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Kia Optima Hybrid - how does it work?

Discussion in 'Other Cars' started by adric22, Apr 16, 2012.

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  1. adric22

    adric22 Ev and Hybrid Enthusiast

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    I've been trying to scour through google and find some information on how the drivetrain in the Kia Optima Hybrid works. But I'm not having much luck.

    I know that it is different from the Prius since it has an actual 6-speed transmission. Yet, It appears to be significantly different from the Honda IMA setup too, since it can drive on pure electric with the engine shut off.

    Can somebody explain how it works? Or point me to an article or other website?
  2. seftonm

    seftonm Member

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  3. adric22

    adric22 Ev and Hybrid Enthusiast

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    Fascinating. I read through the article. I have to wonder if that system will be as reliable as the Toyota HSD over time. Specifically, will those clutches wear out? Or does the computer time everything perfectly so that there is very little friction on the clutch discs?
  4. justlurkin

    justlurkin Señor Member

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    The Hyundai "clutch-IMA" system will never be as reliable as HSD.

    For mechanical reliability, simpler is better. With 100+ moving parts in the 6-speed transmission, torque converter, and clutch for the ICE and electric motor, there are a lot of potential mechanical failure points.

    Prius HSD has all of 27 moving parts. Less potential mechanical failure points, and no clutch wear.
  5. Trollbait

    Trollbait It's a D&D thing

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    While true, it does have an efficiency cost. Especially in the PHV where a clutch to decouple the ICE could mean increased EV range. Simplicity generally lacks flexibility.

    And how reliable do we need the drivetrain to be? With regular maintenance, a transmission should last the service life of the car. Maintenance that the Prius transmission also requires. All those parts do increase the cost in materials and quality assurance time, but the HSD doesn't eliminate those costs when it needs motors and a traction battery.

    Doesn't the motor on the Kia hybrid replace the torque converter?
  6. justlurkin

    justlurkin Señor Member

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    What maintenence does the Prius PSD require? In the maintenance schedule booklet, Toyota says none, except to inspect the fluid levels every 30,000 miles. We at PriusChat recommend a WS fluid drain-and-refill every 60,000 miles.

    As far as the reliability of a regular-car automatic transmission goes, those tend to work at a pretty hot temperature. I remember in my old Jeep Cherokee the operating temperature of the ATF fluid was 230F. That kind of running temperature does tend to be hard on things like the seals. It was leaking fluid at 80,000 miles, and if that's the "lifetime" of the car, it's rather short. And, I had to replace the ATF every 20,000 miles on that car's automatic transmission.

    The Prius PSD's fluid doesn't get anywhere near that hot, so the seals would last far longer. I doubt I will ever see my Prius leak transmission fluid unless I do something stupid like crash the car. As far as I know, the electric motors in the Prius PSD are not items one would routinely service in maintaining the car.
  7. Trollbait

    Trollbait It's a D&D thing

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    Toyota guides never say anything about changing the coolant, but just to inspect it, too.

    Inspecting coolant is simple and easy. The overflow tank is right there, and coolant testers are inexpensive. Not so with the PSD fluid. To get to either plug requires jacking up the car, crawling under it, or removing a wheel. Like motor oil, just looking at the fluid is a poor judge of its condition. So inspecting likely entails having it tested. For the time and expense involved with the inspection, just changing it is probably a more economical solution.

    Several gen2 owners changed their fluid at 30k miles, and reported that the fluid smelt burnt. It very well may have been fine. Whether an owner follows Toyota's 30k mile code for 'support your dealer' or follows Priuschat's more reasonable 60k mile fluid change, that still within the service interval range of most automatic transmissions. The manual for the HHR says 50k with severe duty. Supposedly it's maintenance free otherwise. I changed mine at 100k. The parents' Acura has a sealed transmission, and I don't think they are concerned with it lasting to 200k miles.

    200k miles is over 10 years for most drivers. If a car doesn't require a major repair, or regular little ones, then most people would feel it was a reliable ride.



    What was the engine temperature? 230F is high for normal ATF operating temperature. It should be in the 170F to 190F range. If the coolant temp wasn't as high, you probably had a blockage or restriction in the transmission cooler. The older transmission fluids could start degrading at temperatures in the 200F to 225F range. It can get higher while towing, but then all the fluids should have a shorter service interval.

    Maybe it is just because it was a Jeep :), but I wouldn't use it as an example of what to expect out of a modern automatic in life term. Would you doubt a Toyota automatic could last the life of the car?
  8. austingreen

    austingreen Senior Member

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    Modern automatic transmissions are extremely reliable. Hyundai says that the electonics match speed very well so there should be little wear and tear on the clutch.

    That said the HSH is in its first generation, which means there are some rough edges to the design. The new TCH or upcoming 2013 FFH might be safer bets.:D These are both second generation hybrids with the TCH getting combined 40 or 41 mpg and the FFH 45 mpg compared to the hyundai's 37.
  9. finman

    finman Active Member

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    my 2004 manual says change coolant 100,000 miles, then again after every 50,000. I've changed my PSD oil twice on my 2004 and twice on my wife's 2005, once each on a family member's 2007 and 2009. Never had to pull a wheel to do the deed.
  10. Trollbait

    Trollbait It's a D&D thing

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    I somehow had the impression that the fill port for the PSD was behind the wheel well. Oh, well. Is it possible to pull fluid from the fill port for inspection?

    I remember inspect being a common term in my 2005 service schedule. Reading the the footnote left me with the impression of, 'take it to the dealer so he can charge you to change it." But that was awhile ago. Looking up schedules online has me believing Toyota, and most manufacturers, just have a generic schedule they use for all cars. The Prius one has instructions in case of towing, and the Camry also only has an inspect for the automatic transmission fluid.
  11. finman

    finman Active Member

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    sure. unscrew the fill bolt, and a bit o' fluid will normally seep out. collect it in a pan . inspect away. not easy to see that fill port, but still doable from under the car with the top front plastic cowling removed and plenty of light shining down. there's a great pic floating around Priuschat that shows this that i printed out long ago.
  12. Skoorbmax

    Skoorbmax Senior Member

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    It's unlikely that this tranny will be as reliable as Toyota's HSD because a) It's not an HSD and b) it's Kia (or Hyundai or whatever source they got it from).
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