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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: 10 26.3%
  • No

    Votes: 28 73.7%

  • Total voters
    38
Unfortunately. Mazda just keeps replacing engine for free, so no one has had the chance to put the effort in to find the root cause and solution to the problem.

(I am being sarcastic, i am glad mazda is doing this and taking care of their customers, but the side effect is that we know nothing about the problem).
 

sm1ke

Work In Progress..
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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.

Yes, could be, but to my knowledge the original part number already exists, and it has been revised with an added letter at the end of it (XXXA or something similar). Hopefully someone can confirm, but the part number with the added letter at the end might signify a revision to the already existing part.

There are still a lot of questions surrounding the issue and the proposed solution. Thankfully for almost all those affected, this appears to be happening within the warranty period.
 
:
2017 CX9 GT AWD
Thankfully for almost all those affected, this appears to be happening within the warranty period.
Still think that Mazda should publicly say that if this specific coolant issue happens they will fix it for free, even if out of warranty.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Yes, could be, but to my knowledge the original part number already exists, and it has been revised with an added letter at the end of it (XXXA or something similar). Hopefully someone can confirm, but the part number with the added letter at the end might signify a revision to the already existing part.

There are still a lot of questions surrounding the issue and the proposed solution. Thankfully for almost all those affected, this appears to be happening within the warranty period.
I thought your 2018 CX-9 also found some trace of coolant in the UOA report. Are there any updates on yours?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
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.
And from Mazda’s SkyActiv-G design, the engine block actually has 2 pieces (upper and lower) instead of one piece traditionally has. That is one of the reasons why IMO the front timing chain cover is prone to develop leaks.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Unfortunately. Mazda just keeps replacing engine for free, so no one has had the chance to put the effort in to find the root cause and solution to the problem.

(I am being sarcastic, i am glad mazda is doing this and taking care of their customers, but the side effect is that we know nothing about the problem).
I believe the reason why Mazda wants to collect all 2.5T’s which are having coolant leak issue is to research the root cause of the problem they may have not found yet.
 

sm1ke

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'18 CX-9 Signature
I thought your 2018 CX-9 also found some trace of coolant in the UOA report. Are there any updates on yours?

Yes, I sent another sample out after my most recent oil change a few weeks ago, but it seems that the lab may have misplaced my sample. I'm still trying to get that sorted out. I can report that the oil didn't look or smell contaminated, there are no signs of coolant residue my garage floor, and no coolant smell. The coolant level in the reservoir tank does fluctuate, but it hasn't gone below the L mark when completely cold. The level does appear to be lower than when I topped it up, so that would seem to indicate an internal coolant leak, which only a UOA would detect. So we'll see. I may have an "atypical" coolant leak issue.
 
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.
I called and was told they're replacing the short block. So based on their answer, that could imply I'm dealing with a different issue than the issues found in the head. Or the dealer I'm working with has no idea what they're doing.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I called and was told they're replacing the short block. So based on their answer, that could imply I'm dealing with a different issue than the issues found in the head. Or the dealer I'm working with has no idea what they're doing.
No, your coolant leak issue seems to be still consistent with others on your 2.5T. The leak is from “the back side (exhaust side) of the engine”, and it seems always on the cylinder block area based on few posts I’ve read. The difference is now MNAO (Mazda North American Operations) may have changed their practice paying more on labor to the dealer for cylinder block replacement, instead of replacing the entire engine on site. It could be the shortage on availability of factory rebuild engines, which may be caused by some parts shortage worldwide right now.
 
No, your coolant leak issue seems to be still consistent with others on your 2.5T. The leak is from “the back side (exhaust side) of the engine”, and it seems always on the cylinder block area based on few posts I’ve read. The difference is now MNAO (Mazda North American Operations) may have changed their practice paying more on labor to the dealer for cylinder block replacement, instead of replacing the entire engine on site. It could be the shortage on availability of factory rebuild engines, which may be caused by some parts shortage worldwide right now.
Thanks for the reply. I wasn’t sure the full details, and I’m not going to pretend to be super knowledgeable. I’m just trying to piece together if they’re doing the right thing. I guess at this point I’ll just try to bring my stress down a few ticks and enjoy the loaner until my car comes home.
 
Yes, could be, but to my knowledge the original part number already exists, and it has been revised with an added letter at the end of it (XXXA or something similar). Hopefully someone can confirm, but the part number with the added letter at the end might signify a revision to the already existing part.
I went back in this history for this thread and found @highfivezoom mentioned part number PYZ3-02-300D was installed by the dealer for his replacement. In another thread from another forum, I found PYY7-02-300L listed as the part used. When I looked up those parts, the 300L shows as the part number for a '16-'17 CX-9, and the 300D shows for '19+, but I can't seem to find details for what this part really is. Searches take me to various mazda parts sites, but they all just say "Engine Partial" or something like that.

Additional notes:
PYZ3-02-300D indicates that it replaces PYZ3-02-300, PYZ3-02-300A, PYZ3-02-300B, PYZ3-02-300C, so they're on the fifth revision of this part.
PYY7-02-300L indicates that it replaces PYY7-02-300B, PYY7-02-300D, PYY7-02-300E, PYY7-02-300F, PYY7-02-300G, PYY7-02-300H, PYY7-02-300J, PYY7-02-300K, thus making the ninth revision (at least, since some letters are skipped).

I don't know how to find the differences between the revisions, and I wouldn't be surprised if it's locked somewhere in Mazda's own repositories and we're left speculating what was done.

When I called my dealer and asked, they told me they're replacing the short block but didn't give me a part number. The repair with the 300L part had their invoice that stated they replaced the long block, so when I finally get my invoice from this, we may end up with a new slew of part numbers to add to this bag.
 

sm1ke

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I went back in this history for this thread and found @highfivezoom mentioned part number PYZ3-02-300D was installed by the dealer for his replacement. In another thread from another forum, I found PYY7-02-300L listed as the part used. When I looked up those parts, the 300L shows as the part number for a '16-'17 CX-9, and the 300D shows for '19+, but I can't seem to find details for what this part really is. Searches take me to various mazda parts sites, but they all just say "Engine Partial" or something like that.

Additional notes:
PYZ3-02-300D indicates that it replaces PYZ3-02-300, PYZ3-02-300A, PYZ3-02-300B, PYZ3-02-300C, so they're on the fifth revision of this part.
PYY7-02-300L indicates that it replaces PYY7-02-300B, PYY7-02-300D, PYY7-02-300E, PYY7-02-300F, PYY7-02-300G, PYY7-02-300H, PYY7-02-300J, PYY7-02-300K, thus making the ninth revision (at least, since some letters are skipped).

I don't know how to find the differences between the revisions, and I wouldn't be surprised if it's locked somewhere in Mazda's own repositories and we're left speculating what was done.

When I called my dealer and asked, they told me they're replacing the short block but didn't give me a part number. The repair with the 300L part had their invoice that stated they replaced the long block, so when I finally get my invoice from this, we may end up with a new slew of part numbers to add to this bag.

Thanks for doing all that researching, very helpful!

One thing I'll add is the possibility that some of those part numbers may not actually be revisions, they may simply be separate part numbers for different cars. The variations in part numbers could just mean that the engine assembly as a whole may be slightly different in terms of packaging (as is the case with the Mazda3 and CX-30 2.5T TMAP engine sensor location), but the actual engine components may remain the same.

You're right though, we may truly never know unless Mazda shines some light on this, or someone who has more insider knowledge about this issue joins the forum and reports on it.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I went back in this history for this thread and found @highfivezoom mentioned part number PYZ3-02-300D was installed by the dealer for his replacement. In another thread from another forum, I found PYY7-02-300L listed as the part used. When I looked up those parts, the 300L shows as the part number for a '16-'17 CX-9, and the 300D shows for '19+, but I can't seem to find details for what this part really is. Searches take me to various mazda parts sites, but they all just say "Engine Partial" or something like that.

Additional notes:
PYZ3-02-300D indicates that it replaces PYZ3-02-300, PYZ3-02-300A, PYZ3-02-300B, PYZ3-02-300C, so they're on the fifth revision of this part.
PYY7-02-300L indicates that it replaces PYY7-02-300B, PYY7-02-300D, PYY7-02-300E, PYY7-02-300F, PYY7-02-300G, PYY7-02-300H, PYY7-02-300J, PYY7-02-300K, thus making the ninth revision (at least, since some letters are skipped).

I don't know how to find the differences between the revisions, and I wouldn't be surprised if it's locked somewhere in Mazda's own repositories and we're left speculating what was done.

When I called my dealer and asked, they told me they're replacing the short block but didn't give me a part number. The repair with the 300L part had their invoice that stated they replaced the long block, so when I finally get my invoice from this, we may end up with a new slew of part numbers to add to this bag.
I believe either PYZ3-02-300D or PYY7-02-300L is the entire “new engine” for the 2.5T. That’s why the description says “Engine Partial”. Those are factory rebuilds by MNAO, and come with most essential components of the engine. The difference between the two could be from the different engine rebuilder. It’s like PY8W-14-302 and 1WPY-14-302 OEM oil filters both are for the 2.5T. But one from Tokyo Roki and the other from Denso.

As the revisions at the last alpha character on the same part number, it could mean many things. Like the OEM oil filters used on the 2.5L from factory, PE01-14-302、PE01-14-302A、and currently PE01-14-302B, they look totally identical from Tokyo Roki. Only Mazda knows their difference and what has been revised.
 

far4ngn

2016 CX-9 GT
My 2016 GT with 90k has been at the dealer for 2 months awaiting the arrival of a new engine. Luckily I had a third party extended warranty. The diagnosis for my failure is a warped head, but I suspect there is more to it with the whole engine being replaced. The engine was supposed to arrive last week, and there is no updated ETA at this point. My early discussions with Mazda USA boiled down to "good thing you have an extended warranty". This is my 2nd CX9 to have significant reliability issues. Our 2012 GT received 3 PTU replacements in 60k miles and it had a catastrophic radiator failure at 30k miles. There was a long list of additional smaller issues. The only reason I bought another Mazda was because I was offered employee pricing on the new one. Now I'm regretting that decision.
 
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sm1ke

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Yes, I sent another sample out after my most recent oil change a few weeks ago, but it seems that the lab may have misplaced my sample. I'm still trying to get that sorted out. I can report that the oil didn't look or smell contaminated, there are no signs of coolant residue my garage floor, and no coolant smell. The coolant level in the reservoir tank does fluctuate, but it hasn't gone below the L mark when completely cold. The level does appear to be lower than when I topped it up, so that would seem to indicate an internal coolant leak, which only a UOA would detect. So we'll see. I may have an "atypical" coolant leak issue.

The lab was able to finally locate my sample. Results aren't great. Potassium was reported to be high again.

I'll also report this in the UOA thread.
 
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far4ngn

2016 CX-9 GT
It was around $2k when purchased with the car. It is a 100k mile bumper to bumper warranty with no deductible. It was the first time I’ve ever bought an extended warranty, but I was worried specifically about the engine being a new design. The warranty has also covered some other more minor issues.