Changing the prius 3rd gen Engine/assembly.

Discussion in 'Gen 3 Prius Technical Discussion' started by Syed Jawad, Jun 29, 2019.

  1. Syed Jawad

    Syed Jawad Junior Member

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    My 3rd gen prius 2010 was having a problem of Eating Engine oil, the mechanic told me not to change the assembly instead let me have a look inside the Engine bay, pistons n the rings so he can fix if its fixable.

    I was getting sick of the Mobil oil eating problem so I gave him the car and he opened it please have a good look at the pictures and do suggest weather should I change the piston rings n other junky stuff shown in the pics or should I get a new assembly along with water body and injectors (new).

    So after I get it done what engine oil shall I use I want to use mobil 1 5w30?

    Pistons looks like burned I was not expecting this and carbon is all over the place.

    Plus the engine oil was present in the chamber under the throttle body also I have no idea how n why. 20190629_135933.jpeg 20190629_181728.jpeg 20190629_181731.jpeg 20190629_181736.jpeg 20190629_181735.jpeg 20190629_182959.jpeg 20190629_182954.jpeg 20190629_182956.jpeg 20190629_184110.jpeg 20190629_184117.jpeg 20190629_184120.jpeg 20190629_135616.jpeg

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  2. bisco

    bisco cookie crumbler

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    blown head gasket? how many km on her?
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    How many miles or kilometers on it?

    The rust-like build-up is very strange: poor gas quality?

    When you're done with the engine rebuild, you should clean the Exhaust Gas Recirculation circuit, and the intake manifold. And consider an oil catch can. Some info:

    Nutz About Bolts Prius Maintenance Videos | PriusChat

    Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

    Good thread:

    EGR & Intake Manifold Clean Results | PriusChat

    Another:

    Oil Catch Can, Eliminate that knock! | PriusChat

    Somewhat tools worth having for the EGR in particular:

    E8 Torx socket (mandatory)
    E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
    3/8" ratchet wrench, regular and long handle, flex head, you can never have enough
    1/4" ratchet wrench, or 3/8" to 1/4" reducer
    Ratchet extensions: you can never have enough
    Long needle nose piers, straight and bent tip
    Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
    Torque wrench (3/8" and 1/4" both good to have)
    Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.



    Attached is a pdf with revised piston and piston ring part numbers, what Toyota is recommending for excessive oil burning. It also has a part number for a gasket kit (including head gasket), which is a good idea to use.
     

    Attached Files:

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  4. Syed Jawad

    Syed Jawad Junior Member

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    200000km

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  5. Syed Jawad

    Syed Jawad Junior Member

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    Wow ok thank you so much for such a big help in this regard. I will definitely do that. Its 200000kms. Do I need oil catcher after engine replacement ?

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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    The Positive Crankcase Ventilation system is designed to deal with gas in the crankcase. Decades back this gas was just vented to the atmosphere, along with dripping down onto to the road, any condensate.

    Now with more pollution control, the crankcase gas is returned to the intake manifold. The theory is that the gas will pass through the combustion chamber, combust with no ill-effects.

    In practice, at least with the 3rd gen iteration of Prius, along with crankcase "gas" there's a fair amount of liquid that condenses in the low point of the intake manifold, and likely a lot of mist that passes through, into the combustion chamber, to be burnt, but not as efficiently/completely as the gas/air mixture the engine was designed for.

    It's speculative on my part, but I think the airborne pcv mist, coupled with oil getting past the (older style) piston rings, is causing the accumulation of carbon in the EGR circuit to happen faster.

    The EGR circuit has a couple of functions: it reduces emissions, and it keeps combustion chambers lower, by design. However, 3rd gen was the first iteration to have EGR, and owners with say 100K miles or more are reporting significant build-up of carbon, when they inspect and clean the system.

    This carbon has a couple of functions (deja vu): it reduces air flow through the EGR, and reduces the effectiveness of the EGR cooler (basically a small radiator, meant to cool the incoming exhaust gasses). Both these actions lead to a combustion chamber running hotter.

    Of note too: this style EGR was new with 3rd gen Prius, and judging from owner's experience with carbon clogging: was insufficiently tested. 4th gen has similar system, but with much larger passages, and an input that is further downstream in the exhaust. These changes are actually noted in the sales brochures...

    Long-winded answer, but yeah, unless you're intending to repair and sell soon, if you expect to keep the car long term, I would recommend an Oil Catch Can. The OCC is basically spliced into the PCV circuit, so that all the gas needs to flow through it, and it's purpose is to catch (distill) as much as possible of the air-borne mist in that gas, cause it to condense and stay in the bottom of the container, only allow drier gas to pass through. It does need to be periodically emptied. The liquid collect is a strange mix: some oil naturally, but also (and in particular after the winter months in my clime) a watery poultice, cream coloured with all sorts of crud.

    Read through those linked threads, lots of info.
     
    #6 Mendel Leisk, Jun 30, 2019
    Last edited: Jun 30, 2019
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  7. Syed Jawad

    Syed Jawad Junior Member

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    This helped me alot I am in engine market right now and sir I wana thank you for all these things you helped me with, I have also arranged a oil catch can. I will be posting new engine pictures as soon as I get free from the work shop. New engine here costs 1000 us dollars.

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  8. Syed Jawad

    Syed Jawad Junior Member

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    Dear all its about engine oil now. Can I use Liqui Moly AA0W20 in it and the mechanic told me to flush the first one after 200kms so I bought two of them. Is this oil ok for a Prius 3rd gen ???? I will appreciate quick reply as I am in the shop right now buying this.

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  9. Syed Jawad

    Syed Jawad Junior Member

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    Is this Mobil oil ok after engine replacement? 20190701_184831.jpeg 20190701_184835.jpeg

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  10. Mendel Leisk

    Mendel Leisk Senior Member

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  11. Syed Jawad

    Syed Jawad Junior Member

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