excessive blow by, + head gasket

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by freshedie92, Oct 26, 2018.

  1. freshedie92

    freshedie92 Member

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    I have another thread about my head gasket. I am almost ready to remove the head. but I am wondering If i should just replace the motor.

    automotix has some good motors shipped for 500-600 ( according to their site)

    i recall removing the oil cap and feeling ( quite subjective) a LOT of air flowing. I did replace pcv valve, did not check to see if that helped.

    I checked compression on a cold, and dry engine. I recall somthing like this 100,90,90,90. i know its low, but i figured it was due to cheap compression tester.

    the prospect of changing the head gasket is not a problem. My fear is that I am spending good money on a motor that overheated, has blow by, and 200k mi. The plan was to test remove head, have it tested, and if good resurfaced, new seals etc. then just replace gasket. I would like to hear what knowledgable people have to say. Specifically @danlatu and others

    I should add that i was drove the car 500 mi, power, and overall drivability was fine. Its just that i noticed all my coolant dissapeared, and i had bad misfire after the car sat for a little while
     
  2. Raytheeagle

    Raytheeagle Senior Member

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    I have removed the oil cap on 4 Prii and found excessive air blow by:

    • Our 2010 with about 175 k miles on it
    • @Pedal Logic ’s 2010 with 79 k miles on it
    • @Pedal Logic ’s prius v with 50 k miles on it
    • A rental Prius c with 400 miles on it
    No coolant loss in any of those.
     
  3. freshedie92

    freshedie92 Member

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    that actually makes me feel better, but worse at the same time. I thought the 2010 was an upgrade over my gen 2 lol. I guess toyota made some mistakes on this one.

    Ill call that 1 point for changing the gasket. thank you!
     
  4. Raytheeagle

    Raytheeagle Senior Member

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    We also checked @SFO ’s 07 with 170 k miles on it and it also had blow by and no coolant loss.

    Might just be an Atkinson cycle thing.
     
  5. freshedie92

    freshedie92 Member

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    I might be making false conclusions but....

    Blow by leads to excessive oil passing through pcv, being burned, clogging up egr system, overheating engine.

    I would think it has more to do with piston seals. I doubt it was designed to allow blow by in amounts that would be called excessive by most.

    Either way I feel better about my current trajectory.
     
  6. StarCaller

    StarCaller Active Member

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    what about using oil?
    what about the amount in the occ?

    mine blows pretty strong out of the oil hole, nevertheless, I had only like 2oz in the occ after 5000 miles /
     
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  7. Raytheeagle

    Raytheeagle Senior Member

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    Mine uses a quart every 5 k miles.

    None of the others sampled did;).

    Well not sure of the rental c, but since it only had 400 miles on it, I’m thinking it didn’t :whistle:.

    Hope that helps (y).
     
  8. Raytheeagle

    Raytheeagle Senior Member

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    Remember the Gen2 doesn’t have the egr system.

    So that’s an outlier.
     
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  9. freshedie92

    freshedie92 Member

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    which is consistent with my theory, no egr, no overheating.
     
  10. 05PreeUs

    05PreeUs Senior Member

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    So there are a few things going on here....

    A failed HG will NOT impact "blow-by" in a meaningful way, it will typically present as coolant loss (inter/external), oil and coolant mixing in either of the other, or white exhaust at all times. In rare cases, a HG can fail between two cylinders and the compression readings will be identical on them, but the engine will have low power, potential misfire and generally no coolant loss.

    You cannot tell anything about an engine's overall health by removing the oil fill cap with it running. It is more of a statement about the PCV system design than anything else.

    The ONLY valid test, to KNOW if the cylinders, HG and valves are serviceable is a leak-down test. The instrument is relatively inexpensive, but it does require some form of air compressor. You do as many as three tests, but generally the first gives the needed results:
    1) Cold & dry
    2) Hot & dry
    3) Wet (squirt oil in cylinders and rotate 720*, then test each in turn)

    While the leak-down test is more complex, with the valves needing to be closed and such, it is also THE definitive test of an engine's health or lack thereof.
     
  11. freshedie92

    freshedie92 Member

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    I might have struck gold then. I've got the crack between cylinders
     

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  12. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    That can't be good. :ROFLMAO:(y)
     
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  13. 05PreeUs

    05PreeUs Senior Member

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    It got HOT!

    Did the engine use oil as well?
     
  14. freshedie92

    freshedie92 Member

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    Previous owner did mention that it overheated.

    It appears that was the case. But I was not paying enough attention to tell you how much. I remember it being full, around 500 mi later it was closer to the middle mark. Why do you ask?
     
  15. 05PreeUs

    05PreeUs Senior Member

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    Overheating severe enough to damage a HG is also likely to have taken the spring out of the piston rings, causing compression loss and elevated oil consumption. Hopefully that did not happen.
     
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  16. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    There's a Technical Service Bulletin on the 2010 oil rings. First they do an oil consumption test, and if you "pass" that, they replace the rings, and the pistons, and check all the cranshaft bearing tolerances while they're in there. Has to be under 60K miles, which is usually too early for the failures. :rolleyes:

    The replacement piston rings indicated in the TSB are the ones that come standard in 2015 Prius. I did some research on the McGeorge Toyota parts department site, regarding the various model years, piston and ring part numbers:

    2010~14 piston ring set part number: 13011-37110
    2010~13 piston part number: 13101-37120
    2014 piston part number: 13101-37240
    2015 piston ring set part number: 13011-37260
    2015 piston part number: 13101-37240
    2016/17 piston ring set part number: 13011-37270
    2016/17 piston part number: 13101-37250

    It's a little tricky, but if you read through the above, look at the various combinations that were used over the years, I think it says that you can put 2015 piston rings (the ones specd. as replacement rings in the TSB) into a 2010 piston, they're compatible.

    Also, @Ragingfit has said he thinks the 4th gen piston rings are also compatible, though there's no paper-trail of parts numbers to confirm that in the TSB's. If they're cheap enough, maybe get a set of both the 2015 and 2016 rings, confirm?

    Note also: the tsb instructs to replace the pistons too, which is a bit involved, requiring heating to separate them.
     

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    #16 Mendel Leisk, Oct 30, 2018
    Last edited: Oct 30, 2018
  17. freshedie92

    freshedie92 Member

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    As if I needed more stress in my life lol. It's better to have that info now that the block is sitting there though. Thank you so much!

    I am looking at a tsb regarding oil consumption and beginning to think about changing out the rings. Problem is I have never done a bottom end. Would you have any idea if I could just replace springs and rings and not have to resleeve walls, or replace pistons. Like I said it's a new world to me :(
     
  18. 05PreeUs

    05PreeUs Senior Member

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    Look at the walls, if you can clearly see strong "cross-hatching" on the walls and it is fairly uniform from top to bottom AND there is no apparent damage to the pistons, you can simply re-ring it (pull pistons, clean, install new rings, oil everything and re-install). You could also move to the parts in the TSB, either way, if the cylinders are uniform and undamaged all they need is a LIGHT wiping around with an oiled scotch brite pad or similar (some OEMs say you don't even need to go that far, but I've not tested it).
     
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  19. freshedie92

    freshedie92 Member

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    Funnily enough I was just looking at that! Mendel you are amazing, thank you for all your help. The thing that sucks is I bought this thing to be a cheap car, time for more research. My old red prius is looking better and better to me now bahaha!

    Any idea if I can ruuse pistons, and use 2015 rings? Pistons sound expensive :(
     
  20. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    Well that's what I'm thinking, looking at the part numbers I listed. You'll see the changes in rings and pistons don't always happen tandem. In 2014 piston the piston is changed, but it still uses the old rings. Then in 2015 the piston remains the same, but the rings are revised. What this says to me is that they're all interchangeable:

    upload_2018-10-30_9-30-10.png

    This is from research I did at McGeorge Toyota. I'd enter my vehicle as a 2010, 2011, 2012 and so on, and for each year noted the parts numbers for pistons and rings. Hopefully their database is accurate. Before taking the plunge, maybe do the same exercise on the more official Toyota parts website. I really think they're all going back to the same source though.

    And again, @Ragingfit says you can also use the 2016/2017 (4th gen) rings, p/n 13011-37270. Perhaps he'll notice this and comment, what's advantageous, going from 2015 to 2016 rings.
     
    #20 Mendel Leisk, Oct 30, 2018
    Last edited: Oct 30, 2018
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