Piston Slap: Sleepless Above The 4Runner?

Sajeev Mehta
by Sajeev Mehta
piston slap sleepless above the 4runner

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 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 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.

Join the conversation
3 of 65 comments
  • Yuppie Yuppie on Sep 23, 2014

    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.

  • Jfbramfeld Jfbramfeld on Sep 23, 2014

    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.

    • -Nate -Nate on Sep 23, 2014

      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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