Welcome to the forum

Not sure i*f you are asking question that can be answered at this point or just telling an interest and amusing story?

*If a question, then that can only be answered at this point with dissembling and expecting the engine.

 

LOL well my question is whether the PCV issues this engine has is the culprit, are the low
pressure rings to blame, and/or is the oil consumption like I witnessed normal for a high mileage 2.5.

I started out as an ASE Mastertech and Automotive Machinist in 1985, and was actually a Mazda Service manager about 20 years ago, and I'm curious about "known" issues with these engines.

I am the one who sold my family on how great the (non-turbo) 2.5 was supposed to be and Mazda made me look stupid. Being 3000 miles overdue for an oil change shouldn't have killed any mazda engine...

How else would a car that didn't smoke when starting or running burn through about 4 quarts of oil in 30 days in under 2000 miles? She was just over 1000 miles overdue when I added a quart that put her above the bottom mark on oil stick a month ago.

I know it would cost more time and money to fix than to replace so found an engine and need the old one for core, not gonna tear it apart... I am going to inspect the vvt valve later and keep it for a backup if it looks good and bench tests ok

 

the 2017 up to late production 2018 2.5 Skyactiv engines and transmission N/A are extremely reliable. There is NO abnormally known problem no more or less then any other platform generally speaking. Not sure where you are getting your info?
As you have the experience I am actually surprised that you did not find more clues to what happened?
As for service... we get perhaps because I tend to notice, about a dozen of the year range and model a year but never with the problems or for that matter production caused problems you have. Most is all lack of basic maintenance.
Just an FYI which really is meaning less but you did qualify yourself (appreciated) I have been and current ASE Master Technician L1 &L2, certified since 1995 prior ASE Certified Auto Mechanic since about 1982ish. lol Can't remember that far back for that. . Along with a lengthy resume which includes owning and operating a fully equipped Performance Engine machine shop with 3 Dyno's.

The only way which I know that you concluded at this point to satisfy your curiosity is tear down the engine. But some of what I suspect is from reading your first post what may have happened. The balance shaft assemblies on any engine do not like to be starved of oil. Your theory about the PCV valve is not realistic the engine would have smoked badly thrown several DTCs gone into limp mode and basically ran so badly just starting would have been a miracle. The intake manifold design could actually hod over a quart of fluid and just sit there.
I would be more suspect that the correct oil level was not there from long before the event that killed the engine took place?

Good luck and if you do tear down the engine I would love to hear what you found. You can PM me anytime if you prefer.

 

Well according to a random Google search a sticky or faulty pcv will cause oil consumption in a Skyactiv engine. I'm sure high rpms played a factor in burning excessive oil if that's the case.

alldata leans toward sticky pcv and high rpms

I only messed with it for 15 minutes at night. No check engine light, no oil either.

It had at least 3 oil changes this year they can remember at the dealer

The driver is a 24yo girl that dosen"t even look at her speedo or gas gauge (we have receipts to prove it)

But there are hundreds of people claiming the non-turbo 17 and ups are burning up to 2 quarts or more in 5000 miles or less, and there is definitely a problem with the 2.5t

So what is causing all of this oil consumption?

 

thanks for sharing

 

A faulty PCV valve can cause some low oil consumption when comparing miles and use of the vehcle but it will also cause a tailpipe to be black and the exhaust to have black smoke. And if the oil consumption from a bad PCV valve is severe enough the ECU would have generated a DTC because it is highly likely the IAT or MAS/MAP would have been contaminated with an oil film. Neither was indicated in the information about what was initially found?
And random google searches(the numbers have empirically been proven inaccurate regarding many subjects) maybe next time read them more carefully and see how they are worded and all the information concerning the issues being described before assuming they are supportive in any way to threads of concern on any forum thread topic. Most will have large gaps of missing information thus making them really less than the best to use as any example.
I might add if you have the full subscrition to ALLData then you are leaving out a lot of the information regarding oil consumtion and picked one that IMHO suited your questions. I use ALLData weekly for various reason most of which are labor hour recomedation between standard and warranty. My techs generally know what they are doing and know I follow up on all their work.
As for the other mention it was never shown to be a oil problem based on the number of production units. And the oil consution was from a so call suggested vale stem seal. Yet we have done the replacement seal on some of the engines in the TSB/VIN and found NOreal changes in the current seals to use for the service. We also found it strange some of the service bulletins regarding the parts number. But that is another subject and the only ones that could contribute real information would be a Mazda service employee, or someone that has many friends in the Mazda service department.
had a update to use

I do find it interesting that those random google searches NEVER have the individuals regarding a Skyactiv Mazda N/A engine mention what they found in the intake manifold.

I may also add that a simple scoping of the intake and combustion chamber can either identify or at least add some information about any oil consumption not to mention a simple leak down test which would make it close to conclusive.

 

The Skyactv engine has a common problem where the cylinder head develops a hairline crack and leaks oil. This happened to my daughter's 2020 CX-30. The Mazda shop had a very hard time finding it even though I told them going in to look for this. In fact they claimed it had no leak and returned it to us. Thirty miles later her check engine oil light came on and she had no oil on the dipstick. Long story short, it was returned to the dealer and the cylinder head was found on another inspection to be leaking oil. They replaced the head under warranty fortunately and no issues since. This is a well documented problem with the Skyactiv engine. Look carefully for any signs of oil leakage, like a puddle on the splash shield below the back of the engine.

https://bobistheoilguy.com/forums/threads/do-you-have-a-mazda-with-a-2-5l.368575/

BTW her car is non turbo so it can happen to either.

 

Well, does that suck.
Too bad to hear. I have a 2010 3i LF2.0. Just before skyactive

 

No it is not a "COMMON" problem with the Skyactiv engine and only effect a very few (based on total engine assembled over the time period) TURBOCHARGED engines.
I am authorized by Mazda USA to perform at any Mazda dealership or independent service shop in the USA warranty work of any kind (pre-authorized by Mazda direct) and have all the Mazda published information on the subject of the head casting concern. Not everything is published or accurately posted on forums especially the one last mentioned since new owners of took over that forum. That forum was once a great place for empirical facts and documentation now it is like most forum to many DIY posting repeated information that anyone can find on the internet and not really empirical in nature or complete information. Many thread topic's and information posted seems many members to try to support their responses. IMHO And yes i belong to that forum but seldom if ever anymore post on it.

Besides "D-3po".... this OP CARCOLLECTORS,..... IMHO based on his thread response has way more experience then you. LOL

 

Once again the resident blowhard gets triggered by anything I post. Of course it happens to non turbo engines! I have proof because it happened to my daughter's car WHICH IS NON-TURBO! And the word "common" does not mean that it happens to every car. Those of us with critical thinking skills know this, those who do not get easily triggered and have to spout off all of their credentials to try to impress people (which it doesn't).

To anybody that doubts me on this issue and wants to side with the resident easily-triggered know-it-all, just do this first: google "skyactiv cylinder head oil leak" . Now tell me who is right? Attached is a service bulletin PROVING that it happens to non turbo engines as well as turbo engines. Case closed.

 

Good to see some things haven't changed!

 

Off topic just like you!