Electric Water Pump replacement and loss of fuel economy

Discussion in 'Gen 2 Prius Main Forum' started by bigfatdad, Feb 4, 2011.

  1. bigfatdad

    bigfatdad New Member

    Joined:
    Feb 4, 2011
    5
    0
    0
    Location:
    CT
    Vehicle:
    2005 Prius
    Model:
    N/A
    After my electric water pump was replaced under the recall my mileage went from 45 mpg to about 30 mpg. Part of this might be due to new tires and cold snowy weather (CT !) but I have never seen such a drastic drop in performance (2005 Prius). Has anybody else had this experience?
     
  2. firepa63

    firepa63 Former Prius Owner

    Joined:
    Jul 23, 2005
    1,761
    201
    0
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I doubt that the water pump has anything to do with the drop in MPG, but the cold weather sure does. New tires will also contribute to the loss. I'm also running in the 30s, but I have a lot of short trips that I make. I wouldn't worry about the drop. Take about an hour's drive and I think you'll see the mpg back up close to 50.
     
    1 person likes this.
  3. Politburo

    Politburo Active Member

    Joined:
    Feb 15, 2009
    971
    207
    0
    Vehicle:
    2009 Prius
    Check the pressure on the new tires, as well.
     
    1 person likes this.
  4. ystasino

    ystasino Active Member

    Joined:
    Apr 17, 2007
    792
    47
    0
    Location:
    Tucson, Arizona
    Vehicle:
    2007 Prius
    Model:
    Two
    The only way I can think of that any Prius would normally run at 30 mpg even in CT is on widely separated 5 minute trips with a lead foot with the engine staying stone cold.

    We had temps in the low 20s for all of Jan and I was never below 40 mpg. However, the OP hasn't said anything about changing his driving habits since the 45 to 30 mpg drop. Or is 45 mpg a "summer-time" figure?

    Did the dealer do anything else to your car, like overfill the oil? My dealer took a piece of chalk and wrote "4 qrts-synthetic" in the engine compartment just so that nobody overfills it ever. Tire pressure is important (I run front and rear at 44 psi and 42,000 miles later they still have tread) and dealers will remove extra air every time you take your car to them.

    Slowing down your acceleration is something that could help.
     
  5. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,723
    2,115
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    New tires take about 1500 miles to bed in nicely. Also the type of compound and/or type of tire makes a big difference. If you previously had low rolling resistance and changed to a cheapo tire then you will get a drop in mpg's.

    Check the pressures and see how it goes over the next 1500 miles.
     
    1 person likes this.
  6. bigfatdad

    bigfatdad New Member

    Joined:
    Feb 4, 2011
    5
    0
    0
    Location:
    CT
    Vehicle:
    2005 Prius
    Model:
    N/A
    I noticed the tire pressure was down to about 29 psi on all four tires so I cranked it up to 36 and took a few longer trips yesterday with the temps in the 30's and got the mileage up to 40. Still not near my overall average of 45 (~47 summer, ~43 winter for the last 5 years!), but that could be the combination of the new tires and the cold snowy weather. I'll go for another few fill ups before I take any action.

    I was suspicious of the the dealer since they recommended the main water pump replacement for $600 and the usual engine and cabin air filter replacements for the usual outrageous dealer prices.
     
  7. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,539
    2,105
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    36 psi is not my idea of cranking it up. I'd go higher.

    As for new tires, what did you get? They could have higher rolling resistance than your previous tires. Even if you replaced them w/identical make, model and size, a hit is likely. See Tire Tech Information - Tire Rolling Resistance Part 3: Changes to Expect When Switching from Worn-Out to New Tires.

    Yes, cold weather, esp. in snow will affect your mileage.
     
  8. bigfatdad

    bigfatdad New Member

    Joined:
    Feb 4, 2011
    5
    0
    0
    Location:
    CT
    Vehicle:
    2005 Prius
    Model:
    N/A
    Reply:
    I have Goodyear Assurance tires. Probably not the best for mileage but I got a very good deal ($70 each). I'll crank up the pressure to 38 or 40 when the snow melts (if ever!). Do you think I should go higher?
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,130
    6,153
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    I would suggest 44/42 psi; check the max cold inflation pressure spec on the tire's sidewall to ensure it is at least 44 psi.

    Regarding the engine coolant pump, I recommend that you look at it to satisfy yourself that the bearing isn't leaking coolant.
     
  10. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,215
    1,179
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Goodyear Assurance what tires?

    There are several different Goodyear Assurance ties and they're not all the same as far as rolling resistance is concerned.

    Goodyear Assurance Fuel Max = Low Rolling resistance.

    Goodyear Assurance TripleTred or ComforTred = not so good.

    What type do you have?
     
  11. bigfatdad

    bigfatdad New Member

    Joined:
    Feb 4, 2011
    5
    0
    0
    Location:
    CT
    Vehicle:
    2005 Prius
    Model:
    N/A
    Last two sets of tires were both Comfort Tread. I think the design has changed since the lst set but they were great in the snow this path month. And we had plenty of snow this year in CT. A record for the month of January. 80" so far this season (average = ~ 27")
     
  12. seilerts

    seilerts Battery Curmudgeon

    Joined:
    Mar 7, 2010
    3,326
    1,481
    38
    Location:
    Santa Fe, NM
    Vehicle:
    2005 Prius
    Don't play poker with that service advisor. I don't know how they could give you an estimate that high and keep a straight face. $350 seems to be the average.
     
  13. striker308

    striker308 Three time Prius owner

    Joined:
    May 11, 2008
    302
    43
    0
    Location:
    Evans, NY (USA) / South Williamsport, PA (USA)
    Vehicle:
    2014 Prius
    Model:
    Three
    Mine runs in the 30's all winter, soon as spring hits I'm back up to the 40's. I only hit the 50's on back roads/small town driving. I haven't had mine replaced yet but with 110K on it I'm thinking its time now that its free. The dealer told me 30K ago that the water pump (gas side) was leaking and needed replaced I told I'd do it. I refilled the reserve tank after cleaning up the "leak" and haven't seen any leak since. I guess I should replace that sometime soon with all the miles on it.
     
Loading...