Engine knocking/shaking at 236k. Worth trying to fix?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by gradyoactive, Sep 3, 2021.

  1. gradyoactive

    gradyoactive Junior Member

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    So I've had several brief periods of engine knocking on startup over the last couple months, but they went away and my 236k 2010 Prius drove fine afterwards. But a couple days ago, I was idling a lot waiting for my girlfriend to finish errands, and after another 30 minute idling session, my engine started knocking and shaking hard. I shut it down, and then made it home OK. But the next day it was knocking a lot while driving, so I cancelled my drive and lurched home. I noticed that the coolant was a little low (not super low), so I refilled it. And I added oil. The next day I tried starting it and it knocked uncontrollably.

    I've read all the threads I could find and it seems like there are several possibilities for what's causing it. Clogged EGR valve/cooler, clogged intake manifold, bad spark plugs, blown head gasket, crappy gas, etc. I ordered an oil catch can, but it will take a few days to get here. I did add some cheap gas before the recent knocking episode.

    I'm not sure whether it's worth it to try to do all the repair options, since my car has so many miles, and because of my previous stupidity. My engine has been burning through oil pretty quickly, probably around 1 quart/2000 miles. And I've been topping it up fairly regularly, but only after I realized it was happening. This is my first car, and I didn't even know cars ate oil until I got the Low Oil Pressure warning a couple years ago, then checked my oil and it was super low. This was at 183k miles, 7500-8000 miles since the previous oil change. I started a thread about it here, and people basically said I probably ruined my engine, so it would eventually fail, just take care of it from now on and ride it out till it dies, etc.

    I assume that since I was such an idiot, and then somehow managed to eek out another 53k miles after running my engine dry, it's probably not worth the effort to try to fix it this time. What do you guys think? I need a car ASAP for work, so I don't have the luxury of spending weeks troubleshooting. Should I at least try siphoning out the cheap gas and adding top tier gas? Or should I bite the bullet and do the whole cleaning of the EGR system and IM, replace the spark plugs, etc? Is there an easy way to check if the head gasket is blown?

    (I should also mention that if I do manage to fix the engine, I still have to replace the brakes and rotors, headlight assemblies, left rear hub and bearing, and fix the horn. All parts I've long since bought but have been procrastinating installing, partially because I didn't want to put it all that effort just for my engine to die shortly after LOL).

    Thanks,
    Grady
     
  2. ChapmanF

    ChapmanF Senior Member

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    You should probably have a leakdown test done immediately so you find out whether the engine has escaped damage thus far and whether there is any chance of any of the 'preventive' repairs you've mentioned doing you any good.

    If the leakdown test shows that compression is compromised, and the engine has already been burning a quart in 2000 miles, an engine replacement is probably the simplest and quickest repair option.
     
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  3. rjparker

    rjparker Senior Member

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    Head gasket long past due when it started months ago. Now its critical path. A borescope will show a clean cylinder and probably coolant. If its far enough along, white smoke out of the exhaust as it revs. Plus oil burning. Most likely needs an engine rather than spending time and money on all the egr, plug, coil, injector fixes that should come with a replacement engine.

    Is it worth it given the hub bearings, brakes and headlights? Only if a better $10k-$15k car is not an option.
     
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  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Have a competent mechanic do a leak-down test.

    boroscope check of cylinders (looking for evidence of coolant) is good too.

    Addendum: NOW I notice this has all been covered, anyhoo…


    If you do hang in there, definitely clean intake and EGR too, or chances are you’ll be blowing another head gasket in short order. More info in my signature.
     
  5. gradyoactive

    gradyoactive Junior Member

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    Thanks for the replies. I drove my mom's new Outback today, and it was so nice and smooth that I decided it wouldn't be worth it to try to repair my old rickety Prius. Her low beams are literally brighter and farther reaching than my high beams lol. Even if I do manage to save the engine, which seems unlikely based on your responses, it probably wouldn't last much longer, and other parts would likely start failing soon too. Plus all the other repairs I've been putting off for so long would be a hassle to complete. Now I just have to try to sell my new/unused brakes and rotors, rear hub and bearing assemblies, headlight assemblies, and unpainted front bumper cover...oof.

    It was a good run, I think, for my first car. I didn't treat her well enough, taking her reliability for granted. I should have done more research on preventative maintenance, used better gas, checked my oil more often and changed it myself. Lesson learned. I also drove her through many harsh Boston winters, specifically during every snow storm while there was a ton of salt on the roads, without one of my front fender liners for the last couple years too. I'm honestly kind of shocked she lasted this long.

    I'll probably buy a new car since right now used cars are basically just as expensive as new ones. I won't be getting another Prius (which feels weird because it's all I've known, since driving my mom's Gen 2 for a few years before buying my Gen 3), because I personally hate the way the newer ones look. I was planning on getting a Corolla hybrid, but now I'm leaning toward the new Honda Insight. I can't imagine the Insight community being anywhere near as big or helpful as PriusChat, though. Thanks again for all the advice over the years.
     
  6. rjparker

    rjparker Senior Member

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    You will find reliability becomes more important than saving money by continuous diy to keep an old car of this complexity running. Assuming your budget permits new vehicles.

    When it comes to gas, there is very little difference these days. All have detergent additives to clean Port Injected valves which are used on the majority of cars including Prius. However many newer cars are starting to use Direct Injection (DI) which bypasses the valves. So those valves get gunked up regardless of gas and generally should be avoided unless the car has dual injection, eg port and direct injection for each cylinder.

    Dual injection.JPG
     
  7. Mendel Leisk

    Mendel Leisk Sand Pounder

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    The intake valves carbon up too I hear; our sons Mazda CX-5 is in that category.
     
  8. ChapmanF

    ChapmanF Senior Member

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    That seems to be the Achilles' heel of direct-injection systems; the fuel has these wonderful detergents in it, but none of it hits the intake valves.

    Hence walnut blasting as a new preventive maintenance item grandpa's car didn't need.
     
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  9. burrito

    burrito Member

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    I've read that the main problem with the Honda Insight is that the high voltage battery tends to fail after only a few years due to the software allowing a deeper discharge of the battery. If that's true, I would avoid the Insight.
     
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  10. Grit

    Grit Senior Member

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    sounds exactly like the lithium packs being sold here will experience.
     
  11. gradyoactive

    gradyoactive Junior Member

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    Oh man, that would be a deal breaker. The HV battery is warrantied for 150k miles/10 years, but I'd be extremely pissed if it died at like 155k. I want my car to last at least 250k miles. And I drive 25k+ miles/year, so 150k is only 6 years. That would be atrocious.

    Where did you read about the failing HV batteries? I haven't seen many people talking about it, or the Insight in general, because barely anyone owns them. Despite looking pretty great on paper, it's largely a failed car model. Honda might even discontinue it soon, when they bring back the Civic hybrid.
     
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