08 cylinder head warp tolerance

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Nate Glenney, Nov 20, 2014.

  1. Nate Glenney

    Nate Glenney New Member

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    I have a 2008 Prius (~240k miles) and have been experiencing some very rough running conditions. I've been going down the list and scouring my service manual for common causes of most of my issues, but my main concern is my cylinder head. I am in the process of replacing the head gasket, which I've already concluded to be bad, but my question is does anybody know what the warp tolerance is for these heads? I've searched Google and other auto forums for hours and cannot find an exact answer to this. I know many other 4-cyl Toyota heads has a tolerance of ~0.002", but seeing as how backwards certain maintenance is on a Prius compared to other conventional engines, I wanted to double check to be 100% sure.

    And I realize that trying to save this car with as many miles as it has may seem like a waste of time and resources to most, but it's more of a hobby project at this point and I just want to try my best at trying to save it, regardless of the final outcome. Thanks all!
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You are correct, the warp spec is as follows:

    0.002" when measuring the bottom that faces the cylinder block
    0.0039" when measuring the intake and exhaust manifold faces

    If the cylinder head is warped the block also may be. Rather than go to the trouble and cost of rebuilding, I think it would be much easier and cheaper to replace the engine with a used, relatively low mileage one from a salvage yard. Good luck.
     
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  3. Robert Holt

    Robert Holt Senior Member

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    Can head and block be milled flat on the Prius engine? Feasible?
    I have not read other posts on warping and head gasket failure on high mileage Prii, so is this common or quite rare?
    Many engines have gradual warping over time depending on heat and usage; is that pattern also true for the Prius engines? Anybody know?
     
  4. northwichita

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    [QUOTE="Nate Glenney, post: 2104211, head gasket, which I've already concluded to be bad, [/QUOTE]
    Am interested in how you got to this conclusion, and what the valve clearances are on your engine. In comparison, my engine had some odd wear on the valves , tight intake and loose exhaust measurements , at your mileage.
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That certainly is "feasible", you just send the head and the block to a machine shop. However when you find out their charge to do this, plus the cost of the replacement parts to rebuild the head and block, I think you would decide it is not a financially practical move when you have the easy and cheap alternative of buying a used engine for ~$300.
     
  6. Nate Glenney

    Nate Glenney New Member

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    Patrick, where would you recommend searching for an engine if I get to that point? (I'm getting close, seeing how much of a pain in the a** this as become) I've never had much luck on eBay for major engine components, let alone at an affordable price.

    northwichita, I guess I can't say for 110% certain that this is concluded to be the problem, but I figure with the amount of coolant in my oil (and vice versa) that this is a good starting point, but as Patrick mentioned, if I find many more problems the deeper I go, I might just say screw it and get a cheap motor. I was just held up because I wasn't sure how much warp I could get away with without having to buy a new head. Starting to look like a new engine might be my only route at this point
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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