Poll 2.5T Coolant Leak/Engine Replacement

[arock712]

There are a few threads regarding the 2.5 turbo coolant leak problem and ultimately having to replace the engine. What I'd like to know is there anything that can be inspected and possibly fixed with this issue before it gets to the point of actually needing a new engine?

Edit:
I updated the thread to include a poll now of who is and isn't having this issue.

If you've had this done, please comment on the model year, how many miles you had when it occurred, when you first noticed the issue, if Mazda covered the cost under warranty, and any other details.

Also those with higher miles and no issues let us know how many miles so far.

 

[sm1ke]

I may be experiencing this coolant leak issue right now. Since filling up the coolant on Thursday, the coolant level in the reservoir has remained the same (checked 2-3 hours after engine shutdown). I suppose the leak could be slow enough to not register over a few days though. Anyway, I have an appointment with a local dealer to check for any leaks. When I have more info, I'll post it here and in my log.

 

[arock712]

I may be experiencing this coolant leak issue right now. Since filling up the coolant on Thursday, the coolant level in the reservoir has remained the same (checked 2-3 hours after engine shutdown). I suppose the leak could be slow enough to not register over a few days though. Anyway, I have an appointment with a local dealer to check for any leaks. When I have more info, I'll post it here and in my log.

How many miles do you have on it?

 

[sm1ke]

How many miles do you have on it?

About 33.5k mi

 

[PTguy]

Coolant Leak/Engine Replacement: What can be done to prevent?​

Buy a Toyota? Actually, if there is a weak spot in a gasket or casting there's nothing that can be done. Keep an eye on the coolant level and get to the dealer if there is a loss. Look for antifreeze puddles under the car where you park. It'll be the same color as the antifreeze in the plastic overflow tank and feel a bit slippery, not completely watery.

 

[arock712]

Buy a Toyota? Actually, if there is a weak spot in a gasket or casting there's nothing that can be done. Keep an eye on the coolant level and get to the dealer if there is a loss. Look for antifreeze puddles under the car where you park. It'll be the same color as the antifreeze in the plastic overflow tank and feel a bit slippery, not completely watery.

I just want this identified, somehow, before the warranty expires.

 

[edmaz]

You might want to try adding dye to the coolant - Tracerline 3900 or another specialty product designed to be added to coolant. Then, if coolant does leak from the pump into the oil, the dye would hopefully show up fairly quickly on the dipstick under UV light. If you decide to try this, and your vehicle is still under warranty, I suggest not telling your stealership about it - unless it actually does show up on the dipstick, and they try to deny there is a coolant leak from the pump.

 

[youri]

Different issue. I believe OP question is for the 2.5 turbo in 2016 and after. Not for the V6 engine that had the coolant leak from the pump issue.

 

[edmaz]

Different issue. I believe OP question is for the 2.5 turbo in 2016 and after. Not for the V6 engine that had the coolant leak from the pump issue.

When I read 'engine replacement', I automatically assumed this was a V6 pump-related question, because the normal worst-case repair for an overheat due to external coolant leak is HG replacement (perhaps including head resurfacing).

However, the OP didn't provide the engine, and it's not in the sig either, so you may very well be correct about that. And if this is a 4 cylinder being discussed, than IMO the OP should change the title, because engine replacement shouldn't be in that picture.

 

[arock712]

When I read 'engine replacement', I automatically assumed this was a V6 pump-related question, because the normal worst-case repair for an overheat due to external coolant leak is HG replacement (perhaps including head resurfacing).

However, the OP didn't provide the engine, and it's not in the sig either, so you may very well be correct about that. And if this is a 4 cylinder being discussed, than IMO the OP should change the title, because engine replacement shouldn't be in that picture.

I did put the CX-9 model years originally in the post, but I've edited the post to say it's the 2.5 turbo now.

 

[arock712]

Are there any TSBs regarding this issue? I found this one, but not sure if it's really related: https://tools.carmd.com/Tsb/Download/116402/TSB5700

 

[edmaz]

I did put the CX-9 model years originally in the post, but I've edited the post to say it's the 2.5 turbo now.

Ok, as I already posted, engine replacement isn't the concern with your 4 cylinder. Just check the coolant regularly (actually all fluids on all vehicles), watch for any (non-condensate) spots underneath on the ground, and monitor the heat gauge. Just do those simple and easy things, and you can relax and not get stressed out about this.

 

[sm1ke]

Ok, as I already posted, engine replacement isn't the concern with your 4 cylinder. Just check the coolant regularly (actually all fluids on all vehicles), watch for any (non-condensate) spots underneath on the ground, and monitor the heat gauge. Just do those simple and easy things, and you can relax and not get stressed out about this.

There have been a few reported cases on this site of coolant leaks that resulted in a full replacement of the 2.5 turbo motor. See here and here. It seems that in these cases, either a crack has developed in the head or there is a head gasket leak on the rear side of the engine. Either way, full engine replacement appears to be Mazda's preferred repair.

 

[edmaz]

Thanks for posting the links to those other threads which I somehow missed previously, even though I'm always actively on the lookout for systemic issues like this one. Although those threads did have a couple 2017 and 18 posted (including yours), this appears to be clustered around the 2016 model year. Seems like that old familiar caution about buying new products applies once again with this one.

Good to read however that Mazda seems to be doing the right thing by admitting to the problem and offering some measure of extended warranty coverage on these engines. Hard to understand though why the underlying root cause has not yet been posted yet. I guess Mazda is playing it close to the vest about that, as automakers almost always do with this stuff.

 

[sm1ke]

All I can say is that I plan to share as much information as I can from my experience. I have an appointment with the dealer today to get the car on a lift and see if they can locate the leak.

 

[edmaz]

In one of those threads you referenced, I recall seeing a post from you quite some time ago where you first suspected a coolant loss. How much coolant has your vehicle been losing over time? Have you ever seen coolant externally - perhaps on the underside panels? If not, then likely just a slow weep at this point? I'll be interested to read what Mazda says about your vehicle.

 

[sm1ke]

I don't think that was me. Normally I check the coolant level at every oil change, and its always been at a normal level. It seems to only have dropped recently. Even now, the car doesn't drip anything, and I don't think there is any indication of coolant pooling on the plastic panel that covers the oil filter. No odd smells coming from the engine bay either.

Maybe the leak isn't on the engine itself, but that wouldn't explain the high potassium reading from my last UOA.

 

[edmaz]

I don't think that was me. ....

Apparently that must have been another one of my senior moments

.... Maybe the leak isn't on the engine itself, but that wouldn't explain the high potassium reading from my last UOA.

Did you mention the UOA to them and, if so, did they give any indication of being willing to consider it as proof of an internal leak?

 

[Mazdiod2]

I've heard that a leak in the gasket can result in one of the pistons being much cleaner than the others, so sometimes checking ( remove the plugs) can reveal the leak.

 

[PTguy]

"...potassium has only one real major source when found in engine oil — antifreeze. Other key elements that you will want to look for are boron, chromium, phosphorus and silicon. All of these elements are associated with antifreeze and, if found in engine oil, can be an indicator that you have a coolant leak."
https://www.machinerylubrication.com/Read/29128/sodium-potassium-oil