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  1. J

    Engine coolant leak 2016-2020 CX-9 Signature

    Precisely. Mazda managed to jam the engine in so tight that you need to pull it to replace the head all by themselves, without Ford's help. Keep that in mind the next time everyone blames Ford for all the problems on the previous generation
  2. J

    2007~2015 Mo Powah Babeh!

    The engine in the CX-9 is not the same as the MKX. The MKX got variable timing on the intake and exhaust valves whereas the CX-9 has it on the intake valves only. The CX-9 makes about as much horsepower as the most powerful version of this engine that was installed in any other car, it's down...
  3. J

    Another Octane Question

    The air pressure above 8000 feet is about 75% of what it is at sea level. The engine is compressing a much less dense fuel/air mixture, so the peak cylinder pressure and temperature are low enough to not predetonate the fuel/air mixture. As long as the engine isn't pinging, you are fine.
  4. J

    Engine coolant leak 2016-2020 CX-9 Signature

    I guess Ford was not the only source of bad ideas in the Ford/Mazda partnership. It kind of blows my mind that you have to pull the engine to change the head... Especially with how large the hood/front end is on these cars.
  5. J

    Engine coolant leak 2016-2020 CX-9 Signature

    Why did they pull the entire engine to only replace the head?
  6. J

    Engine coolant leak 2016-2020 CX-9 Signature

    The explanations for these coolant leaks aren't making a lot of sense... Why replace the entire long block if the damage is limited to the head? This is turning a $2000 job into a $5000 job.
  7. J

    Exploding Sun Roof on 2020 CX-5 Grand Touring

    It is tempered glass. The glass itself is always under stress. All it needs is something to disturb the equilibrium between the surface (under compression) and the middle (under tension). This can be caused by impurities in the glass itself, so nothing need change for a piece of tempered...
  8. J

    Exploding Sun Roof on 2020 CX-5 Grand Touring

    The Consumer Reports article states that this happens every month of the year all over the world. It seems unlikely that temperature is a primary cause given the failures aren't correlated to climate or season.
  9. J

    Exploding Sun Roof on 2020 CX-5 Grand Touring

    Mazda also picked up the tab for a CX-9 sunroof: https://www.mazdas247.com/forum/index.php?threads/sunroof-exploded.123873600/unread Maybe you should PM one or both of these folks and see if they have any advice.
  10. J

    Exploding Sun Roof on 2020 CX-5 Grand Touring

    Frankly, Mazda not assuming any responsibility is no surprise to me. They claim to want to be a premium brand but don't treat their customers any better than hyundai or chevrolet. Your next step could be insurance. They will cover a new windshield, file a claim and see if they will cover this.
  11. J

    Disable Cylinder Deactivation

    The Mazda renderings of the valve train don't show that cylinders 2 and 3 are equipped with the hardware required to deactivate the valves, at least on the 2018 version.
  12. J

    Disable Cylinder Deactivation

    I think most cars on the road stop injecting fuel when you are coasting down or engine braking. That's not really cylinder deactivation, it's just a benefit of electronic fuel injection. When the display says zero cylinders it's just not injecting fuel because there is no load on the engine.
  13. J

    i-ACTIVE AWD not so Active

    It appears that the 2020 CX-9 got a better "off road" mode: It doesn't get stuck now when a wheel loses traction completely.
  14. J

    Cylinder Deactivation Update

    Yes. They keep the valves closed and the piston compresses the air and then the compressed air pushes the piston back down. They do this to avoid cooling the deactivated cylinders too much which would create big temperature gradients across the engine. Also, keeping the valves closed...
  15. J

    Exploding Sun Roof on 2020 CX-5 Grand Touring

    This can be filed in the "sh*t happens" category. It's made of tempered glass, so there's an enormous amount of internal stress in the glass just sitting there. Any small defect on the edge or damage due to an impact can cause it to shatter at a seemingly random time. Take it to the dealer...
  16. J

    2013~2016 Belt Tensioner - Shouldn't this be a warranty item?

    There is a cutaway view of one of these on the rockauto web site. They are designed to provide more damping force in one direction. It doesn't need to be sealed to work properly, although it certainly would make it less prone to leaking.
  17. J

    CX-9 stress fractures?

    There is another thread on this forum entitled "disappointed with the CPO warranty" or something similar. There is a TSB referenced in there that covers this exact problem. Your photo looks like it was copied out of the TSB document (it's on the internet). You have a textbook case, I'd say.
  18. J

    Anyone install a CX-5 cold air intake?

    So there's a 6 kPa pressure drop, max, due to the presence of the entire intake system and filter. This is ~6%, which places an upper bound on the most horsepower you could hope to gain with one of these systems. In reality, it will be less because the new intake doesn't remove all the...
  19. J

    Anyone install a CX-5 cold air intake?

    There are tests out there that show more contamination of the oil when a "high flow" air filter is used. This makes sense as the filters tend to be less efficient at removing very fine particles from the air, which end up sneaking past the piston rings and get into the oil. However, most of...
  20. J

    2013~2016 Belt Tensioner - Shouldn't this be a warranty item?

    The tensioner on my Accord started to fail. Most of the time there weren't any symptoms. However, whenever the A/C compressor kicked on, the belt would squeal for about half a second - more like a chirp. It looks an awful lot like this one, so I imagine you'd experience something similar.
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