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2016 CX-9 Signature leaking coolant

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Mazda 2 touring
Hey guys,

This weekend the CX-9 started leaking and burning coolant. I took a look at the engine bay and I couldn’t find a leak around the any of the hoses. However, it seems to be leaking from the firewall side. I’ve made an appointment with the dealer, for this coming Saturday. I’ve been reading through the forum and this seems to be a problem, that is affecting the 2016 model years.

I’ll update as I learn more.

2016 signature
39,000 miles
 
Solution
Hey guys,

So I dropped off the CX9 today and this is a known issue (2016 model years). The service assistant confirmed this, even before I took in the car. Once the car was inspected, they determined a new engine would be required. However, they are in back order and I’ll get more information on Monday. I’ll try to get photos of the engine and more details if possible.

I think my build date is March or April 2016.
There can be quite a difference. As @sm1ke said, check it at the same time, at the same heat every time. If you are leaking into the cylinder, you wouldn’t have any coolant on the ground as it would be burning and sent out the exhaust. My car right before this was leaking into the cylinder. There was a slightly fruity smell every time I parked it in the garage and I had to top off coolant about once every other week. No pools on the ground when it was parked
Now that you mention it, I can smell a strong odor as well during cold start. Will this leak accelerate engine failure? What will happen if this thing keep leaking into cylinder for a long period of time? I really like the car and plan to using it for at least 5 years. And now it is only 6 months. And complain to dealer for engine replacement would impossible thing to do in my country.
 
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On my car, when the reservoir level is checked after I get to work (hot engine), it's right below the top of the "F". If I check it around noon (cool engine, about 5 hours later), the level is about an inch and a half below the full mark.
That is still ok I think. Mine is almost near "E" mark. I will get you a photo tomorrow morning.
 
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sm1ke

Work In Progress..
Moderator
Contributor
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Canada
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'18 CX-9 Signature
That is still ok I think. Mine is almost near "E" mark. I will get you a photo tomorrow morning.

If there are no other symptoms (coolant smell, pooling/drip marks on the floor), watching the fluid level will help you determine if there is a leak. Just be sure to be consistent about when you check the level.
 
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If there are no other symptoms (coolant smell, pooling/drip marks on the floor), watching the fluid level will help you determine if there is a leak. Just be sure to be consistent about when you check the level.
I just went through this with my 2016, I first noticed it when I was coming out of a car wash and the car overheated, I never once had a puddle of coolant on my garage floor, or in parking lots. It can be very difficult to notice without checking coolant regularly. I have a replaced engine, I could be wrong but I haven’t seen this happen on newer model years than 2016, so hopefully Mazda fixed the issue on the newer engines. It also could just be that many people aren’t at high enough mileage yet on newer model years.
 
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sm1ke

Work In Progress..
Moderator
Contributor
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Canada
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'18 CX-9 Signature
I just went through this with my 2016, I first noticed it when I was coming out of a car wash and the car overheated, I never once had a puddle of coolant on my garage floor, or in parking lots. It can be very difficult to notice without checking coolant regularly. I have a replaced engine, I could be wrong but I haven’t seen this happen on newer model years than 2016, so hopefully Mazda fixed the issue on the newer engines. It also could just be that many people aren’t at high enough mileage yet on newer model years.

Very true, with all of the undercarriage plastic shields, the pooling might be easy to miss. It seems the best way to keep track is to check your coolant level periodically (if you think there may be an issue).

I believe I've seen one or two reports of this issue happening on a 2017 and a 2018. Possibly mine (2018 w 57.5k kms) as well.. I have an oil change coming up, and I plan to send another sample out for analysis to compare with the first, but since topping up the coolant, I don't think the levels have dropped, and I have none of the other symptoms as far as I can tell (crossing my fingers).
 
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This thread is news to me, but I’m glad I found it. I’ve got a ‘18 GT, with ~39k miles. I went through a whole ordeal with the dealer about cylinder misfires that they couldn’t solve, and I ended up replacing the spark plugs myself and the problem *mostly* went away. I’ve randomly smelled coolant from my car after long drives, but dismissed it because I never saw anything pooling or leaking. My coolant level last night when the car was cold is about 1/2 inch above the “LOW” mark, so I’ll keep my eyes on it. No overheating, but still the occasional studder that feels like misfiring but no CEL or anything. Some days it drives like new, and some days it drives like poo….

Based on this, is there a TSB or something I can take back to the dealer and say “HEY LOOK AT THIS…” because they repeatedly just told me “we can’t find a problem” and sent me on my way until the CEL came on in front of them for a cylinder 3 misfire. They claim they did all sorts of tests (including a compression test) and still nothing wrong…
 
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