By on September 22, 2014

sleep. Shutterstock user Alena Ozerova

TTAC commentator markholli writes:

Hi Sajeev,

I saw your call for reader questions for the Piston Slap series, and as a diligent and loyal TTAC supporter/Kool-Aid drinker, I will do my best to do my duty (did I just recite the Boy Scout motto?).

You’ve been kind enough to respond to my previous question regarding the failing health of my wife’s Subaru Outback. By the way, in the spirit of CarTalk’s Stump the Chumps question follow-up feature, we ended up dumping the ailing Outback via Craigslist at a discounted price with a full-disclosure of all the mechanical issues (Love. It’s what makes a Subaru a Subaru…or something like that…). We got a 2nd gen Acura MDX and we actually love it. Take note Subaru.

Anyway, to my question: my daily driver is a 2007 4Runner with the lovely Lexus-derived 4.7 V8. The V8 part is important because in the 4×4 variant, as mine is equipped, the power is delivered to the road through a full-time 4-wheel drive setup, rather than the part-time 2H-N-4H-4L system found in the 4.0 V6 4Runner. We’ll come back to that in a moment.

Now, for a story about babies–don’t worry, I’ll tie this all together. Last October the newest addition to our family was born. He’s a super cool dude, and we love him a lot, but he has never been a good sleeper. Even now, 9 months in, he is easily stirred from his nighttime slumber, and usually isn’t happy or easy to put back to sleep when awoken.

As it happens, both of our children’s bedrooms sit right above our 2-car garage, and unfortunately we discovered after moving into our home that sound insulation was pretty low on our homebuilder’s list of priorities (priority #1: make lots of money!). Pair this with the fact that I leave for work in the wee hours of the morning, and the fact that the 4Runner makes a loud roaring noise when fired up, and you see the problem.

To prevent my early morning departures from upsetting the oh-so delicate sleep patterns of the baby, I have started popping the 4Runner’s transmission into neutral and then rolling the car backwards down the 20 foot driveway into the street, where I can safely start it up. My question is this: is this little insane routine of mine causing damage to my drivetrain?

Because it’s material to the discussion, I will note that the full-time 4-wheel drive system and transfer case cannot be shifted into neutral. Thanks!

Sajeev answers:

How dare you reference Subaru’s Love-Centric marketing campaign for an Acura MDX?  The fanbois are gonna raise up the “TTAC’s Anti Subaru Bias” flag because these whips are the best thing for you and your family and HOW DARE YOU love an Acura MDX like an Outback?

Now to the 4Runner: odds are the initial kick of that heavy-duty, big-ass finned aluminum clutch on your cooling fan is what howls/growls loud enough to upset the little one resting above the truck. Too bad about that, but hopefully the problem solves itself as he gets bigger and less of…well, less of a baby I guess.

Are you causing any damage by rolling down the driveway, 20 feet a day?  This question is much like flat towing a car (especially behind an RV) with one difference:  20 feet ain’t no thang.  If you’re still concerned, change the drive line/transmission fluids to fresh and fully synthetic oils (if not already) so you’re ensured the good stuff splashes around when you fire the 4Runner from a dead cold start.

20 feet every week day until he gets old enough to not care about a whooshing fan clutch?  Totally not worth worrying about: off to you, Best and Brightest.

[Image: Shutterstock user Alena Ozerova]

Send your queries to [email protected]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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65 Comments on “Piston Slap: Sleepless Above The 4Runner?...”


  • avatar
    PrincipalDan

    Re: the meme above. Yes I know that face and that conversation.

    Bonus question for the B&B, can someone explain how Toyota’s full time 4wd system works? I’ve got a 2010 Highlander with the 50/50 front rear torque splitting system and I can’t find anywhere online a detailed description of how it works. I’m a gearhead and I’m just curious.

    • 0 avatar
      gtemnykh

      If I’m not mistaken, the Highlander has a “typical” for a CUV setup of a viscous coupling going to the rear axle, and this can be electronically locked for that 50/50 split. However, under hard, sustained use these coupling overheat and decouple, leaving you with fwd. They are also not instant in their response, however they are getting quicker with every new generation. I believe both Toyota and Honda have the coupling route some power when taking off from a standstill, no matter the traction situation.

      The 4Runner most likely has an open center differential that can be locked on demand. This is a sturdier and more no-nonsense system in that it split torque all the time and is a hard mechanical lock so it won’t overheat and quit. But this also weighs more and has more driveline drag (worse mpg).

  • avatar
    djsyndrome

    “We got a 2nd gen Acura MDX and we actually love it. Take note Subaru.”

    Acura 15,487 17,051 -9.2%
    Subaru 50,246 41,061 22.4%

    What, pray tell, should Subaru be taking note of?

    • 0 avatar
      TEXN3

      Like the OP and me, they’ll eventually discover they’re unreliable family transportation. I had a 2007 Outback 2.5i MT, great for tight trails but a nightmare in the shop (bearings, reared, alternator, head gaskets) and sucked on the open roads of the mountain west. At lest I had the foresight to get the extended power train warranty. We went back to Honda and got an Accord, as well as company issued pickup. Accord with x-ice2 does just as well on the snow as the Outback. I do miss having a manual. Due to the Subaru koolaid drinkers, I made $2k over kbb value with full disclosure on work done.

    • 0 avatar
      markholli

      Not sure what it proves to cite sales figures. By that logic we should all be driving Corollas and F-150s.

      I guess my point is that everybody who owns a Subaru long enough will eventually tire of replacing CV axles, hubs, clutches, timing belts and, most of all, head gaskets.

      But I suppose it’s a moot point, as our culture of conspicuous consumption drives people to replace cars every 2-3 years, long before the issues arise. Most Subaru owners probably buy a new Subaru after the warranty expires on the previous one and drive problem-free for another 36,000 miles or whatever.

  • avatar
    raresleeper

    Hmmmmm. MDX, eh?

    Friend of mine has a first gen. It’s about to reach that 200k mile mark and is quickly achieving cockroach status. He doesn’t see it quitting anytime soon.

    Will the 2nd gen MDX wear that crown? Too soon to tell.

    Lol. I do find it amusing that people go to these extreme lengths at the risk of making too much noise.

    Our garage door opener is noisy as hell. The start-up 3.5L M276 engine in the ’11 GLK isn’t exactly whisper quiet, either (don’t get me started on the other cars start up noises). Plus, our home, being built in 1973, lacks sound deadening, as well.

    But our garage is directly under the master bedroom, not our kids’ rooms.

    Lol. Good luck with the baby.

    Alert the Subaru Fanboys!

  • avatar
    Quentin

    My wife has accused the TRD exhaust on my FR-S of waking the 2 year old.

    Oh well. Her MCS is just as loud. The garage door opener probably wakes her as much as anything.
    ¯_(ツ)_/¯

  • avatar
    -Nate

    This is funny because Humans are *infinitely* adaptable to anything .

    My Son learned to just go back to sleep , it’s normal for a Baby to wake up and howl a bit , unless you’re a ‘ helicopter parent ‘ dead set to make your Child insecure and afraid of everything in life , just skip the night lights , worrying so much etc. , he’ll be fine , Nature has been taking care of babies since time immortal .

    *VERY* cute kid BTW .

    -Nate

  • avatar
    ckb

    An electric fan conversion would cut down on start up noise. You can DIY for under $150 if you like chasing wiring in the engine bay. The fan won’t start spinning until the coolant is up to temp (or maybe not at all) which will get rid of the startup roar. Plus you’ll get back a HP or so and increase your mileage by a tiny amount. Win win win!

    • 0 avatar
      TR4

      Not so simple to do it right. If the vehicle has A/C, the fan should be running whenever A/C is on, otherwise the high side pressure will skyrocket and shut the system down.

      • 0 avatar
        anti121hero

        I hardwired the aux fan in my jeep. It comes from the factory with a mechanical and electric fan, and the electric fan kicks on with ac or when overheating. It was as simple as finding the correct wire, branching it to a switch, and then grounding the other side. Basically when the switch Is hit the ground connection is made, and even with the switch off the fan still kicks on with the ac and if it gets too hot. Of course, that setup is a pot simpler than what is found in most newer vehicles

      • 0 avatar
        golden2husky

        Usually when the condenser fans do not run, the pressure gets so high it vents the over pressurized refrigerant out….

  • avatar
    iganpo

    Neighbor across the driveway in a crowded townhouse complex has a C55 AMG that snarls like hell on start up. My baby’s room faces that way, and we leave the windows open. Maybe he used to startle when really young, but now he doesn’t pay any notice.

    (Off topic– why does an e92 m3 exhaust sound so wimpy in comparison and have a hesitant, unsmooth, idle? Seems to be missing that low v8 burble that AMGs do so well.)

  • avatar
    -Nate

    When my Son was a Teenager he got his license and bought his first car ~ a 1963 # 117 DeLuxe Sunshine Roof VW Beetle , that’s the very last year with the big old canvas sliding roof .

    It had a healthy 1200 C.C. 40 HP engine and he discovered an original 1200 ‘ extractor ‘ exhaust system in my junk pile and asked for it , it was welded up to some correct early fresh air heater boxes so I said ‘ of course *if* you can stand the noise it’s going to make ” .

    He cleaned it up and re painted it , slapped it on and roared off every morning @ 06:00 to High School , at the time I was working swing shift so I heard it light off and zoom away about three blocks worth for three years before he killed the engine racing and his next engine used a better and quieter exhaust system .

    Memories there , both of the 1960’s VW Scene and my Son as a yoot .

    -Nate

    • 0 avatar
      raresleeper

      What’s that, you say? YOOT?

      “Vinny Gambini: Yeah, two yutes.

      Judge Chamberlain Haller: What is a yute?

      Vinny Gambini: Oh, excuse me, your honor…Two youths.”

      (My Cousin Vinny)

      • 0 avatar
        -Nate

        Indeed ! .

        When I moved to Sunny Southern California I was still a Teenager and the local Girls made fun of my New England speech patterns so I had to stop and clean up pretty much my entire vocabulary .

        I miss Fred Gwynne greatly .

        Joe Pesci was the guy next door growing up .

        -Nate

  • avatar
    DeadWeight

    Popping an unstarted vehicle into neutral and rolling it backwards is fine and has no ill effects.

    Why do you have to start it before stopping it? Stop it first, then start it.

    As per your issue with construction (dis)quality, if it ain’t code, builders aren’t going to do it, period. I’ve seen residential construction quality and techniques out west (Nevada, Arizona, California) and down south (Florida, Georgia and the Carolinas) that is literally so horrific, I – and I say this without exaggeration – will be surprised if major sections of these homes are still standing in 40 years (don’t even get me started on the quality of the slurry the call cement nor the playskool style windows).

    I don’t know where you live, but as far as the bedroom above the garage, you would be wise to check with your local building department about what is code regarding insulating above your garage sheetrock/drywall and along the horizontal fascia (most likely OSB) between the studs of the wall adjacent to that room (knee wall).

    If it’s allowed where you live, insulate that wall and above your garage.

    Use self curing foam (closed cell, preferably) if you are able to (check with code) applied with a spray machine, or something like rigid foam board sealed at all joints.

    This is a very common issue. By insulating those areas, that bedroom above will be far more quiet and as a bonus, will stay far more consistent, temperature wise, with the rest of the house (it’s probably much more extreme, whether hot or cold, now).

    Here’s a good primer that covers the basics of this very common problem and the most efficient solution for it: http://www.energysmartohio.com/blog/how-to-insulate-and-ventilate-knee-wall-attics

    • 0 avatar
      DeadWeight

      I should have asked if the bedroom above the garage was a “bonus room,” with ‘clipped’ ceiling, or if it was built as an intended, insulated additional bedroom.

      If if it’s the latter (and with the caveat that I hate rooms over garages for the reasons I mentioned above) this is most likely a case of far too insufficient insulation, most likely haphazardly installed, with INSUFFICIENT AIR SEALING (the most underappreciated, hugely important factor when it comes to thermal envelope – everyone loves talking about “R” values, when a 50 R-value won’t mean squat if there are breaks in and/or improper air sealing to begin with).

      If it’s the former, look to the kneewall.

    • 0 avatar

      You certainly seem to know your stuff, DeadWeight. Thank goodness my house is just a very flat, spread-out one-story because I’m a very light sleeper.

      • 0 avatar
        DeadWeight

        Nearly everyone I known with 10′ ceilings and two story great rooms regrets those design details within a few short years due to the massive energy inefficiencies they portend (you can mitigate these things, but it costs a LOT of money to to back and try to fix a flawed design after the fact, and it still won’t be nearly as good or efficient as if a sound design was used to begin with).

        I had neighbors with $500 to close to $900 natural gas heating bills (forced air, even with zoned systems) in their 2300 to 3800 square foot homes last winter, and many of these people have new homes meeting “a more stringent, new energy code.”

        My highest gas bill with just under 2400 square feet was $187 (a month of 5 degree to negative 15 degree Fahrenheit brutal weather) with the thermostat on 70 degrees.

        • 0 avatar
          bball40dtw

          $900!

          I won’t pay $900 in natural gas bills in 2014, and my house was built in the 1940s. I also have an 80% efficient furnance (when new) that is being replaced next week. I suppose a box shaped bungalow isn’t difficult to heat.

          • 0 avatar
            DeadWeight

            There are other variables; many of the McMansions (i.e. Larger tract/production built homes with a thin veneer of fake stone grace) built recently have 30+ ginormous windows (many of which are of dubious quality, are falling apart within 5 years and were never installed or sealed correctly in the first place).

            Windows & their openings are nothing more than giant breaks in one’s thermal barrier, and glass is a horrible insulator (even if dual panes, filled with exotic gases from the periodic table).

          • 0 avatar
            bball40dtw

            I have lots and lots of brick that I tuckpoint once a year and repair/replace when needed. It is certainly better than the fake stone. I also don’t have a bunch of windows. I know the window installation on my wife’s parents McMansion was shotty at best.

            With old brick bungalows, attic insulation is important. When we bought our house, I had the attic reinsulated and installed all new windows. I did it properly and they aren’t leaking air. I have to do whatever I can to make up for the fact that there is no insulation in the walls. Plaster, lath, and brick.

          • 0 avatar
            DeadWeight

            Closed cell foam insulation on horizontal areas, as well as tacky as applied to vertical ones (it goes on sticky and self cures quickly) is the best insulation by a mile.

            You can get continuous thermal barrier coverage without interruption even over stud walls, and you’re achieving air sealing at the same time, which is the less appreciated but hugely important counterpart to the famous R-value.

          • 0 avatar
            bball40dtw

            I have the closed cell foam in my attic. I’m not peeling back the plaster to spray it in the rest of the house though.

          • 0 avatar
            DeadWeight

            Make sure your attic is very well ventilated given then large surface area of your roof that is exposed to sunlight for long periods hence the condensation monster cometh.

          • 0 avatar
            bball40dtw

            It is very well ventilated after the new roof. Since there are no soffits, we had an edge vent installed along with the ridge vent. I was worried about ice dams, but I didn’t get many last year.

            Many people make the mistake of putting cellulose insulation behind the plaster. There is no vapor barrier back there. The cellulose just gets wet. Yuck.

          • 0 avatar
            golden2husky

            …..Windows & their openings are nothing more than giant breaks in one’s thermal barrier, and glass is a horrible insulator (even if dual panes, filled with exotic gases from the periodic table)….

            Now picture a huge building that is all glass, say the new World Trade Center. A/C running in the winter for the sun side, heat on the shadowed side. A disgrace that construction methods that are so inefficient are allowed to be built. A golden opportunity out of a horrible disaster could have been taken by replacing the inefficient WTC complex with really cutting edge design. Instead we got the cheapest facade possible. What a shame. And don’t be fooled by LEED. Much of the LEED points actually eat energy in trade for excessive ventilation requirements.

  • avatar
    Sigivald

    Alternative suggestion: Park the 4Runner… outside.

    I’ve never wasted my garage space with a vehicle, myself.

    (Of course, some places it’s actually sensible or indeed the only sane option; if our author is in Arizona or Minnesota, some times of the year it’d be relative madness to deal with the environment.

    But…)

    • 0 avatar
      golden2husky

      Or one could say, “I’ve never wasted a car by leaving it outside”….

    • 0 avatar
      anti121hero

      In central new york a garage is almost needed unless you want to brush off two feet (no joke!) Of snow off your car every morning. And don’t get me started about sitting on that cold vinyl…

      • 0 avatar
        DeadWeight

        I’ve never been to a place with more frequent or deeper snow than Buffalo (I’m sure those places exist, but on a personal level, I haven’t experienced them), and Buffalo in the winter makes southeastern Michigan winter seem like a walk in the park.

    • 0 avatar
      dal20402

      I’ve never understood storing vehicles outside unless there’s no other option. It ages them horribly.

      If I have a garage space, it’s going to be used for a vehicle, to keep that vehicle in good shape. (Current place has one real garage and one covered parking spot.)

  • avatar
    superchan7

    Good thing my garage is 2 floors below the bedrooms. This isn’t an issue for any of my cars.

    For the author, I don’t see how pushing an out-of-gear car can cause any damage. You’re still on firm ground with all 4 wheels in contact. Typical suburban life of a 4Runner in the 1990s, just with the engine off.

  • avatar
    Beerboy12

    with AWD vehicles and Automatics, towing can damage the transmission. The short distance should not be a problem at all though.
    My concern would be that the brakes fail. With he engine off the brakes will fairly quickly loose pressure.
    Pressing the brakes a few time while rolling down the hill could cause this and as the brake system ages this could happen faster.
    Not being able to stop could cause a much louder bang and a very expensive one to.

    • 0 avatar
      greaseyknight

      The brakes won’t fail by doing this, the booster may use up all its vacuum and you only get manual brakes, but the driver will still have brakes. Failure of the booster is the only possibility that might cause a problem in this scenario.

      Just as long as the driver is prepared to use both feet to slam on the brakes, he should be fine.

  • avatar
    markholli

    Thank you Sajeev, and everyone else for the replies. I fully acknowledge that I appear insane for the lengths I go to in the name of infant sleep. Don’t knock it until you’ve gone months without a good night of sleep. Thankfully things have gotten better since I wrote this.

    It occurred to me while reading these comments that the location of the bedrooms over the garage and the shoddy insulation may be beneficial when they reach their rebellious teenage years and try to sneak out with the car at night. Dad will hear that door open every time.

    • 0 avatar
      05lgt

      You ever see the Sleep deprivation version of the Dexter intro? episode 401 “living the dream” has a parody intro that left me in stitches. My little one didn’t sleep through a single night until she graduated to a bed. If I’d known the stupid crib was her issue….

  • avatar
    Mike

    ….sounds like cold start knock. A oil filter with a quality silicone anti drainback valve (is this a cartridge?), and a full synthetic oil should make cold starts quieter and smoother.

  • avatar
    Yuppie

    By rolling down out onto the street before starting the engine do you have enough vacuum in the power brakes to brake hard in an emergency? This is a fairly heavy vehicle after all.

  • avatar
    jfbramfeld

    A little unsolicited advice. Do not treat an infant’s sleep as something fragile. They may wake up, but they go back to sleep if they are tired. Eventually, and very quickly, they don’t wake up no what the state of your transmission/transfer case/wheels or adult conversation. Don’t even turn the radio off. These guys are not stupid and like sleep even more than you do. They will promptly learn to sleep through the normal stuff. It is not an urban legend that some, if not most kids, sleep better in a car. On the other hand, because they are smart, they will also learn to require library-like silence if you take the trouble to train them that way. The choice is yours.

    • 0 avatar
      -Nate

      The voice of reason and experience here .

      Night lights too are unnecessary , by the time you realize you made a mistake , you’ve taught your Child to be afraid of the dark for a lifetime .

      -Nate

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