Poll 2.5T Coolant Leak/Engine Replacement. What can be done to prevent?

Who is having coolant leak issues and have had their engines replaced?

  • Yes

    Votes: 8 25.8%
  • No

    Votes: 23 74.2%

  • Total voters
    31
Your photos reminded me of this TSB. Different location on the TSB, but you can see that a limited amount of coolant could be coming from the water pump under normal operation. Not saying this is your case, just to take it into consideration.

That’s a good one to note. It would explain intermittent smells versus a constant leak. My coolant level in the overflow tank was right at the L mark right after driving for 25 minutes so I would have expected a higher level. Either way, I’ve got an appointment this afternoon with my local dealer and we shall see what they find.
 
Welp. That’s another one down. My ‘18 GT is leaking from the engine block.

They said it’s covered under the 5yr/60k powertrain warranty, so it’s no cost to me.

They gave me a CX-5 signature turbo as my loaner, so at least I’m driving something nice in its place.

They also told me that the last one took two months to get the engine and then a week or two to complete the work, so I guess I’m looking at possibly having it back in December.
 
Do you ever do any driving where you are really working the engine, like towing?
Never towed a thing a day in my life. I live near Washington DC, so all I do is drive in traffic. Not a lot of mountains, but the commute is considered “extreme” driving conditions. I occasionally floor it, but who doesn’t? 😁
So definitely not isolated to 16-17s. How many km did you have on it ?

Great loaner though.
Mine had 40,405 miles (roughy 63k km) on it when I noticed the leak. The misfires and poor performance issues started around 30k, and the dealer basically dismissed me until I got a CEL from a misfire. Then they replaced one ignition coil and one spark plug and said that the rest must be my imagination because they couldn’t reproduce it. This made the sixth time (not including basic maintenance) I’ve had it in between 30k and 40k.

At least this time they quickly saw and acknowledged the problem and I’ll eventually end up with some resolution from it. If it is as good as new when I get it back, I’ll be super happy. I loved this car when it was new.

The loaner is nice, but I prefer the driving position in the CX9 much more. My wife has a ‘17 CX5, and I’m sure once she drives this she’ll want to upgrade since the signature trim and turbo engine weren’t available when we bought her car.
 
Do you ever do any driving where you are really working the engine, like towing? Also, what octane do you usually use?
I just noticed the octane question. I always use 92+ octane. 93 octane is my norm, but depending on where I go, it can be 92. I ran one tank of 87 when I first bought it before I knew about the performance difference.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Yup, 2019 model year is when engine was modified, at which point the issue should be fixed.
What modification Mazda did to the 2.5T for 2019 MY? I assume CX-5 got the same modified 2.5T in the same MY?
 

truckster

2021 CX-9 Signature
What modification Mazda did to the 2.5T for 2019 MY? I assume CX-5 got the same modified 2.5T in the same MY?
I was going to ask the same thing. What was done differently with the 2.5 starting in 2019 to hopefully eliminate the coolant leak issue?
 
So I went by the dealer yesterday to ge the rest of my stuff from my car. I spoke with the SA and was told that they’re only replacing the engine block, and that my powertrain warranty is the only warranty I get. I’m at 40k and will be around 43 months since the in-service date so there’s 20k and 17 months left. I recall someone else saying they got 12 months/12k miles but i think they were beyond their powertrain warranty. I’m not sure why, but I feel like that’s kinda insufficient. Maybe I’m just paranoid the service technicians won’t disassemble and reassemble everything correctly. Does this align with everyone else’s experience who’ve had this work done?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
⋯ I spoke with the SA and was told that they’re only replacing the engine block
This’s very strange to me, as the culprit of the coolant leak is usually on cylinder head, not cylinder block.

⋯ and that my powertrain warranty is the only warranty I get. I’m at 40k and will be around 43 months since the in-service date so there’s 20k and 17 months left. I recall someone else saying they got 12 months/12k miles but i think they were beyond their powertrain warranty. I’m not sure why, but I feel like that’s kinda insufficient. Maybe I’m just paranoid the service technicians won’t disassemble and reassemble everything correctly. Does this align with everyone else’s experience who’ve had this work done?
Since your remaining powertrain warranty is longer than standard repair warranty of 12 months / 12K miles, that’s what you get.

If this coolant leak is a design flaw, you definitely want longer warranty. Just wait and see if there’s any future development on this issue.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
This’s very strange to me, as the culprit of the coolant leak is usually on cylinder head, not cylinder block.


Since your remaining powertrain warranty is longer than standard repair warranty of 12 months / 12K miles, that’s what you get.

If this coolant leak is a design flaw, you definitely want longer warranty. Just wait and see if there’s any future development on this issue.

Agree with the above. I personally feel like 12 months/20k isn't enough for an engine replacement/overhaul, but realistically, unless you put very low miles on the new engine during that 12 month period, any issues from a poor installation would probably pop up during that first year.
 
Sounds good. I’m trying to keep myself from trading it in on something. The dealer that has it put a deal together that gets me into a ‘21 signature and keeps my payment exactly where it is, but I’d be starting the loan over and driving essentially the exact same car, but with less miles and a couple extra features.

This has been a sour experience for me, especially since this is the third Mazda I’ve owned, and the second one to need an engine replacement (I had a 2010 Mazda3 that had the timing belt tensioner come loose at 11k miles and wrecked the engine). I like Mazda but I’m finding it hard to stay loyal with these experiences.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
Sounds good. I’m trying to keep myself from trading it in on something. The dealer that has it put a deal together that gets me into a ‘21 signature and keeps my payment exactly where it is, but I’d be starting the loan over and driving essentially the exact same car, but with less miles and a couple extra features.

This has been a sour experience for me, especially since this is the third Mazda I’ve owned, and the second one to need an engine replacement (I had a 2010 Mazda3 that had the timing belt tensioner come loose at 11k miles and wrecked the engine). I like Mazda but I’m finding it hard to stay loyal with these experiences.

That's totally understandable. I feel that if you don't feel confident in something, regardless of any assurances that have been made or warranties that it may come with, you should at least explore your other options. Peace of mind is a very valuable thing.

If you do happen to trade it in, someone else will definitely snap it up, especially in the current market. The deal that your dealership has set up sounds pretty decent, but again, if you've lost confidence in the brand, it can be hard to earn that back. All I can say is that it seems that the newer engines don't have this issue, but it's also still too early to say that with any certainty.
 
:
Winnipeg Canada
:
2017 CX-9 GT
There's also the concept of "the devil I know". To be honest, every car has had some issue that the community dreads. The Supra community dreaded head gasket issues. The Murano community dreaded CVT issues. I never experienced either. However my Honda Prelude lost it's crank bolt and ruined the crank keyway forcing me to rebuild the engine with a new crank (dumbest thing I ever did, I should have just set fire to the car). My point is, all cars have some issue, including Toyota (see above).

But ya, this 2.5L Turbo issue does seem pretty bad. A cracked block/head can't be fixed. At least with the Supras, people would replace the old one with a metal gasket and it was good to go for ever after that. But this seems a little scarier. the irony is one of the reasons I ditched the Murano is because I was nervous about the CVT going, which also requires a full replacement. Maybe I'll just buy my family their own e-Bike and call it a day! :)
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
⋯ All I can say is that it seems that the newer engines don't have this issue, but it's also still too early to say that with any certainty.
If there’s a design flaw, there’s nothing can prevent the same thing happening at certain time; unless Mazda has found the root cause of this coolant leak issue on the 2.5T, and revised the design.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
If there’s a design flaw, there’s nothing can prevent the same thing happening at certain time; unless Mazda has found the root cause of this coolant leak issue on the 2.5T, and revised the design.

I think others have stated that the new engine assembly or cylinder head assembly for 2019 has a revised part number. That revised part number alludes to a revised design.

Unfortunately I don't remember the change in part number or whether that's even true. We're still not even sure this is a design flaw - if it was/is, this issue would probably be a lot more common. This may be a manufacturing or assembly issue that only affects a low percentage of pre-2019 MY CX-9s.

The cylinder head cracking does appear to be the root cause of the "typical" 2.5T coolant leak, however the issue that @s0n1c is having might be slightly different from the "typical" leak. As a result, it may require a different approach.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I think others have stated that the new engine assembly or cylinder head assembly for 2019 has a revised part number. That revised part number alludes to a revised design.
In case of Mazda’s 2.5L with cylinder deactivation, there’s a TSB with new part number for pre-assembled whole cylinder head when dealers have a need to replace the head due oil leak、fallen rocker arms、or noisy switchable hydraulic lash adjuster used for CD.

I wonder the new part number on 2.5T cylinder head serves the same purpose to reduce the cylinder head replacement labor time, it’s not really an indication of a revised head design.
 
:
2010 CX-9 GT
So I went by the dealer yesterday to ge the rest of my stuff from my car. I spoke with the SA and was told that they’re only replacing the engine block, and that my powertrain warranty is the only warranty I get. I’m at 40k and will be around 43 months since the in-service date so there’s 20k and 17 months left. I recall someone else saying they got 12 months/12k miles but i think they were beyond their powertrain warranty. I’m not sure why, but I feel like that’s kinda insufficient. Maybe I’m just paranoid the service technicians won’t disassemble and reassemble everything correctly. Does this align with everyone else’s experience who’ve had this work done?


Are they replacing the "short block" or the "long block"? The long block is what they've typically been replacing in these cases - that includes the head.