My CX-9 is having the same issue. Coolant leak.. cracked cylinder. Did you have to pay to have the engine replace? Can you advise me on how to get Mazda USA to pay for it. My car is 2017, with 93K miles.
So, the head replacement is probably in order, though I believe the engine has to come out of the car for them to do the head, so it's pretty much a wash on labor to replace the head vs. replacing the engine. If the "just" do the head, they have to swap everything over onto your "old" engine block and that is a lot of work...seems easier just to do the engine swap, BUT only if MAZDA is paying, right?
Anyway, here I would say if you have a good Mazda dealer, with conscientious and patient service advisors/service managers, they may
be able to get Mazda corporate to pay something towards the repair. In my case, I ended up paying about $2800 on a repair that would have cost close to $7000, which, while I was grumbling that I shouldn't have to pay to have a manufacturer defect on my vehicle repaired, it was better than nothing.
My CX-9 had 78K miles on it at the time, so they may not cover as much of the repair given the higher mileage on your CX-9, but I really don't know. It would help if you have meticulously maintained the vehicle and have detailed service records to provide to them, if they ask; (in my case they apparently asked the dealer to see their
service records for my
vehicle, but I do all my own maintenance
(and keep meticulous records!!) and I offered to share my records with them, but they didn't ask for them. I did write Mazda corporate a "complaint" letter after it was all over and they called/e-mailed me and asked me what I wanted. I told them: 1) a little transparency about what the actual problem is (what is actually causing these heads to fail?) and 2) that they apply a consistent repair policy across the board, don't cover some repairs and not others...cover them all in full, regardless of the mileage, or decide on some pre-set percentage and let the dealers know what the policy is...and apply it consistently
So after that they (Mazda) contacted the dealer to see how much I actually paid for the repair, and based on what the dealer told them, they decided they had paid "enough" and wouldn't pay me any more. Remember, I DID NOT ASK
them for money!! They simply ignored my other requests. I may call them again sometime to close the loop and see if they are able to provide me with what I actually asked them. Meanwhile our car just passed 80K miles and other than an over sensitive TPMS that I have had to reset TWICE since we got our car back, we have had no other issues. Knock on the proverbial wood...🪵