By on July 29, 2013

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Evan writes:

Sajeev,

I have a piston slap question for a friend at work. She drives an ’11 Mazda CX-7 2.3. For over a year she has had an issue with fuel in the oil. Enough that the oil level has been as much as 1″ above the full mark on the dipstick as a result (oil level was checked after service, and frequently between services). This is noticed within weeks of service/oil change.

The issue seems to be worse with more short trips, and the car has been serviced as recommended by Mazda (or more frequent oil changes when warranty fixes attempted). The dealer has had the car repeatedly over the last year, and now continuously for over 2 months. They have replaced the HPFP 6 times as well as replacing the injectors twice. Leakdown and compression tests show no issues. Canada has no lemon law (just horrible binding arbitration), or the car would probably be a buyback by now.

The dealer has spent over 13k in repairs trying to fix it. They are at a loss, and Mazda forums haven’t helped, so I come to you and the B&B hat in hand. Also, even if they can fix it how much damage will so much fuel dilution cause? Should they demand and reasonably expect some sort of engine warranty extension?

Sajeev answers:

I am totally bummed to hear about your lack of Lemon Law-ing ability in this case.  O, Canada! 

I would seek more information on arbitration and contact Mazda Canada formally (AND via Social Media) to see if they’ll do anything. Sell this Mazda after the (possible extended engine) warranty expires…unless you’re thinking what I am thinking.  Ya know, an LS4 swap.

Mmm, LS4-FTW…that would be so awesome.

(cue harp strings, dream sequence) 

ls4shirtfinal

OH YEAH!  Front wheel drive…with BALLS!  Zoom-ZOOM-Zoom!

Ahem, now where were we?

Finding conclusive information on why fuel-oil dilution exists is tough via Google, but this SAE paper might contain the truth. Too bad I’m too cheap to buy it, too lazy to read and summarize for everyone’s benefit. Maybe some engineers with active SAE memberships can chime in here?

What say you, Best and Brightest?  Time to get a lawyer?

 

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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53 Comments on “Piston Slap: Inject Fuel Directly into…Oil?...”


  • avatar
    patman

    You’d think Mazda would want to buy it back just so they wouldn’t have to flush anymore warranty money down the drain on it.

  • avatar
    Windy

    One of the first autos with direct fuel injection was the M-Benz 300SL gullwing. from the early 1950s
    Gullwings require frequent oil changes and the dry sump system takes almost a case of oil. the reason is gasoline dilution which comes as a byproduct of the direct high-pressure fuel injection with not enough running hard and hot enough in modern traffic to drive the fuel out of the oil. esp in winter. My Dad had a gullwing from 1955 to 1980 and we changed the oil every1500 miles in cool/cold weather.

    since your Mazda is in canada is the problem worse in the winter time? have you tried blocking off part of the oil cooler if it has one or the radiator if it does not? checking the thermostat to see it is exactly within spec?

    I do not know how modern cars deal with this problem but we had to be sure to keep the revs up in winter to warm the engine quickly and never make short trips when it was cold to be sure the engine was run at full temp for no less than 30 min each time it was started.

    • 0 avatar
      lurlene

      Part of the dilution issue with the 300SL was the fact that it had mechanical fuel injection that would keep injecting fuel even after the ignition system was turned off and the engine was coasting to a stop.

      This is not the case with modern computer controlled DI engines.

  • avatar
    igve2shtz

    I have not kept up with the forums, but I have a Mazdaspeed6 with the same engine. Alot of us have installed oil catch cans to prevent oil sludge from making its way back into our intake manifold. When I drain the catch can, it has all sorts of liquids in it. When I allow the container to sit, the liquids separate, and there is clearly oil, fuel, and water and some other goodiness. I would have her go to the dealer and mention TSB 01-002/11 (if my google searches are correct). This is a Mazda TSB to cure the “smoking turbo” fix, but it also does alot to relieve the build up of crankcase pressures.

    EDIT: This is a post I found online – It is not my post, but similar to what I encounter:
    http://www.mazda3forums.com/showpost.php?p=7011876&postcount=14

    Another post from a different member – see last picture of the first thread: http://www.mazda3forums.com/showpost.php?p=6983646&postcount=1

    • 0 avatar
      IndianaDriver

      Does your DI Mazda engine sound like a sewing machine when started up in cold weather? I had a CX-5 next to my car last Winter at a hotel get started up and the sound was strange. Are other DI engines like this too in cold weather?

      • 0 avatar
        igve2shtz

        Yes – the chatter is common to DI engines, especially when cold. My co-worker has a SkyActiv Mazda3 that chatters on cold start up, and goes away when warmed. The MS6 has a low aubible chatter all the time. The forums say that it is from the cam driven fuel pump we use. I have yet to verify, but it seems plausible.

      • 0 avatar
        MBella

        The piezo injectors are really loud. We joke when we hear DI engine. Someone ask’s “Is it a diesel?” Someone else will respond, “It’s to loud to be a diesel.”

    • 0 avatar
      NormSV650

      I was thinking the same. Damn the emissions putting oil into our intakes!

      Might the owners short drives playing havoc not getting up to operatng temperatures.

  • avatar
    Mikein08

    Is it any wonder people buy and love their Hondas?

  • avatar
    DIYer

    Change the oil and filter every 3,000 miles. Use Shell Rotella T6 5W-40 Heavy Duty synthetic. If you keep fresh heavy duty oil in the motor, it will have enough service life to protect the engine even when diluted with gas. Also, keep the intake valves clean with Techron, Sea Foam, or Red Line additives. Good luck with your motor, if you keep everything clean it should longer.

    • 0 avatar
      NormSV650

      Got a point running diesel oil in a DI engine that is under severe service or short hauls. Though T6 lacks the friction modifiers of todays motor oils for mpg, I even use it in my wet clutch motorcycle where regular gasoline is to slick causing clutch slip.

    • 0 avatar
      patman

      Those treatments don’t do much of anything for the intake valves on direct injection motors since the fuel isn’t introduced until after the valve. That’s one of the common issues with DI motors – gunking up of the intake valves since they’re not constantly being bathed in parts cleaner like they are in a port or central injected or a carb’ed motor.

      • 0 avatar
        MBella

        Using seafoam or another intake cleaner sucked into the intake manifold will work. Putting something into the gas tank will only clean the fuel system.

    • 0 avatar
      Cirruslydakota

      Bingo. I have a 2008 Mazdaspeed3 and the first oil change I did after I bought it (5,000 mile interval) smelled strongly of gas. Just like with a diesel engine a gas D.I. engine is much harder on its oil and 5w-20/5w-30 PCMO (Passenger car motor oil) just shears too easily with these engines. So out came the 5w-30 and in went the Rotella T6 5-40 HDEO along with 3,000 mile change intervals. Besides the drop of about 1 mpg there have been no ill effects and the engine seems to like it just fine. The gas smell is gone and the oil has a nice dark amber color to it when changed. Also, with living in colder climates and short drives not allowing the engine to warm up compounds the problem. My old Dakota R/T would have oil smelling just like this during the winter since my commute to work was less than 8 miles.

      Also, any type of fuel cleaner is worthless on these engines with them being D.I. You have to remove the intake manifold and clean the valves manually with either strong alcohol or walnut blasting media. Google search BMW valve cleaning and youll see what I mean. On the Mazda MZR its caused by the EGR.

      • 0 avatar
        Pinzgauer

        My Juke is DI – Turbo. They spec 5w-30. I’ve been running only Penzoil Platinum for 55k miles changed at 5k intervals. No gas smell when dumping the oil and I don’t burn much of anything either. My driving is 95% highway though, with no short trips at all.

      • 0 avatar
        MBella

        A European spec 5W-40 oil will help with the fuel mileage drop vs. the full diesel oil, and will have most of the same benefits.

        • 0 avatar
          Cirruslydakota

          The Mazda MZR DISI engine should have been spec’d for synthetic oil from the get go, especially in the Mazdaspeed applications.

          Anyway, good point about Euro spec oil. However, I like the fact I can walk into any Wal-Mart (Don’t judge me, I only go there to buy oil and Ford filters!) or truck stop and pick up Rotella and be on my way. No searching around for Euro spec oil and a gallon jug, two extra quarts, and a Ford filter sets me back all of $43. I also run T5 in my 4.0 Grand Cherokee due to the non roller cam. Its good stuff and depending on your engine what you use may vary.

          Mazda had some issues with the K04 turbo smoking due to crankcase backpressure (Crappy PCV design.) and released a TSB changing the oil spec in the speeds from 5-30 to 5-40. It doesn’t help that I’ve heard of some dealer techs not paying attention and dumping in 5-20 which in this engine wont provide much protection against fuel dilution.

      • 0 avatar
        Mike

        You do read BITOG, don’t you :)

  • avatar
    gslippy

    This car needs a new engine (probably incorrect piston/ring/cylinder gaps), and a lawyer to help you get it. An engine swap would have been cheaper than what they’ve done.

    • 0 avatar
      Terry

      avatar
      gslippy
      July 29th, 2013 at 11:38 am

      “This car needs a new engine (probably incorrect piston/ring/cylinder gaps), and a lawyer to help you get it. An engine swap would have been cheaper than what they’ve done.”

      REALLY??? If the compression and leakdown are good, what will a new engine accomplish? You realize when you get an engine, you get the”long block”, meaning the block and head, oil pan, valve cover as an assembly. The engine control system, fuel system, and everything else from the original engine is transferred to the new unit. You dont get a complete “new engine”, or take one out and just put one in as-is.

      • 0 avatar
        gslippy

        Yes.

        It’s quite telling that the fuel components have been replaced 2-6x, but the block/pistons/rings have not been touched and yet the problem remains. I’m not convinced the leakdown/compression tests were correct.

        Moreover, if this is a design issue, you’d see it across the board on all 2.3s. I think he’s got a bad long block or head gasket, or MAYBE something wonky in the PCV system.

        • 0 avatar
          Terry

          0 avatar
          gslippy
          July 29th, 2013 at 3:01 pm

          “Yes.

          It’s quite telling that the fuel components have been replaced 2-6x, but the block/pistons/rings have not been touched and yet the problem remains. I’m not convinced the leakdown/compression tests were correct.

          Moreover, if this is a design issue, you’d see it across the board on all 2.3s. I think he’s got a bad long block or head gasket, or MAYBE something wonky in the PCV system.”

          Dont be convinced. This isnt a process of elimination, but rather one of diagnosis. Yo
          You say “Bad long block or gasket”, but if so..what’s “bad”? Neither component will put excess fuel into the crankcase. Even if that would happen, the air/fuel ratio sensor would pick that up as crankcase vapors are drawn into the intake manifold.
          Windy called it: Direct injection engines use high pressure–900-1855 psi, and if the fuel is not it burned will end up in the crankcase. Again, no codes, no check engine liught, no driveability complaints, yet you dont belive the compression or leakdown readings and would replace..”the engine”.
          You are the tech working on the car. You decide this situation calls for a new engine. Somehow the manufacturer approves the labor and parts, you do the work. A week later the same symptom appears. Tell me…what do you replace next? The manufacturer receives the old engine in warranty, does a teardown, and finds nothing wrong. They then decide to debit the dealership for $7K in the parts and labor they paid. Who pays the dealership back–you, the mechanic?
          Define..”wonky”. And if there is a PCV issue, they why would you replace the engine?
          Point is.. I can guess, hypothesize, estimate, use my 40 years of automotive experience(32 w/Mazda), but unless I perform a diagnostic path, I can’t possibly know what the problem is, or even if there is a problem in the 1st place. Can you?
          In my job, before I can replace a part I have to prove the old one is defective. In my shop customers and manufacturers dont pay for guesswork.

          • 0 avatar
            MBella

            You are right Terry. There is no way this issue could be caused from any fault in the long block. There are only two places where fuel could mix with oil directly. The injectors,and high pressure fuel pump to camshaft area. That has been addressed several times, and I am out of ideas. Maybe a software or wiring issue causing the injectors to leak a bit?

  • avatar
    danio3834

    Don’t poo-poo the arbitration, it can get you results. I would suggest you contact CAMVAP to discuss your options since the dealer and Mazda seem to be having trouble making good on their warranty.

    Regarding the fuel in the oil, yes, oil dilution will cause premature engine wear issues as gasoline is not a lubricant in any sense of the word when it comes to engines. Oil growth is common in diesel engines due to the regeneration cycle that injects fuel on the exhaust stroke. That comes with it’s own set of problems, but diesel isn’t nearly as bad to the bearing surfaces as gasoline. Since this is a gas motor, you likely have a leaking fuel system component if compression is to specification.

    It is important that this issue be addressed. My first thought would have been leaking injectors, but as I am not familiar witht he exact construction of this engine, I’m not sure what other parts of the fuel system can leak into the crank case. I would suggest talking to Mazda customer service, and if they are unable to get any results for you, contact CAMVAP yourself to get a resolution.

  • avatar
    SpeedJebus

    I did a bunch of research on possible buyback options when I was having repeated issues with my 3.8l on my 2011 Wrangler. CAMVAP can actually kick in within the first two years of ownership. Definitely look into it as previously mentioned. It’s a solid option!

  • avatar
    Terry

    As a Mazda Master Tech several things here bother me: Why 2 sets of injectors and 2 high pressure fuel pumps?
    If the engine were running that rich there would be several other issues, such as a check engine lamp and fuel trim codes, possible catalytic converter damage and resultant code, excessive fuel consumption, and bent connecting rods from leaking injectors upon startup after a heat soak.
    Compression appears to be good, as does leakdown.
    Using the Mazda IDS diagnostic computer, parameters such as fuel pressure(as high as 1885psi on this engine), fuel trims, air/fuel ratio readings can all be monitored. Which has me asking how this issue is being diagnosed in the 1st place.
    Note that the only complaint in fuel in the oil. Not a driveability issue, excessive exhaust smoke, poor mileage, no check engine lamp.
    It was mentioned that this occurs during short trips. The customer needs to define what she means by a “short trip”.
    In the Mazda DISI 2.3, frequent short hops can have unburned fuel run past the piston rings and get into the oil. Driving to full operating temperature will have the fuel, vaporized at this point, pulled into the PCV system and burned along the injected fuel.
    So…is this really a problem? Besides what is seen on the dipstick, are there any real issues here?
    To date, with all the Turbo CX-7s, Mazdaspeed 3s,and Mazdaspeed 6s I deal with every day, I have yet to have an engine mechanical problem other than 1 Mazdaspeed 3 which had the injectors leak down and and 2 connecting rods. 2 new rods and 4 injectors later, issue resolved. But the complaint was a vibrating clutch pedal, not a high reading on a dipstick. No piston ring or crank bearing problems seen with these cars, and we are a high-volume dealer.
    Engine noise was mentioned–and I do see timing chain problems on cars whose owners have been lax with maintenance. The Mazdaspeed3 and Mazdaspeed6 vehicles dont seem to have this issue as their owners are more into maintenance than most CX-7 owners.

    • 0 avatar
      Windy

      One of the best features of TTAG is the way you get real experts on a topic like Terry to help with a problem.

      Folks like myself with owners perspective, perhaps augmented with the skills of a shade tree mechanic, can take you only so far…. Of course I would be fibbing if I did not notice that Terry has also zeroed in on the short trip comment from the OP.

    • 0 avatar
      WheelMcCoy

      As TTAC regains its footing, I see the quality of the comments improving. Thanks Terry for your experience and insight.

      So the best cure for the car and owners is a family road trip! Preferably southward toward warmer climes. And if I know my Mazdas, hit the redline once in a while too.

    • 0 avatar
      sportyaccordy

      Do you count gunked up intake valves as a mechanical problem? That seems to be a given with all DI engines including Mazdas

    • 0 avatar
      jadnhm

      Great comment. Thanks for weighing in Terry. Experienced folks make a big difference on boards like this.

  • avatar
    kmoney

    Don’t know what province you are in, but you may have other options. In BC this would fall under the Sale of Goods act, and the non-functional engine violates several of the deemed conditions of every sales contract.

    https://www.cba.org/BC/public_media/credit/257.aspx

  • avatar
    mfgreen40

    He could of said “have”, but must of forgot #1 I love it.

  • avatar
    Beerboy12

    It’s possible oxygen sensors are not functioning correctly. That might not show up in engine diagnostics and hide over rich cold start mixtures. That is very hard to diagnose and would cause theses symptoms.

  • avatar
    manbridge

    Is this some Jalopnikesque WTF post of the day?

    Seems a simple math problem. It is currently 2013. A TWO year old car should not be suffering from such calamity, short trips be damned.

    Step one. Find an attorney.

    Step two. Buy another brand of car with settlement, preferably a VW bug as that is all original poster will be able to afford with what is left.

    What a flustercuck.

  • avatar
    bludragon

    OK, this might be a dumb question, but how do you know there is fuel in the oil? Did you get an oil analysis?
    Are there any other symptoms besides a high oil level?

    First thing I would do is not to believe a word this dealer tells me.
    Then I would independently get a used oil analysis.
    Based on that I would go visit a different dealer, or follow up with Mazda directly.

  • avatar
    Terry

    Funny how this thread turned from one of a mechanical issue to one of litigation and “Let’s get the lawyers involved.”
    1st–what “calamity” are you talking about?
    2nd–is there a mechanical issue?
    With all the 2.3 CX-7s that visit our shop daily, NOT ONE has complained of oil dilution or a high oil level. Not one has suffered ring wear, not one has had a problem with main or rod bearings.
    So…what actual problem is this vehicle having?

    • 0 avatar
      greaseyknight

      Totally agreed, what this vehicle needs is a skilled tech who is very skilled in diagnoses. Way to many parts changers out their, and not enough problem solvers. I mean, 6 HPFP’s? the first one may have had a small amount of merit, but after that its just pure lack of skill. Have he seen any of the video’s on Youtube from “ScannerDanner”? The guy is awesome teacher and automotive problem solver, highly recommended, even to just understand whats going on under the hood.

  • avatar
    claytori

    It seems to me that there may be a fuel control problem during the warm-up. Remember that the engine runs open loop for this period, so there is no O2 sensor feedback and if running rich there would be no codes. This could be tested by using an exhaust gas analyzer from a cold start. If so, then the cause would need to be determined. We know that the injectors are not the problem, but how are they controlled? An oscilloscope in the injector firing circuit could determine the on/off ratio and this should be compared to the specification.

    Instead of the EGA you could try using your nose. There would be a distinct unburned fuel odor from this at the exhaust pipe.

    Edit – A thought cam to me as I posted this. Is it possible for there to be a defective recess in the cylinder head where the injector fits in? Say there is some bad machining that is allowing high pressure fuel to be sprayed back around the injector body into the oil galleries in the head. Long shot I know, but this is a very rare one.

    • 0 avatar
      Wheeljack

      The catalytic converter wouldn’t last too long with that much fuel being dumped into the exhaust. I think the real issue and noted by other posters is the short-trip driving. The same issue occurs on HPCR diesels that have a DPF and/or a NOx adsorbtion catalyst that are driven on short trips without a proper warm up.

  • avatar
    Terry

    Claytori, not true.
    This system uses a front air/fuel ratio sensor, not a regular zirconium oxygen sensor as used in years past. The air/fuel ratio sensor requires no warm up, hence fuel control is almost immediate. The old 02 sensors required 600 degreesF to begin feedback and change the control system into closed loop. Fewer emissions during warm-up was the goal. The A/F ratio sensor signal is in amperage, not voltage as with the 02 sensor. The rear sensor is an 02 and is used to monitor catalyst efficiency.
    The key thing to remember is that there are no codes present, no complaints of exhaust odor, no complaint of poor fuel economy, and no driveability complaints. In short, NO REAL PROBLEM other than what is indicated on the dipstick.
    Greasyknight, what ScannerDanner does in his Jr College is what Ive had to do for years in dealerships–advanced engine,emission control, and electrical/electronic diagnosis using scanners, multimeters, and labscopes. When your customers rely on you for diagnosis to save them time and money, as a tech, “you dont bring a knife to a gunfight.”

    In a conversation about this issue with one of my Mazda service personnel, we both agreed it is entirely possible that under certain driving circumstances(short trips, short-hopping) a raised oil level with fuel odor is a characteristic of this engine.
    But..with this CX-7, there is no flooding, no missfire, no driveability complaints, no check engine light or codes. So, again…is there a problem? If it werent for the high oil level on the dipstick, would there even be an issue?
    All the engine operating parameters, sensors, voltages,, in short the complete engine control system can be viewed via the Mazda IDS computer.
    2 sets of injectors and 6 high pressure fuel pumps….if this isnt a red flag for more intensive diagnosis, I dont know what is.
    IGVE2SHTZ–I have done MANY of the DISI engine crankcase ventilation kits. They work well. The Skyactive clatter when cold is a normal characteristic of this engine, but the noise can be reduced via an engine control unit update.

  • avatar
    Athos Nobile

    I got the paper. To make the story very short, her driving habits are making a condition, which seems normal to every car, worse.

    Tell her to drive the car longer so the engine work for some time “hot” and it can evaporate all the fuel diluted in the oil and burn it.

  • avatar
    william442

    My Fairbanks Morse diesels had this problem.. Never solved.

  • avatar
    bigev007

    I know I’m late to the party to be replying, but have some follow up on this. The dealer agreed to a buyout and an excellent price on a CX-5. I don’t know the exact details, but it seemed to be an extremely generous offer. My co-worker is very happy with the CX-5 so far. I hope she remains so. I feel bad for whomever ends up with her old car.


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