Engine coolant leak 2016-2020 CX-9 Signature

I have the same problem... I put some liquid moly additive to the coolant and now it consume the reservoir every 2-3 month... The leak began 2 month after warranty was over...
 
I have the same problem... I put some liquid moly additive to the coolant and now it consume the reservoir every 2-3 month... The leak began 2 month after warranty was over...
Sorry to hear, have you taken it in to get looked at yet, the leak could be coming from the head like mine, or it could be somewhere else. worst case is it mixes with the engine oil and kills the engine. don't wait to long to get fixed. even though it is over the warranty, they may work with you like my dealership did. please post what you find out so we can keep track of this..
 
I live in Dominican Republic and u went to Mazda Dealer.. They scope the problem and its leaking from a blind plug on the head Cylinder... It dont afect the vehicle but I will have to remove the turbo manifold to remove the bolt and seal it with some silicon... I dont want to remove the engine only for that... If the leak remain like its now I will let it there...
 
This is the first time I have a almost NEW vehicle and in less than 6 month have coolant leak an front driver side clunking noise.... Im very disapointed but love it becuade its very complete...
 
Problems like these are a good case for extended warranties (100k or more on power-train). You can find issues with ANY brand or make of car, low mileage, high mileage etc. If it's made by man it can and will fail at some point. No matter how good the car brand is, there's a lot that goes into not just designing the car, but then manufacturing the car enmasse to closely adhere to the engineering samples built for testing. Hopefully everyone gets these issues sorted out, might make a good case for an occasional UOA, if your getting coolant leaking into the lubrication system via the heads, then it would show up in a UOA (among other signs).
 
Thanks for the info, I wi look into it, .aybe get a 2 for one deal for both cars, prob not though. I feel during this COVID time, Mazda sales are way down, so they will probably charge double.
I called the dealer in San Antonio, TX. One dealer said $599 another $399 and another in Austin said $299. I bought my 16 CX9 in Colmar, PA they offered it for $299 too.
 
Reading a few of these coolant leak threads result in engine replacement made me seriously consider the extended warranty now. MY CX-9 is 2019 with 38k currently.
 
There's 125,000 2016-2020 CX-9's on US roads. So far just a handful of these engine issues. Let's hope these examples are outliers as they seem to be.

The 2.5T is also in a ton of 2018+ CX-5's and Mazda6's. And Mazda ranks #1 in reliability suggesting these are rare exceptions.

Still something to keep am eye on but I wouldn't panic yet.
 
There's also 2nd gen CX-9's with over 150,000 miles on them (have seen them listed for sale). Although I couldn't tell service history but pretty sure original engines. There's a '16 on Autotrader right now with 166,500 miles and looking clean.
 
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There's also 2nd CX-9's with over 150,000 miles on them (have seen them listed for sale). Although I couldn't tell service history but pretty sure original engines. There's a '16 on Autotrader right now with 166,500 miles and looking clean.

When I was looking for mine a couple months or so ago, I saw about half a dozen with over 100k miles and about a dozen more getting close. I only saw one with an engine replacement. I wouldn’t buy a used with that many miles but I was curious if there were any common issues with these getting to higher mileage. That being said, I dumped a turbo car with a coolant leak in the engine and will probably be buying an extended warranty because I don’t want to deal with that headache again.
 
My CX-9 2016 also experienced the coolant leak with Coolant warning light on and the coolant level in the reservoir was very low. It has just under 80K miles. I brought it the local Mazda dealership. First, they diagnosed and replaced the thermostat. I brought it home and a day later of driving, the Coolant warning light came back.

I had to add more coolant and took it back to the dealership and this time the service advisor asked me to leave the car there longer for more detail diagnosis. They tore down the engine and found a crack in the cylinder head. They are working with my extended warranty company to get an approval for the repair.

There are other threads in this forum mentioned about coolant leak in Mazda CX-9 2nd gen (2016 is the first year). In some cases, Mazda went ahead replaced the engine (long block?) even though it is out of the 60k power train warranty. In my case, I was told I have to go through my extended warranty company first. I would love to have the whole engine (or at least the long block) replaced as it seems to be an issue that Mazda is aware of.

Will keep everyone posted how the repair goes.
 
My CX-9 2016 also experienced the coolant leak with Coolant warning light on and the coolant level in the reservoir was very low. It has just under 80K miles. I brought it the local Mazda dealership. First, they diagnosed and replaced the thermostat. I brought it home and a day later of driving, the Coolant warning light came back.

I had to add more coolant and took it back to the dealership and this time the service advisor asked me to leave the car there longer for more detail diagnosis. They tore down the engine and found a crack in the cylinder head. They are working with my extended warranty company to get an approval for the repair.

There are other threads in this forum mentioned about coolant leak in Mazda CX-9 2nd gen (2016 is the first year). In some cases, Mazda went ahead replaced the engine (long block?) even though it is out of the 60k power train warranty. In my case, I was told I have to go through my extended warranty company first. I would love to have the whole engine (or at least the long block) replaced as it seems to be an issue that Mazda is aware of.

Will keep everyone posted how the repair goes.
Take the poll and mention your situation in this thread: https://mazdas247.com/forum/t/2-5t-...one-to-prevent.123875515/page-18#post-6741327
 
Thanks, Arock712! It seems like more and more people have the same (coolant leaking) issue. Hope a TSB will come out soon to address this.
I don't want to vote NO at this point yet.
 
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