2010 Prius with Misfiring/Head Gasket/Coolant Issue

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by cd216513, Jul 9, 2020.

  1. cd216513

    cd216513 New Member

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    Hi all,

    Unfortunately, our 2010 Toyota Prius is experiencing the misfiring/head gasket issue at 190,000 miles. We weren't aware of this seemingly well-known issue until after we started getting symptoms and took it to the dealer. Surprisingly, the dealer didn't seem to be aware that this was somewhat common. They didn't give us a lot of details of what was going on other than our EGR was clogged and they recommended that it be replaced. They quoted us $2,000 for that repair, so I opted to bring the car home and do it myself. Later that weekend, of course the codes start showing up for misfiring on cylinder 2 and 4. So I dig right in and clean the EGR out. After getting everything put back together, cylinder 4 looks good, but cylinder 2 is still getting some misfires. At this point, I call the dealer back to see if they had any ideas. They said they forgot to tell me that they also recommend replacing the intake manifold with a newer model that helps prevent these issues, and I'm also tired of looking at the car at this point so I take it back down to have them do that repair. They quoted me roughly $750 for this one. After a couple days down at the shop, they call me up and tell me that I am losing coolant as well. I assume that this is the head gasket issue that's covered pretty prevalent around here, so I was anticipating a head gasket replacement. They call back later with updated information, and say that the cylinder head itself is cracked on cylinder 2 and it's not the head gasket. Obviously, they recommend I replace the engine at this point. They are quoting $4,500 for this, which is a challenge since the car itself only has a trade-in value of about $4,000.

    First talking point - Is it possible for this major issue to actually happen? I haven't noticed any other threads here with cracked cylinder heads, just blown head gaskets... I was really surprised to hear this result. I would have expected a gasket to go first. We never saw the overheating warning, no white smoke, and I did not notice any froth in the oil last time I checked.

    Second talking point - We were actually getting ready to do a trade in on this car in less than a month; We had already started research for our next vehicle... with this repair costing more than the trade-in value of the vehicle, we're between a rock and a hard place. What would you all recommend we do about this? Is it worth trying to find another shop that could do an engine swap cheaper? Should we try to trade in as-is? Should we give up on the new car, do the repairs and drive this thing further? My concern with this last option is that we will likely have to replace the traction battery somewhat soon, and who knows what else at this mileage.

    Thanks,
    cd216513
     
  2. bisco

    bisco cookie crumbler

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    1) yes, it is uncomon but possible. or they might have cracked it.

    2) the only other alternative is a private shop. maybe a salvage engine would be a cheaper option.
     
  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Properly flowing EGR is paramount to keep engine temperatures down. When the EGR (and it's passages in the intake manifold) are bunged up with carbon, temps go up. Typically the first intake manifold EGR passage to fully clog is at cylinder #1, as evidenced by pdf attached to first posting in this thread, by @ArmyChief:

    EGR Cooler Cleaning - PICS | PriusChat

    And the EGR's ALL clog. Funny that Toyota doesn't know about this. And yet for 4th gen, they make a point in the sales blurb to say "revised EGR"?

    Somebody should take Toyota to court for this bare-faced lie (highlighted):

    upload_2020-7-9_13-52-37.png

    The solution is to clean the EGR and intake early, before the carbon build-up get bad, say before 100K miles, then maybe repeat every 50K. But Toyota is in "cover our @ss" mode, so the reports keep coming in.
     
    ArmyChief and SB6 like this.
  4. The Critic

    The Critic Resident Critic

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    Without engine teardown, I am not sure how they arrived at the conclusion that you have a cracked cylinder head and not just a blown head gasket.

    I don’t agree with the EGR being related to the head gasket failure, but everyone is entitled to their opinion.

    My recommendation is to trade-in as is and proceed with the new car. It is difficult to justify head gasket repair at this mileage unless it is DIY; the cost simply does not make sense.

    The cost of the hybrid batteries also increased by 50% earlier this month so if the hybrid battery dies soon after, you will be in an extremely bad spot.
     
  5. cd216513

    cd216513 New Member

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    Thank you everyone for the feedback! My wife is leasing a RAV4, since it was critical to get her back into a car while we figure things out here. The dealer only offered us $500 for the Prius, so naturally I declined and I'm going to look into options for getting this fixed up and sold.

    The dealer said they saw the cracked cylinder head by sending a camera down. Would they have been able to see a cracked cylinder head via endoscope?
     
  6. The Critic

    The Critic Resident Critic

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    I find that hard to believe unless the damage to the cylinder head was massive.
     
  7. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    Almost impossible that they would see the actual crack. But if coolant were leaking into the cylinder, it would have the effect of cleaning the carbon (*) off the inside of the cylinder / piston / cylinder head, and maybe they noticed that. And that could be caused by head warp, head crack, or failed HG. Maybe the location of the cleaning effect may direct them to one vs. the others. But ???

    Still, I'm in general agreement that the dealer is not to be trusted, and moving on to another car, selling this one to someone who can deal with it themself, will be the better option.

    (*) while being vaporized by the combustion in the cylinder, the boiling of the leaked coolant would have a cleaning effect on the carbon deposits.
     
    #7 2012 Prius v wagon 3, Jul 16, 2020
    Last edited: Jul 16, 2020
  8. Rathmon

    Rathmon New Member

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    I had the exact same issue with my 2010 at 175K miles. Cylinder 2 & 4 misfire, overheat, and no coolant loss. Replaced the water pump and thermostat, cleaned intake manifold and throttle body, then the EGR cooler system. Cylinder 2 was still throwing misfire code, so knowing that it was probably a head gasket issue, I gave a sealant a try before a more drastic fix. (This is specifically since I had no coolant loss!) I used Bars Leak Carbon Fiber Head Seal, drained a little coolant first, and manually pumped the hose (with the coolant breather open) to get it mixed a little before starting the car. It took less than a week for it to seal the gasket, and currently has been over 2 weeks without throwing the code! (Used to throw it daily).
     
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