazda would ever cave and give you a long block, but if you're game for that type of battle, by all means give it a go, because you have nothing to lose by doing so.
I'm not even pursuing action through Mazda at this point, because I think it will be a futile effort, especially once they find out that I have insurance that will cover the repair. If an oil lab analysis finds no metal, gasoline or coolant contamination in the bottom half, I'll feel relatively confident that the bottom half is sound. But I'm still going to get rid of the vehicle, most likely.
 
Sorry to hear about this.

Far too many cases of this happening.

I'm going to ditch my car before the 5 year / 60K mile powertrain warranty expires.
 
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18 Mazda CX5 AW
Sorry to hear about this.

Far too many cases of this happening.

I'm going to ditch my car before the 5 year / 60K mile powertrain warranty expires.

Yeah. I now have a 2018 CX5 cpo with 31,000 miles so far. Now you know they know which vehicles have already presented with engine problems and they know which platform models are a problem and if the problems are from across the whole year, certain months or even just narrowed to a particular week/day that production was faulty. If it was only one day, one week or even one month of faulty production, it would be re-assuring if they would come out and let us know. But unfortunately that is something they will probably never do.
 
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2018 CX-9 GT
The TSB has just been updated and cover all cx-9 and cx-5 built before 9 June 2020. So it is not linked to a particular bad day or month at the factory. https://static.nhtsa.gov/odi/tsbs/2022/MC-10215280-0001.pdf

But we don’t know exactly the ratio of incidents and probability of it happening (does it happen on 1% of the fleet, 20% etc). That information is not part of TSBs, and while forums are great information sharing tools, they are terrible tools to make a probability risk assessment.
 

chris76

Member
:
2018 CX-9 Signature
Update: GEICO is working with the dealer on this Mechanical Breakdown Claim. GEICO is unfortunately requiring the cylinder head to be removed and sent to a machine shop to be torn down and measured, even though the price to do so is (according to my service advisor) $200 less expensive than simply ordering a new cylinder head from Mazda and replacing it.

I have to authorize $1575 for 9 hours of machine shop services to have the cylinder head torn down, which if GEICO determines was a "covered repair" I won't be on the hook for. I sure hope GEICO does me right.
 
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