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Gen 4 Engine Mystery blown head gasket.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by johnnychimpo, Dec 7, 2022.

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  1. johnnychimpo

    johnnychimpo Active Member

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    Background. I upgraded my gen 3 for a gen 4 engine to avoid the head gasket issues.
    But here I am. so I got this engine JDM when I got it it had a slightly bent valve cover gasket bolts
    no problem installed it ran great missed a hose clamp and it overheated pulled over added coolant
    and tightened the hose clamp fast-forward 20 k miles and 10 months of trouble free driving.
    I first noticed milky residue in the oil catch can no big deal lots of rain lately figured it was condensation.
    I noticed the car has been getting warm, not overheating but operating out of normal range. normal is 195.8 but now has been getting to 203 208F. I got gas this morning did my normal check oil while gas is added at pump.
    I notice the milky white goop on the dip stick MF! coolant is slightly low not much then I check the oil cap same and then hose on top that goes to the snorkel. Seems confirmed to me, head gasket blown. Now the mystery I don't have rattle start up so where else can the head gasket be leaking??????? All I can think of is this engine was in a car that was wrecked so bad it bent the bolts on the valve cover gasket and with the brief overheating it warped the head or caused the head gasket to move just enough for it to leak. What do you guys think this engine has 90 K miles
     

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    #1 johnnychimpo, Dec 7, 2022
  2. bisco

    bisco cookie crumbler

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    how many miles did you drive it before noticing a problem?

    certainly worth a leak down test to confirm
     
    #2 bisco, Dec 7, 2022
  3. johnnychimpo

    johnnychimpo Active Member

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    about 2k
     
    #3 johnnychimpo, Dec 7, 2022
  4. bisco

    bisco cookie crumbler

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    maybe something was already wrong with it, any warranty?
     
    #4 bisco, Dec 7, 2022
  5. johnnychimpo

    johnnychimpo Active Member

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    I dont have the tools for that. any other suggestions.
     
    #5 johnnychimpo, Dec 7, 2022
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  6. johnnychimpo

    johnnychimpo Active Member

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    I dont think so I would need to check doubt it, its been a year since I got it.
     
    #6 johnnychimpo, Dec 7, 2022
  7. johnnychimpo

    johnnychimpo Active Member

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    they dont warranty self install
     
    #7 johnnychimpo, Dec 7, 2022
  8. bisco

    bisco cookie crumbler

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    idk enough to suggest another way to test the hg. maybe just keep watching the coolant, and make sure it's not leaking somewhere
     
    #8 bisco, Dec 7, 2022
  9. johnnychimpo

    johnnychimpo Active Member

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    So where can this goop be coming from its in the engine. all over the valve cover gasket in the oil dipstick. Coolant was low just slightly. I just noticed since the last oil check so not that long ago.
     
    #9 johnnychimpo, Dec 7, 2022
  10. bisco

    bisco cookie crumbler

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    any white smoke? would gasoline cause the white? how do the plugs look?
     
    #10 bisco, Dec 7, 2022
  11. johnnychimpo

    johnnychimpo Active Member

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    no white smoke going to pull the plugs today. Like I said I think this is super early as there is not rattle startup and barely any coolant gone to confirm it is barely low. Im working on the leak down tool what should the presure be at??
     
    #11 johnnychimpo, Dec 7, 2022
  12. Paladain55

    Paladain55 Active Member

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    So you replaced the engine to avoid head gasket failure or you had head gasket failure? But yeah man if you overheated the car once chances are the head gasket is already a goner. Especially if you have the froth every where. Try the coolant sniffer test and the leak down test. If you fail it looks like you can do a head gasket too. You will have to check the block and head for warpage above the acceptable limit when you do. Should be good to go after a head gasket though. Try not to drive too much with the bad head gasket. Its terrible for the motor.
    Also, the head gasket issue is completely avoidable. EGR system cleanings or disabling the egr system are the requirements for avoiding head gasket failure.
     
    #12 Paladain55, Dec 7, 2022
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    Seems like a lot of reports, with gen 4 engines transplanted into 3rd of overheating. @Ragingfit mentions to cut the jiggle pin on thermostat, not optimum maybe, but helps?

    That doesn't sound good. Change the oil and continue to monitor?

    You have a leak-down test gauge set?
     
    #13 Mendel Leisk, Dec 7, 2022
  14. johnnychimpo

    johnnychimpo Active Member

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    it half pulled appart already. what is the warp tolerance for the head to get it or not get it machined.
     
    #14 johnnychimpo, Dec 7, 2022
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Not 100% sure the cyl head one has warp spec. Will check. It might be same as block? That spec is noted.

    Addendum: cyl head warp specs in that third one.
     

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    #15 Mendel Leisk, Dec 7, 2022
    Last edited: Dec 7, 2022
  16. ChapmanF

    ChapmanF Senior Member

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    I have had, over the years, a few random passing incidents of a bit of froth on the filler cap and dipstick. It can happen when the weather conditions are just right for some condensation to form in the crankcase. If you can wipe it away and it's not a recurring thing, and there are no other reasons for suspicion, that can be all it is.
     
    #16 ChapmanF, Dec 7, 2022
  17. johnnychimpo

    johnnychimpo Active Member

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    to confirm im thinking of connecting air compressor into the cylinder and see if I get bubles in the coolant tank. would this be a good test?
     
    #17 johnnychimpo, Dec 7, 2022
  18. ChapmanF

    ChapmanF Senior Member

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    Not sure. Head gaskets can fail (supposing, just for now, that's what happened) in different ways. They need to keep coolant away from oil away from cylinders. If a gasket fails between a coolant passage and a cylinder, your test would give you coolant bubbles. If it fails between a coolant passage and an oil passage, you could get milkshakes but no bubbles from this test. And so on.

    What you're talking about is essentially a leakdown test without the leakdown tester. If you were doing a leakdown test, you could concentrate on which cylinders gave concerning readings, and then listen (manifolds, crankcase, coolant) for sounds of where the air was going.
     
    #18 ChapmanF, Dec 7, 2022
  19. johnnychimpo

    johnnychimpo Active Member

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    copy that. I got the tool for the job so I will do this tonight.
     
    #19 johnnychimpo, Dec 7, 2022
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  20. johnnychimpo

    johnnychimpo Active Member

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    So I pulled the plugs and they are clean. I got the leak down test tool and used it to blow air into the cylinders and held it with a wrench as the compression was trying to crank it over. in any case no air bubbles in the reservoir tank. at this point no sign of blown head gasket. is there any other place where oil and coolant can mix? Im out of ideas, if you have a suggestions im all ears. Im going to put it back together and just monitor the coolant. I will also change the oil. I take it if contamination is serious I would see water come out when I drain the oil right?
     
    #20 johnnychimpo, Dec 8, 2022
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