Any engine-issues that arise from lack of use?

Discussion in 'Gen 2 Prius Main Forum' started by priuslyfe, Apr 17, 2026 at 10:01 PM.

  1. priuslyfe

    priuslyfe Member

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    I have 2 prius.

    Basically, my daily driver has run well but the actuator went bad and I've put that job aside until I have more time. The hybrid-battery in this car is good.

    However, my spare Prius had battery hybrid-battery issues (bad block 3) so I installed the hybrid battery from the daily-driver into the spare.

    The spare engine doesn't sound so good as it really hasnt' been driven in 2 years. The car sputters upon letting off the gas pedal. The spare isn't insured thats why I avoided driving this car on the road.I've started it up occasionally while it sat but even that couldn't save the battery from dying.

    what is necessary to get this car that has sat running well. So far after replacing the hybrid-battery I have put in a new air-filter and was wondering if changing fluids are necessary as well. Do spark plugs go bad without use? I'm pretty sure I put new spark plugs in 2 years ago before it wasn't used at all. do fuel injectors go bad if they havent been used? I assume they have but prior to sitting, everything on this car was well-maintained.

    What is the best method to clean the fuel that has sat in the car? Should I siphon it out or drive it out. the tank is 1/4 full.

    I don't know what to tackle first or if everything needs to be fixed: dirty manifold, PCV valve, spark plugs, etc.

    Coincidentally there is quite a bit of rust of this engine now....just really not sure what to prioritize.

    [​IMG]



    ANY ADVICE APPRECIATED!
     
    #1 priuslyfe, Apr 17, 2026 at 10:01 PM
    Last edited: Apr 17, 2026 at 11:00 PM
  2. dolj

    dolj Senior Member

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    Change the oil and filter. Fill the tank with fresh gas. ¾ of a tank of fresh fuel should water down the old fuel enough. Check the tires (i. e., visually check the treads and sidewalls) and pump up to the correct pressure.
     
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  3. priuslyfe

    priuslyfe Member

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    Thanks. I figured the gas might be stale but kept just enough to start the car and let the engine run for a bit while it was left unused.

    What are your thoughts on fuel-additives? Like Techron or stuff you put in the fuel tank to clean injectors or lines? I've never used one (I've never let a car sit this long).
    My intention was always to sufficiently drive my spare Prius to avoid any issues, but since I didn't I wanna be careful about driving it now by taking every precaution.
     
  4. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    If you're going to give it any fuel additives, use a fuel stabilizer. Preferably in combination with some fresh fuel and some engine-on time to get it circulated around and through the injectors. That's generally good for 2-3 years with no ill effects.

    If you're done storing the car, just get fresh fuel in there, no need for any additive at all.

    Check all the other fluid levels and conditions, and put a careful eye on the tires. Sunlight is pretty harsh on tire rubber, dry-rot is every bit as dangerous as worn-out tread.
     
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  5. priuslyfe

    priuslyfe Member

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    Thanks.

    I was just about to buy Marvel Mystery Oil because someone at the auto-store recommended it. Seems like its less effective than Techron though per google.

    I am going to change the oil today regardless. I might siphon out the gas as well.
     
  6. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Maybe not that easy?

    And then, what to do with it? The best I've come up with, just dealing with a cup at most of brake cleaner and similar, is to pour it over a tray of kitty litter, leave it to evaporate, outside and downwind. Stir occasionally, and after about a week, bag securely and into the trash. Still, combustion is preferable I think, especially for gallon plus volumes:

    Maybe just drive it, get the remaining 1/4 tank down further, then fill up, dilute what's left.
     
  7. PriusCamper

    PriusCamper Senior Member

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    I've been delighted many times by Prius engines starting up and purring like a kitten after sitting for years... And yes, I have enough experience to know what its like when the don't.
     
  8. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Oil change isn't a terrible idea, but overall I think the best policy is to keep your wallet intact and ready for the surprises the car will throw at you. because once a Prius gets old enough, it will.
     
  9. priuslyfe

    priuslyfe Member

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    it seems to drive OK after driving roughly 5 miles. Maybe the sputter was just the initial stale-gas going through the lines.

    The daily-driver without the hybrid-battery/with actuator-issues now needs to be maintained as well now (or maybe I'll sell it)

    Entire saga of swapping the Hybrid battery and now maintenance really makes me wonder how people with a lot of cars maintain them tbh. Sure Jay Leno can hire people to have a spreadsheet of his cars, but how do others with many cars do it?
     
  10. priuslyfe

    priuslyfe Member

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    tell me about it!

    the other prius is on its last legs PRIOR to the actuator issue. It has maybe 350K miles but other mechanical parts that I can see are pretty worn. Which I attribute more to Ohio weather than my driving. Not sure if I should get rid of it or fix it and keep it as my spare. The actuator job might be OK though. Any car-repair that doesn't affect your ability to get around because you have another car is kinda fun. still not looking forward to it.
     
  11. pasadena_commut

    pasadena_commut Senior Member

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    Water (drops) on the bottom of the tank?