Engine toast due to freeze plug?

Okay... First, thank you all for what you do talking with one another... Second, hope you are safe and healthy. Third... Ive had a couple cocktails...

I am so damn pissed that my 2011 CX9 engine is toast because of an irreplaceable front freeze plug??? WTF!!!! How can a simple freeze plug not be replaceable! How do you need a new replacement engine??? And with the whole water pump fail-issue, how the hell do you tell the difference between the weep hole and the freeze plug which are just millimeters apart? How can it be that a freeze plug (if that's what it is) cannot be replaced? Can it be taken to a machine shop? Custom part? What the heck! This is crazy.
Ottawa, Ontario
17 Mazda 6 GT
So why exactly is your engine toast?
What's the problem/symptom?
Did a qualified mechanic troubleshoot a problem and tell you that it's toast?
Some clarification would be helpful.
Yes, more detail necessary. There was a pizza-sized puddle of antifreeze on the garage floor right under the alternator, on the passenger side of the car. I thought the worst and believed it was the dreaded internal water pump issue, so I took it into the local Mazda dealership where we have all of our service performed. They have been awesome over the years. I expected them to report that they would need to pull the engine/perform the invasive surgery to replace the water pump. They looked at it closely, removing the alternator and using a flexible camera to investigate the source of the leak. based on the camera evidence, they said that it was not coming from the usual tell-tale spot of the weep hole that signals the bad water pump issue, and no signs of antifreeze in the oil, but just adjacent to that, which is the freeze plug. The service manual for this specific engine (long been in service for ford and Mazda) states that the freeze plug is not a replaceable part and that the only solution is a new engine. They said the good news is that I didn't waste my time and money having the water pump replaced as that wouldn't fix the problem.

So long story short, Dealer, ASE certified mechanic, camera evidence, not the water pump, but the freeze plug that cannot be replaced.

How can a $100 dollar part (on most other cars) necessitate the replacement of a whole engine, that by all other casual measures, runs perfectly?
Ottawa, Ontario
17 Mazda 6 GT
I'd suggest more investigation before springing for a new engine.
Try posting the same question and information on a Ford forum.
Get a second opinion at a different dealer/garage maybe as well.
I've read up on this water pump issue quite a bit, only because I've been considering buying a used Explorer (I don't have a CX-9).
I checked a few Ford forums and found them very helpful.
There was never any mention of a freeze plug problem on the forums I checked, so unfortunately I can't speak of it with any knowledge.
Keep us posted.
Good luck.
if it was the water pump it would not leak on the floor but in the engine oil which you could not see unless you check your oil.

First time i hear about the freeze plug but i would try and get t fixed. If it is in a bad spot you might need to get the engine removed. Mazda doesn't have anything listed for this so the only thing you can do is change the engine. They won't start to try to do a hack job or try to fix something that is not usually fixable (for exmaple if a weld in a ECU is bad, they won't do the weld, they will charge you 1000$+ to change the ECU.) Fixing the weld takes 5 minutes and will probably last as long as a new ECU but you need to find an independant shop that is ready to do the search and the fix.

Same for that plug, once the measurements are taken, i am sure a good shop will be able to find one of the same size and install it. Dealership won't do it if it is not in the manual.
Thanks for the suggestions! If I do decide to pull the engine and fix the freeze plug, I’m going to replace the water pump too. No sense to go that deep and not make a few maintenance repairs!!!!! I will keep you posted.
92 MX-3; 18 CX-5
The freeze plug, core plug or expansion plug- whatever you want to call it is replaceable. The plugs can’t be more than a few $ each. The only thing I can think of is that it is impractical for the shop to do the repair because of what they would have to charge. Maybe due to the location the engine must be pulled. Also there is more than one plug so do you replace them all?
This is too bad because the water pump can be replaced with the engine in the car - at least for the CX-9. I wonder if it is possible to make enough room to replace the leaking core plug with the engine in the car. It sounds like you might find out. Good luck with your repair.
I stopped at a buddies today who has a flexible camera (endoscope) and took this picture. Sure looks to me like it’s the weep hole!!!! The dealer showed a similar picture, but it doesn’t even look like the same engine!!!! The first pic is my buddies camera. The second with the orange scope screen is from the dealer.

92 MX-3; 18 CX-5
Very good. The core plug looks solid - not obviously corrosion that it would leak. And you may be lucky to have a water pump gasket leak that is leaking external. The water pump has 2 rubber o-ring style gaskets and can leak past the first one into a channel that will direct the coolant to the weep hole by the alternator. The more insidious leak is past the water pump shaft seal and into the oil. Or both gaskets leak so the path is again into the oil.
It’s a big DIY job or a big bill with the shop but I think this is a failed water pump-just a little unusual leak exclusive to the gasket seal.
2010 CX-9 GT
The Mazda and Ford part database lists the freeze plug as unavailable - not serviceable. That's why the dealer told you it can't be replaced.

My guess is that you can probably pull it and replace it, but I've not been able to find any "internet evidence" that this has been done before. I have found a couple of examples of people thinking the freeze plug was leaking, but it turned out to be the weep hole from the water pump.

Good luck. Let us know what you find.
Thanks again all. I've been studying the DropBox documentation on the water pump install and think that I can handle it with a buddy. He's replaced half a dozen timing chains on late model overhead cam engines and thinks this is doable. I'm working on ordering the parts now. It will be a few weeks until we get to it but I will document it and get back to you.

On the parts listed in the PDF document, I'm seeing discrepancies when I look for my MY 2011 CX-9. HOWEVER, if I type in the exact part number in the document, it says it fits! I think I will call the dealer I'm getting the parts from and talk through it to be sure I have the right ones. I'm worried there could be minor differences between 08 (the OP's car) and the 2011 (mine).

I don't feel lucky yet, but I know what you mean! LOL
Well well well. With hat in hand, I must tell you all that I have FAILED! I attempted to do the water pump replacement with a friend of mine. We made awesome progress working together and getting this thing torn down and put back together. We did it all in about 12 hours on Saturday. We fired it up and it was singing the worlds sweetest song! We high fived (even full contact in these Covid-days) and cracked some beers as we watched to coolant level to be sure we added enough. Perfect! We cleaned up and I drove him home in the Mazda. It was running great. When I restarted the car at his place, the check engine light came on. We were dumbfounded.... Being tired, we said goodbye and lets look at it tomorrow. Next day he comes over with his code reader and we saw that bank 2 was throwing a crank/cam out of phase warning. How could that be??? It ran so well! Did we tweak a sensor???? We decided to give it a test drive, and after yesterdays ginger beginning, we gave it some load.... BAD! It began missing almost immediately. Even died on the side of the road. We limped it back home and began tearing it apart again double checking everything. Turns out we were out of phase by a tooth, maybe 2!!!!! We re-adjusted, buttoned it back up, and fired it up ohhh about an hour ago. I’m sad to report that the engine is now making a knocking noise severely. Not showing any codes or check engine lights to speak of, but as soon as you put it under load it sputters, misses, and dies..... I fear we have a broken rod with all the racket it’s making now... JUNK!... If the engine wasn’t toast before, it is now. I will post some pictures later to be sure nobody else out there makes the mistake we made! Clearly going back, we misinterpreted a mark on the engine casing. So heartbreaking as we had this NAILED! The internet is full of weekend hero’s telling of their victories, and I enjoy them as much as the next person. This here is a FAIL. Almost that is... The car no longer leaks a bit. It was never the freeze plug. It was always the water pump. We got that part right. I wish now I would have been wrong. I wish now I would have just traded the car in for the 500 bucks they offered me.... Later folks! Be careful out there! Sometimes there isn’t a happy ending.
wow that sucks, thanks for the feedback, this is not an easy job. Lesson learned i guess for the next time... Don't let that discourage you from working on your own car, when you do it right, it is very gratifying.

On an other note, i don't see how it could have bent a rod, maybe you have some croocked valves as they might have hit the piston but i doubt that would bend the rods. I could be wrong but i suppose the valves are weaker that the rods. Maybe taking the heads off? Or trying to see where the sound is coming from with a stetoscope?

Was only one side of the engine off or both sides? If it is only one side than maybe you just need to fix that particular head.
The cams for both sides were still in phase with one another. We were off on the crank, so both heads could be damaged, though it really sounds like the noise is only coming from the middle or furthest to the right on bank a (I believe this is cylinder #2 or #3. We compression tested before we tore into the whole re-rebuild and the numbers were decent. 152psi High-146psi low. Do you think you could see a bent valve with a bore-scope? I used one to help confirm TDC on the 2-nd try and could see the intake valves just dropping in, but I couldn’t see the exhaust valves... Man, we are bummed. We have had a lot of success with other timing jobs in the past... We were likely working too fast and too late, and got confused by a mark on the engine casing and assumed TDC based on that value, not on actual inspection!!!! I will post pictures soon.
Here is where we went wrong. 74421890-C802-408F-8FA2-D7A161A02A82.jpeg 9D2AB70D-53F6-4CAE-9D7E-072E7DBD2BDF.jpeg

On our first attempt we aligned the timing mark on the crank with the groove at approximately 5 o’clock. This put the crank key-way at 12 o’clock. We missed that. The big ol groove just seemed an obvious timing alignment mark that we adjusted to fit that as best we could, which in turn ate the motor.... Or more likely bent a valve as puma says above.
92 MX-3; 18 CX-5
Wow - very happy to hear that the issue was the water pump and very sad to hear of the outcome of your hard work.
When you take on a big job like this, sometimes you fail. Ask me about that time it took 3 attempts to install a rebuilt engine. Or the time I installed a rebuilt transmission but did not properly seat the new torque converter.
I've done a bunch of big jobs and learned a lot in the process. Sometimes by failing. The 3rd engine I installed ran for 90K miles before I sold the car. The transmission required a new torque converter a thorough fluid flush and redo - but lived to drive again.
Maybe after a couple of days you can consider a next step. Used cylinder heads, rebuilt heads or a used engine could get you back on the road again. You guys definitely have the courage and skills to recover from this mistake. I'm blown away that you completed the job in 12 hours. 12 hours was about 1/2 way done with the water pump job I did on a 2008 CX-9.
Thanks Davmac. Neither of us are mechanics, but both have spent time under the shade tree if you know what I mean! We have also worked together on a large number of construction projects, so we know how to work with each other. We were humming along! And loving life! That to me is the big win here. We started with what the dealer said was a lost cause... We felt different and were right... That is up until our mistake. But hey, we learned, and had a ton of fun. I agree with you too, this isn’t over, we might just be a weekend or two away from another tear-down. Whatever it is doing sounds bad, but cannot be THAT bad. It starts right up and idles fine. The noise even now seems to be getting quieter??? I really believe it is valve-train now.

Wouldn’t it be awesome to jump back into the fray and get this thing right???! I don’t think I’m ready to give up, though I do have a bit more wound licking to do! Thanks all!