By on October 24, 2011


Jonathon writes:

I’ve been remiss about getting results back to readers.  I took the car to the Honda dealer who pushed hard for the power flush . . . only to have the technician do the 3X manual flush.  Turns out that only some 2003 V6 Accords have the available connections to handle power flushing.

Results?  The transmission has been Smoooooooooth ever since — how could it NOT be when the old fluid looked and smelled like old, overcooked coffee? Because the final draining still smelled a little off, I’ll probably do yet another tranny drain with the next oil change.

 Thanks for the advice.

Sajeev Answers:

Who-hoo! I take any victory I can get in the Piston Slap business.  Excuse me while I shamelessly pat myself on the back. Par-taaaay time, son!!!

Okay, serious time.  This letter is proof that regular fluid changes ensure a healthy and happy transmission or transaxle.  Combined with common sense actions (like coming to a stop between reverse and drive engagement) and a large aftermarket transmission cooler for those who must endure hot summers in urban traffic. Or for anyone who loads up their whips more than with just yourself, your iPod and a latte.

Best and Brightest, will you accept a challenge to do just this for your personal slushbox?

Send your queries to sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.

Get the latest TTAC e-Newsletter!

47 Comments on “Piston Slap: Honda Slushbox Fail…Averted!...”


  • avatar
    Boff

    I wish I could help, but I don’t know how to drive an automatic…

  • avatar
    tankinbeans

    I’ve haven’t been to Kwik Trip for a slushy in awhile. Are there any good ones now?

  • avatar
    Caraholica

    One of the glorious features of Honda’s is the drainplug on the bottom of the automatic transmissions. It is distinguished from the engine oil drainplug by having a socket head fitting rather than a bolt. If the dealer really did this 3X as Honda recommends you have about 87% or better new fluid. New fluid is good.

    This makes it very easy to drain the auto trans and refill at home just as you would the engine, if you are so inclined. Go ahead and do this if you have the urge. There are many approaches, I change mine with the 3X method about every 30k miles, some have a semi-hidden inner filter, like my ’06 Odyssey, some dont seem to. My experience is that Honda ATF works better in these.

    BTW, does anyone know what trans design allows this while most of the rest of the world has drain pans that require a lift and fiddly gaskets?

    • 0 avatar
      Ion

      It’s not really a special design just whose engineers and bean counters took the time to consider that joe schmo might want to do a quick drain and fill in his driveway. I’ve seen em on a few cars now and then, an off beat example would be a PT Cruiser. There’s even a few aftermarket kits to put a drain plug on a pan that doesn’t have them.

      Now sealed transmissions where the drain plug IS the fill plug are a different story.

    • 0 avatar
      anonymic

      The other thing that distinguishes the trans drain plug from the engine drain plug would be that the trans drain plug is on the transmission.

    • 0 avatar
      deanjet

      Cool beans, my wife also has a 2006 Honda Odyssey. I pull the transmission plug every oil change. The way I figure it, I replace about 1/3 of the tranny fluid every oil change. It’s not very difficult to do and it’s good for the car in the long run.

  • avatar
    Pinzgauer

    Did they switch you over to ATF-DW1 when they did the change? Honda discontinued the old ATF-Z1 earlier this year so I presume they did. Some theorize that this fluid has been the cause of many Honda transmission problems. The Z1 really did not seem to last well, and shift quality would slowly degrade over time. DW1 is supposed to be a full synthetic, and Z1 was not.

    I myself do the 4qt drain/fill on my 08 Pilot every 12k. Just put my first 4 Qts of DW1 in last week and I think it shifts better. Also added a tru-cool transmission cooler and magnefine filter. I hope this makes it last.

    • 0 avatar
      tonycd

      Not so fast. As an Acura owner, I’ve been reading up on this issue. BobIsTheOilGuy and rl.acurazine.com have good info on this.

      Some believe that Honda replaced Z1 with DW1 not because the latter is better for the transmission, but because of production restrictions and environmental issues.

      Two telltale indictments of the new DW1 fluid:
      1) Z1 was recommended for AWD rear differentials as well as transmissions. DW1 is not.

      2) Honda is actually advising that if owners are unhappy with the rough shifts they get with DW1, the fix is to drain a quart of it and substitute a quart of Z1 (if you can get it; it’s discontinued and disappearing fast).

      I also don’t believe DW1 is a full synthetic; I think it’s a blend. There are two quality substitutes that are definitely full synthetic: Amsoil Universal ATF, and Valvoline MaxLife Dexron/Mercon. After reading everything I could find on the subject, I used the latter, mostly because of availability.

      Finally, a note on tranny flushing: I don’t recommend it, and Honda doesn’t either. They recommend the three-drains approach. I’m appalled that a Honda dealer was pushing for a flush job. If the previous motorist had metal bits in his fluid, and the dealership did anything less than a 100% immaculate job of cleaning out the flushing equipment before doing yours, a perfectly good tranny can be turned into a boat anchor in weeks.

      • 0 avatar
        Pinzgauer

        I read the same forums and have heard both ways about shift quality and DW1. In my case quality definetely smoothed out, but it could just be old fluid vs new fluid. As for the AWD argument, atleast in the pilot the rear “diff” takes VTM-4 fluid made specifically for the applicaton. Real nasty smelling stuff I must say. There is alot of debate about Honda ATF because there is not much information out there about it from Honda.

      • 0 avatar
        MBella

        On a Trans Flush machine the old fluid goes into one tank while the new fluid goes into another. There is no cross contamination. They usually hook up inline with a trans cooler line, and let the trans pump push fluid into the machine while new fluid goes back into the car. It is a concept similar to how a turbocharger works. The trans pump sends fluid into the machine past an impeller that drives the pump to push fluid back out.

    • 0 avatar
      tonycd

      Not so fast. As an Acura owner, I’ve been reading up on this issue. Some believe that Honda replaced Z1 with DW1 not because the latter is better for the transmission, but because of production restrictions and environmental issues.

      Two telltale indictments of the new DW1 fluid:
      1) Z1 was recommended for AWD rear differentials as well as transmissions. DW1 is not.

      2) Honda is actually advising that if owners are unhappy with the rough shifts they get with DW1, the fix is to drain a quart of it and substitute a quart of Z1 (if you can get it; it’s discontinued and disappearing fast).

      I also don’t believe DW1 is a full synthetic; I think it’s a blend. There are two quality substitutes that are definitely full synthetic: Amsoil Universal ATF, and Valvoline MaxLife Dexron/Mercon. After reading everything I could find on the subject, I used the latter, mostly because of availability.

      Finally, a note on tranny flushing: I don’t recommend it, and Honda doesn’t either. They recommend the three-drains approach. I’m appalled that a Honda dealer was pushing for a flush job. If the previous motorist had metal bits in his fluid, and the dealership did anything less than a 100% immaculate job of cleaning out the flushing equipment before doing yours, a perfectly good tranny can be turned into a boat anchor in weeks.

  • avatar

    PISTON SLAP WIN!

    will remember your words of wisdom if I ever get a slushie.

  • avatar
    johnhowington

    i recently picked up a 98 accord 4 cylinder auto with 166k having a shudder going into 4th/overdrive. two flushes with vavoline maxlife (the best alternative to honda ATF) and it has been excellent for 1000 miles so far.

  • avatar
    redmondjp

    Transmission doctor: “You’re in remission, but the cancer is still there. This treatment has just bought you some time; how much, nobody can really say. And when it does come back, it can happen fairly quickly and without warning so don’t plan on taking any extended vacations out of state.”

    This is the same problematic transmission as used in the 2002-2004 Odysseys, go to http://www.odyclub.com/forums/ and you can read about transmission problems for the next month. The root cause is an underdesigned clutch pack that slips, overheats, and eventually disintegrates, contaminating the hydraulic system with bits of clutch material. Replacing the burnt fluid has solved the effect, but not the root cause.

  • avatar
    Truckducken

    FYI: Toyota Siennas (at least the gen including the 2008′s) also drain with a plug. I drain a gallon every summer and refill with +4 (no, not the Mopar stuff). Takes a good ten minutes – highly recommended. I suppose once every few years I oughta do the 3x job, but since the fluid still looks and smells good, I’m not rushing into it.

  • avatar

    I don’t have a slushbox.

    How often do you recommend to flush the slush?

  • avatar
    acuraandy

    I drain and fill both my 97 Accord and my brother’s 04 Civic slushboxes every third oil change, with positive results. Especially with the new ATF DW-1 that Honda came out with about a yr ago. Apparently it promotes smooth cold-temp shifts, which is an advantage here in Siberiasota.

    Think of it as ‘cheap insurance’.

    With that said, the 98-03 Accord/TL V6 slushboxes are complete rubbish. On the Acura side they had a recall for an oil jet kit installed into the fill plug that would spray ATF onto second and third gear while shifting to attempt to cool down said gears. It seemed to work. Especially while ignoring the 120k recommended fluid change and doing it at LEAST every 30k.

    • 0 avatar
      acuraandy

      And P.S., under no circumstances or model years do we recommend power flushing on ANY Honda/Acura automatic transaxle; with the exception of a transmission replacement to flush out the lines.

  • avatar
    Ubermensch

    Do auto shops even use “power flushers” anymore? The Subaru shop that “flushed” my Subies transmission used a BG fluid exchange machine that has 2 bladders, one for the old fluid and one for new. There is no possibility of contaminating the new fluid with old and the machine uses the transmissions own pump to move the fluid. There is no “power flushing” going on. This method also has the benefit of getting out almost 100% of the old fluid.

  • avatar
    Educator(of teachers)Dan

    Will this method of poor the fresh stuff in until the fluid starts to run clean work with a trans with no drain plug for the torque coverter?

  • avatar
    obbop

    Any votes for Slick-50?

  • avatar
    Wheeljack

    Now that you’ve restored the shifting and have clean fluid, add an auxiliary transmission cooler to help prevent failures in the future.

  • avatar
    drno

    I got a new transmission in our 2001 Odyssey @ 90,000 miles (under “warranty”) some 4 years ago. Does the replacement tranny solve these issues? We now have another 40,000 miles on the vehicle…no fluid change performed.

  • avatar
    turbobrick

    Don’t people change their ATF anymore? I flush out 8 – 10 quarts of old stuff out of my ancient AW71′s every 25 – 35 thousand miles. Those came with metal screens instead of paper filters and there was a TSB that said don’t even bother opening up the pan.

    I just hook up a piece of vinyl tubing in the output side of the oil cooler, start the car, let it pump out 2 quarts, stop it, refill it, and repeat. No fancy cocktail fluids here, just regular Pennzoil Dex-III from the yellow bottle, or whatever they call it now.

  • avatar
    jpcavanaugh

    Fluid changes in my 07 Honda Fit every 30K miles. Just had the second one done.

  • avatar

    The ATF+4 in the 47RE in my Ram 3500 gets changed once a year, regardless of mileage. Of course, my truck gets driven hard and can be found pulling a large 5th wheel camper or car trailer several thousand miles a year, too, unlike most trucks. And, of course, I’ve got a high-end aftermarket converter (FTI, FYI,) a valve body shift kit and a tuner to tweak the shift behavior, because all of that is mandatory in a non-Allison diesel truck.

  • avatar
    Windy

    Between 1967 and 1997 I put 750,000+ miles on a M-Benz 250 SE that we bought via euro delivery and picked up in Stuttgart and put the first 7000 miles on driving about Europe and the UK that summer; brought the car back as hold baggage on the old Queen Elizabeth (Wish I had a photo of the car being swayed up out of the ships garage with a dock side crane)

    As far as I can recall we never did anything to the transmission though it got a short block rebuild at the dealer at about 400,000 and the limited slip differential started to whine at about 550,000 but it never failed till the Tin worm killed the car (still I sold the remains for $1000 to a chap restoring a convertible (he really liked the green leather seats)as the car was loaded with every option that M-Benz offered at the time other than Air conditioning (even had the euro one piece forged trailer hitch and dual city/country horns and euro radio with the long wave and short wave bands in addition to AM/FM) I suppose they might have flushed the Trans. when it was getting its short block but I do not recall it…..

  • avatar
    ponchoman49

    This is why I’m glad for the good old fashioned drain pan and that thing they call a removable filter in my Impala. Sure it can be a little messy but your clearing out all the fluid in the pan, changing the filter and cleaning out the magnet and the pan. Power flushing would only move the debris back into the tranny and filter causing other potential problems in this setup. I drop the pan every 50K or so and have been doing this for the last 25 some odd years and have never lost a transmission yet.

  • avatar
    cstoc

    I must second the advice for regular ATF changes. I always changed it in my cars every 30k miles no matter what the manual said and have never had tranny problems. I can also recommend Sea Foam Trans Tune. Put a little in before changing the oil, it gets some extra gunk out. My 8-year old Chevy Avalanche’s transmission is noticeably smoother shifting since the last treatment and oil/filter change.

  • avatar
    bobby b

    Speaking as someone who just paid $3400 to get an MDX tranny rebuilt, let me throw in my two cents here. (I might as well – it’s all I have left, and you can’t buy anything for two cents.)

    This tranny is famous for this. 2nd-3rd clutchpack fries. Starts as a touchy shift, progresses to a slip and a hard catch. If you notice it just as the 2nd-3rd shift starts to feel rough and do a complete fluid change, you MIGHT get some extra miles out of it. If you’re slipping, it’s too late – no matter what you do, the slipping is just going to get worse until you coast to a stop.

    (What idiot designs a transmission drain plug that can only drain three quarts from a ten-quart reservoir? “Here, let’s put it in this smaller, higher compartment! It won’t work, but it’ll fit so much nicer!”)

  • avatar
    sastexan

    The Honda dealer thought I was crazy (and told me so) for getting JUST the ATF cooler from the towing package for our new Odyssey. No hitch and harness – don’t need it. But I don’t trust the tranny especially with it being used in the equivalent of taxi service (adding in lots of cold starts and not much warm up, then random times with lots of idling). Torture for the mechanicals.

  • avatar
    Moparman426W

    Jonathon, the reason the fluid looked and smelled like burned coffee is because the trans is shot. What you saw and smelled in the fluid was burned up clutch material. The new fluid is a short term fix, the tranny will die soon.

  • avatar
    CougarXR7

    @ Acuraandy- I used to do those transmission campaigns on V6 Accords all the time when I used to work at Scott Robinson. They seemed to work. As part of the recall, we used to take pics of the clutch drum using a digital camera mounted to a special pedestal, and send the pictures to Honda North America. If the clutch assembly was normal color it was considered OK. If it was blued from heat, it was toast.

    My ’95 Lexus LS400 has a trans drain plug. I bought it last year with 80,000 miles and it now has 101,000. I really need to service it. The fluid is just starting to become brown and developing a funky smell.

    The one thing I don’t like about those machine flushes is the fact that they do nothing about the dirty filter or the gunk trapped at the bottom of the pan.

    I’m thinking of switching to Mobil synthetic ATF.

  • avatar
    blowfish

    When i had my old Volvo, i read about changing ATF is by un-doing one of the trans cooler line to the bottom of the rad. Put her into an empty can, start the car running at idle the old ATF will slowly come out, u keep adding new ATF into the filler/ dip stick tube.
    just put 4-5 litre in it. One of my old Volvo the stuff came out, looks like semi-solid / jello substances came out. The car ran much smoother afterward. Since then I haven’t bother to do anything in my Mercs.

  • avatar
    joeaverage

    Drain the pan and then remove the pan and wipe it out. New gasket. Can’t tell you how many autos I have drained and then removed to pan to find a sludge int here that didn’t get washed out.

    I have zero interest in owning an auto transmission. It’s a $1500 option with a $2500 guaranteed rebuild if you own it long enough. Give me a 5MT or a 6MT any day. I can R&R the clutch for less than $500 myself.


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