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Blowing coolant

Discussion in 'Gen 2 Prius Main Forum' started by SPURPURA, Jun 6, 2020.

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  1. SPURPURA

    SPURPURA New Member

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    Bought a 2008 2 months ago with 135k miles and have found this form very useful in dealing with its issues, some solved ,some not. I’ve replaced spark plugs, coolant, coolant control valve, thermostat, tightened serpentine belt, burped the system more times than I can count, intake and throttle body gaskets and replaced the fuel injectors. Still seeing codes p0420 and sometimes p1150. Coolant reservoir is over filling and there’s still pressure under the radiator cap. Sometimes it sucks coolant back into the radiator and sometimes it doesn’t. Any suggestions appreciated.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Any evidence of stop leak product, white goop in the drained coolant?
     
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  3. ydpplqbd

    ydpplqbd Active Member

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    p0420 can be cat, upstream sensor or downstream o2 sensor.
     
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  4. Desert Flier

    Desert Flier Member

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    Couple of thoughts. P0420 is more than likely a bad CAT or bad O2 sensor. When you replaced the thermostat did you make sure the bleed hole was on top? Are your coolant fans turning on? When I replaced my coolant I had to massage the radiator hoses for quite a while to bleed all of the air out of the radiator cap and bleed port over a few days. I have a tech stream scanner and I freaked out watching the live data temperature climb after I thought I had bled my coolant. It ran right up to 250 initially quickly. That being said with my experience on other vehicles throughout the years usually when your blowing coolant its a head gasket issue. Sometimes you luck out and it's just a pocket of air. Likewise the head itself could be cracked. Don't want to jump to conclusions but I've gone down this road a few times. You can do an oil analysis for about $20 and that should tell you if any coolant is making its way into the oil system. There is a also test for that as well where you can take a sample of the coolant to check for exhaust gasses. It will pick up even the slightest amount if there's a leak. But you could have a leak in the head gasket that is just pushing combustion gasses into the water jacket and not contaminating the oil. Also on many vehicles a dead giveaway of a bad head gasket is when the upper radiator hose gets rock hard soon after starting the car. For this test you'd want to force the engine to run continuously in maintenance mode. There is a very good video on YouTube on changing a prius head gasket. You sound quite competent and it's not the nightmare of a job that you would think. Just takes some patience. But for a few bucks I'd look into the oil and coolant analysis. Hope that helps a little. Frustrating I know.
     
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  5. edthefox5

    edthefox5 Senior Member

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    Good one Desert on the top rad bleed hole and the hoses.

    It's such a pain to do a total drain on the ICE coolant loop. Some many valves in the system that work against you.

    To lurkers I highly recommend to not do a total drain just dump the rad a few times over a few months time it works great no bleeding necessary and no airlock drama. It has a real good positive impact on the coolant.

    The rad drain petcock in the on the drivers side bottom of the rad kind of difficult to get to as its behind some hoses in the way. Open the rad cap when dumping it. Take it eassy on the rad petcock its plastic. Not necessary to tighten it super tight.

    To get to the rad cap take off the plastic shield on top of the rad and take the cap off the rad and fill it back up. Dont bother with the over flow tank it does nothing on a G2.
    You can leave the screws out of the plastic cover just fit it back on and the hood when closed traps it. Screws have been off on mine for about 10 years. You want to check rad level by taking the cap off the overflow tank level is meaningless the rad could be empty and the tank full.

    Its a good thing to check that rad level after a few miles after dumping it as it settles in. Always open cap when is cold.

    I check the rad level and the oil level on all my cars every Saturday before starting them. That routine has worked really well for me for many years never any drama with my cars.
     
    #5 edthefox5, Jun 6, 2020
    Last edited: Jun 6, 2020
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  6. SPURPURA

    SPURPURA New Member

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    No,but there was green coolant in the system and clear water before replacing with the Asian red.

    The thermostat I removed had the bleed hole a 9:00 and looked still new. Because it had green coolant, cheap spark plugs, tells me that previous mechanics were unskilled. Still not seeing coolant or moisture in the oil. When I got the car it was only getting about 36 mpg and running rough,tried various injector cleaners and only improvement was when they were replaced with new ones, now getting 46mpg. Possibly some were stuck open. When I pulled the intake manifold to replace the gasket, there was a puddle of liquid in the bottom and looked wet inside the head around intake valves.Perhaps the cat is clogged after being run with bad injectors.

    I am using the never spill funnel attached to the radiator, running heater, air conditioning, in Maint mode, squeezing hoses, bleeder opened, jumping the pump circuit . Very frustrating.
     
    #6 SPURPURA, Jun 6, 2020
    Last edited by a moderator: Jun 6, 2020
  7. cthindi

    cthindi Member

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    Since you are in California, you may want to check if warranty is still good for P0420. CA emmissions warranty is good for 180 month(15 years) and 150,000 Miles which you are within.

    Otherwise since it is just 135K miles, you may want to try with oxygen sensors. There is a good chance that the cat is good.
     
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  8. SPURPURA

    SPURPURA New Member

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    So I decided to replace the head gasket. It was needed, when I removed the head their was coolant inside #2&3 cylinders. Took the head to Napa for inspection, testing and cleaning. Came back fine. New head bolts and gasket set installed, replaced water pump while I was there. Spent about $350 on it. Driving now with about 48.5mpg and no more cooling issues. Still getting p0420 code so tried the Cataclean in the tank per instructions. Drove 3 miles and cel light came on, cleared it, got on the freeway for 45 miles at 80mph with no cel. Yay! Straight to the gas station and filled up. After 2 miles cel light came on but when I scanned it, there were no codes stored in memory. Next trip after 10 miles got the p0420 again but car runs great so we’ll see. 9B5B0B9D-7233-4E3A-9DA6-6A9E4373F185.jpeg
     
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  9. ydpplqbd

    ydpplqbd Active Member

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    You may want to try installing an after-market oil catch can between the PCV valve and the vacuum port on the intake. Oil catch can stopped the P0420 codes on my Gen2. Oil catch can functions by catching the the oil blowby, unburnt fuel and water condensation (AKA "Spoils"). Absent the oil catch can, the Spoils are run through the motor and ultimately the exhaust and catalyst. Catalysts do NOT function well with excessive Spoils run through them.

    I have a thread on the install of my oil catch can. If you are interested, then see: Oil Catch Can from Ebay Installed | PriusChat

    PS My analysis of my 1.5l and the cause of the blowby was: gummed/carboned oil ring at a minimum.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Not sure what I'm looking at. Is that some sort of coolant stop-leak product in some of the coolant passages? I've flagged a couple:

    upload_2020-7-13_6-59-33.png
     
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  11. SPURPURA

    SPURPURA New Member

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    No, it was all clean, it’s just how the old gasket was made. The black coating on the metal gasket is missing between the cylinders. I’d say that was the source of the gasket leaking.