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Low Transmission Fluid

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Emily_0021, Dec 15, 2014.

  1. Emily_0021

    Emily_0021 Junior Member

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    Hello. My transmission fluid had never been changed (to my knowledge) in my 2004 (155k miles) prius and after some research I decided the best course of action was to change out a quart or so at a time to let the transmission adjust to the new fluid. Perhaps that is stupid or wasteful to those who are more knowledgeable but better safe than sorry. Anyway, Toyota would not drain and replace a single quart but Cottman Transmission said they would. However, I watched and I know for a fact that they took more than a quart out, but I only had 1 quart of ATF WS for them to refill with, so my transmission fluid is definitely low. I would estimate that it is low by 1/4 - 1/2 quart. (Cottman said the fluid didn't look too bad for the miles on the car, but it was brown, not translucent pink like the new fluid.)

    My question is: Will driving for a week (~150 miles) with 1/2 quart of transmission fluid missing cause damage to my car?

    Toyota wont "top off" the fluid and says that they must do a complete drain and refill service ($190) so I am going to purchase and borrow the equipment needed for me to add fluid myself. (ramps, fluid pump, torque wrench). And then I can drain and refill a quart or 2 myself in a couple months to continue slowly replacing the old fluid.

    Another question: I have wrenches but not a wrench that I can set to the specified 29 ft-lb. Will I damage my car if I don't put the plug back in at 29 ft-lbs and just screw it in until it is tight?

    Also, Toyota claims that the transmission fluid must be drained and filled using a computer to do it properly but I see tons of DIY instructions and it looks super easy. Can DIY without the computer cause damage to the car? Has anyone regretted doing it themselves?

    Thanks!
     
    Troy DIY likes this.
  2. JC91006

    JC91006 Senior Member

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    I would bring it back to Cottman and give them 4 quarts of ws fluid and have them drain the entire thing at once. There is no advantage in doing it a quart at a time. The old fluid mixes with the new fluid and your end result will be slightly cleaner fluid.
     
  3. valde3

    valde3 Senior Member

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    Prius transaxle isn’t traditional automatic transmission. There aren’t hydraulic parts inside. No point in changing it one quart at the time. Just change all fluid at the same time. No need to use computer to change fluid.
     
  4. Emily_0021

    Emily_0021 Junior Member

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    Thanks. But can anyone tell me if my car will be damaged if I drive for a week on low transmission fluid? I can't top it off today and even if I go back to the dealer and have it completely drained and changed, I have to drive the car with low fluid.
     
  5. JC91006

    JC91006 Senior Member

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    It's best you go and change it out asap, but if your guesstimate is correct about 1/2 quart low, it won't be the end of the world.
     
  6. bisco

    bisco cookie crumbler

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    i wouldn't risk it. the oil is supposed to be up to the bottom of the fill hole. don't know if it will cause damage, but better safe than sorry.
     
  7. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    Driving for a week will not be a big deal as long as its only a 1/4 or 1/2 quart low.
     
  8. frodoz737

    frodoz737 Top Wrench

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    Go back and get it all changed asap. If you knew "for a fact" exactly how low you were, the sense of urgency might change, but at 155K you are past needing to change the ATF anyway. Your questimation about the level is just that, so don't chance it. That is an expensive tranny.
     
    uart likes this.
  9. Yakoma

    Yakoma Active Member

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    ^^ What he said.
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Since you want to be safe and not sorry, there is nothing safe about driving the car while knowing the transaxle ATF is low. You are risking damage to a part that will easily cost four-figures to replace even if you install a used transaxle.

    There is absolutely no need for Toyota Techstream. The job is a simple drain and replace. Also you are wasting time and effort by not replacing all four quarts of ATF-WS at once.

    Since you do not want to be sorry, you will regret DIY if you don't have the correct tools and do not utilize a safe repair method. Get a decent 1/2" clicking torque wrench and the necessary sockets: a 24 mm (or 15/16") six-point socket and 10 mm hex key socket. Don't buy the cheapest tools you can find at Harbor Freight.

    The 10 mm socket probably will come in a 3/8" size so you'll need a 1/2" to 3/8" adapter. Make sure you can raise up the car safely on jack stands. If the car is too low it will be hard for you to find the transaxle fill plug and exert the necessary force on the torque wrench.

    Another reason why you might be sorry about DIY is if you open the drain plug and let the old ATF drain out; then find that for whatever reason you cannot open the fill plug. So always make sure you remove the fill plug before you remove the drain plug.

    The point of using a torque wrench is that your idea of "tight" may not be the same as mine. That is the reason for a torque spec. If you really can't afford a torque wrench then strive to tighten the fitting using the same force you had to exert to remove the fitting.
     
    #10 Patrick Wong, Dec 15, 2014
    Last edited: Dec 15, 2014
    uart and Epiphany2000 like this.
  11. Mike500

    Mike500 Senior Member

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  12. Mike500

    Mike500 Senior Member

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    Harbor Freight makes a decent $10 (with coupon) torque wrench.

    Check this out;

    Torque Wrench Testing - Shop Tools - Car Craft Magazine

    Just remember to return it to the lowest setting after use.

    I own Snap On's and about twelve others. The 3/8 inch Harbor Freight is a good deal.
     
  13. Yakoma

    Yakoma Active Member

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    +1...HF 3/8 is the one I have and it works well.
     
  14. Emily_0021

    Emily_0021 Junior Member

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    So I was about to buy a set of ramps, a jack and jack stands and a torque wrench to top off the fluid for myself ($120+) then decided I should just try to have someone else do it again. I took it to Meineke ($20) and gave them the quart of ATF WS fluid, a fluid pump and a crush washer and asked them to add fluid until it was full. They had to add almost an entire quart!!! I think I only drove about 1o miles with the low fluid but wow that's bad, huh? The Meineke guy said there could be damage to the transmission but that he didn't know what to tell me to look for since it's a hybrid. What are the signs of a bad/damaged transmission?

    I noticed (on the 7 mile drive home) that my car's gas engine turned on less and that I didn't feel the car changing gears as I sped up. Usually I speed up and then take my foot off the gas a little and it shifts gears and the mpg increases but the speed of the car does not decrease. Today when I did that I didn't feel a gear change and the mpg never jumped up like it used to. These changes seem good though, not bad. I think it is changing gears more seamlessly. What do you think?
     
  15. JC91006

    JC91006 Senior Member

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    What's done is done and there's no looking back. Hopefully you'll be fine, if not, the car will let you know by throwing a DTC code. You shouldn't feel any gears shifting in the cvt transmission. It's only 1 gear.
     
  16. xliderider

    xliderider Senior Member

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    Why did you only get 1 quart again? You still have 2 dirty/old quarts of fluid in the transaxle.

    Since you went through the trouble of taking it to someone, why not buy 4 quarts of WS and 2 crush washers, then have them drain the transaxle completely and refill with new/fresh fluid? SMH
     
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  17. Yakoma

    Yakoma Active Member

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    What he said. :confused:
     
  18. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    You've bought yourself some time. My 2 cents: sometime soon, get it completely changed. Sounds like you're game to DIY. It's not that hard. There is NO need for computer interface, it's purely mechanical job. Do keep in mind the car should be level when adding fluid, to get the level right. Just pour in till it starts coming back out. A pump will work, but is kinda overkill. Just a funnel with a longish hose (around 3 foot) will work. Snake it down through the engine compartment. A helper to pour while you watch for it to start overflowing is a good idea. Get the info on the 2nd gen fill and drain bolt types, in advance.

    I've done DIY change of ours twice now, and we're only around 49000 kms.
     
  19. dolj

    dolj Senior Member

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    Hi Emily,

    As JC has said, there are no gear changes due to the design of the "power split device". However what you observed is a thing and I do this all the time too. I find that after my initial acceleration, which is brisk 10-13 MPG (US) (18-23 l/100 km), I can back off the accelerator and maintain the same rate of acceleration but decrease my instantaneous fuel consumption (->20-26 (US) 9-12 l/100 km). This is one of my secrets (now not so secret) to better MPG's. The phenomenon is do with the computers re-jiging the combination of ICE and electric motor contribution to the total power output and not gear changes like in a manual or conventional auto.

    I don't know what to tell you about what you have observed, but I don't think it is cause to worry. Keep an eye on it it, hopefully it is just a temporary aberration and normal transmission (pun intended) will resume in due course.
     
  20. frodoz737

    frodoz737 Top Wrench

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    Have the Transmission fluid changed. Rack up the extra money already spent to experience.