2.5T Engine Coolant Leaking TSB

Moderator edit: This is a copy of a post originally made in another thread. This thread was created for easier reference.

Mazda recently put out this TSB for coolant leak because of cracks in the cylinder head.
As reported by many here it seems to affect the 2.5T 2016-2020 CX-9 as well as 2019-2020 CX-5 and 2018-2020 Mazda6
 

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  • TSB-01-013-21.pdf
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sm1ke

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I printed a copy of the TSB and s̷t̷u̷f̷f̷e̷d̷ ̷i̷t̷ ̷i̷n̷t̷o̷ ̷t̷h̷e̷ ̷c̷o̷o̷l̷a̷n̷t̷ ̷r̷e̷s̷e̷r̷v̷o̷i̷r̷ put it into the car. In case I get the leak I can go to a dealer, show the leak and the TSB to the service writer, and be believed. His need for diagnosis will be greatly reduced. The tech will look at the right place the first time, and they'll know what to look at and what to do according to the TSB I put into their hands.
 

yrwei52

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Moderator edit: This is a copy of a post originally made in another thread. This thread was created for easier reference.

Mazda recently put out this TSB for coolant leak because of cracks in the cylinder head.
As reported by many here it seems to affect the 2.5T 2016-2020 CX-9 as well as 2019-2020 CX-5 and 2018-2020 Mazda6
Although the TSB mentioned only cracks on cylinder head, but the fact is Mazda is replacing the entire engine (or long block) for the problem doesn’t add up. Some members even been told by the Mazda dealer that the crack is on the back side of cylinder block. Either there’re more stories haven’t been told, or there will be more TSBs coming out for this problem.
 
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NY
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2021 CX-5 Sig.
Although the TSB mentioned only cracks on cylinder head, but the fact is Mazda is replacing the entire engine (or long block) for the problem doesn’t add up. Some members even been told by the Mazda dealer that the crack is on the back side of cylinder block. Either there’re more stories haven’t been told, or there will be more TSBs coming out for this problem.
As ridiculous as it might sound, this likely makes the most sense from Mazda's perspective.

It's easier to swap the engine completely for any affected units as newer engine assemblies will have any updated block and head castings typically of later model manufacturing design corrections.

From a maintenance standpoint, it's also easier to have the dealer swap in the whole assembly rather than having block surfaces checked and corrected, timing reassembled, etc. Mazda likely wants these vehicles processed as quickly as possible to avoid consumer backlash.

We have similar practices in aviation. Helicopters, especially military, have Quick Change Assemblies (QCAs) including the rotor system, transmissions and engine(s) all removable as a single assembly. The QCAs can be "hot swapped" for component failures, life retirement, etc and overhauled separately to reduce maintenance downtime and overall maintenance costs.

Quick turnaround makes for happier customers.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
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Quick turnaround makes for happier customers.
Yeah, by letting CX-9 owners waiting for 2 ~ 3 months, even getting the whole engine from Japan after repeated phone calls and complaints. That’s the quick turnaround replacing the whole engine?

Read these threads:

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

2016 CX-9 Signature leaking coolant

On those 2.5L with cylinder deactivation, Mazda started with replacing the entire engine when the CD is having problrms such as fallen rocker arm or failing HLAs. Later Mazda created a new part number on cylinder head with everything pre-installed for easy replacement on cylinder head, and Mazda no longer replaces the entire engine for the same CD issues. No, replacing cylinder head has to be more cost effective everything considered if the cylinder block itself has no issues.

So it isn’t just the cylinder head cracked like the TSB says. Cylinder block may also be the subject easy to crack too. That’s my suspicion.
 
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2010 CX-9 GT
Although the TSB mentioned only cracks on cylinder head, but the fact is Mazda is replacing the entire engine (or long block) for the problem doesn’t add up. Some members even been told by the Mazda dealer that the crack is on the back side of cylinder block. Either there’re more stories haven’t been told, or there will be more TSBs coming out for this problem.

Aluminum heads and engine blocks warp slightly in use. Any time you replace a head gasket, you have to check the head and block for warping. If either is out of spec, that surface needs to be machined ("decked") to guarantee that the gasket will properly seal. Decking an engine block is typically done on a disassembled block (pistons, rods, and crank removed). This is not a quick or cheap process.

My suspicion is that Mazda can't confidently assume that the engine block is still in tolerance to make a simple head swap work. Additionally, there was a post on the forum that indicated that the engine needs to be pulled to do a head swap anyway, so it's probably faster and cheaper to just swap the whole engine than mess around with the head.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
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Plano, Texas, USA
-⋯ Additionally, there was a post on the forum that indicated that the engine needs to be pulled to do a head swap anyway, so it's probably faster and cheaper to just swap the whole engine than mess around with the head.
I saw that post and was wondering why the entire engine had to be pulled just to replace the cylinder head?
 
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2010 CX-9 GT
I saw that post and was wondering why the entire engine had to be pulled just to replace the cylinder head?

I'm speculating here, but it is probably because the engine block is too close to the side of the engine bay to get to the timing chain. You have to l get the timing chain off the camshafts to pull the head.

The old V6 is wedged in so tight that the factory service manual tells you to pull the engine to access the timing gear and water pump. From the photos I've seen, the new engine is in there pretty snugly, too.
 
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NY
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2021 CX-5 Sig.
Yeah, by letting CX-9 owners waiting for 2 ~ 3 months, even getting the whole engine from Japan after repeated phone calls and complaints. That’s the quick turnaround replacing the whole engine?

If you think this is only a Mazda problem right now then I'm not sure where you've been the last two years? 2 months is pretty quick right now for a whole engine assembly and it makes for a quick turn around when it comes in especially considering this still doesnt appear to be a significant number of vehicles just yet.

I'm looking at YEARS in lead time on bearings from SKF and Timkin so I'd love a 2-3 month wait. Forget about raw material for any forgings....
 

sm1ke

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Let's also not forget the size of Mazda as a company - its not like they can afford to keep dealerships well-stocked with replacement engines on the shelves the same way Nissan does/did with their CVT transmissions, for example.

In any event, we now have a published TSB that can be referenced by those who may be unlucky enough to have to deal with this issue. Regardless of the turnaround time, the issue has now been acknowledged by Mazda, and they have a plan in place to assist those who have the issue. We're in a much better position than we were a year ago.
 
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2016 CX-9 GS-L
Let's also not forget the size of Mazda as a company - its not like they can afford to keep dealerships well-stocked with replacement engines on the shelves the same way Nissan does/did with their CVT transmissions, for example.

In any event, we now have a published TSB that can be referenced by those who may be unlucky enough to have to deal with this issue. Regardless of the turnaround time, the issue has now been acknowledged by Mazda, and they have a plan in place to assist those who have the issue. We're in a much better position than we were a year ago.

We don't exactly get a separate or any Mazda Canada-specific TSB, right? :p
 

sm1ke

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We don't exactly get a separate or any Mazda Canada-specific TSB, right? :p

Not yet it seems, which sucks. But it's something, and providing a TSB that closely describes the issue that may be occurring on a Canadian vehicle is hard to write off completely, even if it's a US TSB. I would guess that we'll get our own TSB eventually.
 
I didn't see any mention of a special support program (extension of coverage in light of the TSB). Is this basically under the powertrain warranty or SOL?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
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Plano, Texas, USA
I didn't see any mention of a special support program (extension of coverage in light of the TSB). Is this basically under the powertrain warranty or SOL?
So far it looks like this. But some did get free engine replacement without powertrain warranty after contacted Mazda North American Operations.