Diagnosing Cheap 3rd Gen Buys

Discussion in 'Gen 3 Prius Main Forum' started by Pollymath, Mar 4, 2020.

  1. Pollymath

    Pollymath Junior Member

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    Hi all!

    New Prius owner here. Long-time reader of Grassroots Motorsports, lover of beater cars and cheap transportation. My daily driver truck is killing me with its 11MPG, and I wanted a cheap beater that was still relatively new.

    You'll have to understand, I'm a big fan of cheap cars that don't turn over. It's like I've walked into the local pet adoption center filled with puppies and kittens. I just gotta take them home. I've fixed and driven many vehicles that were sold cheap cheap simply because their owners couldn't figure out why they wouldn't start. Starters, fuses, other ignition issues. With traditional engines, it's usually pretty easy to determine. I once scored an RX7 for a few hundred bucks because its owner blew a fuse while jumping it. Another time I paid a few hundred bucks for a car, brought it home, replaced a battery, found out it needed a bottom-end, sold it a few days later. You win some you lose some.

    When I spotted a 2010 Prius at the local towing lot with a clear title, a set of keys, no external damage and all its fluids I got curious. It was in a No-Start No-Dash Lights No-Nothing condition. We didn't even know how many miles it had! I got it for well...really cheap.

    I called the local salvage yard in advance to ask them how much they'd give me for it if I sent it to the junkyard - approximately $250. Good to know.

    Brought it home, hooked it up, mystery mileage determined: 214,000. Yikes!

    I've research and researched and come to this conclusion about the order of operations for determining the condition of a "dead" Prius:

    1. Charge 12v Battery (mine is dead, it's from 2013, but my truck has got a strong mother-of-a-battery.)
    2. Attempt to Start Car (not from running other vehicle, but a large temporary spare battery)
    3a. If car starts, pay attention to noises from engine that may signify head gasket or other internal issue.
    3b. If car doesn't start, could be dead traction battery.
    4. Grab a PanLong Bluetooth OBDII adapter for $12 and Dr. Prius app. Test battery.

    Now the question will be: if I get this far and determine the battery is bad, is it worth going any further? Is there any way of starting the motor without A) grid charging the traction battery B) reconditioning the traction battery or replacing cells or C) spending $1000?

    From my research, it looks like no. It's a vicious circle, a chicken-and-egg situation of:

    1. Traction battery needs engine running to charge
    2. Engine Needs Traction Battery to Start
    3. Can't determine engine condition without it running.
    4. Can't determine worthiness of investment without good traction battery.

    Could I do a compression test of the motor to determine head gasket condition?

    Thanks all!
     
  2. Nor'easter

    Nor'easter Junior Member

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    First thing to do: look up service history of your VIN @ toyota.

    If the HV battery is discharged, I'd start with an endoscope inspection of cylinders and a leakdown test (turn crankshaft by hand). If engine appears good, then get the HV battery charged (several ways to do that), get her started, then see what the issues are.
     
  3. Pollymath

    Pollymath Junior Member

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    Well, luckily most of the mystery stuff has been resolved: I got her started with help of a strong battery and a better understanding of the power delivery.

    One thing home mechanics not familiar with Priu..Priui? Priuses? Priued? Anyway, one thing I had to wrap my head around is that just sitting here in my driveway the motor isn't going to start until I press the accelerator. It's pretty easy to assume "it won't start" when your just turning the HV battery on off on off.

    I figured out how to do the Maintenance Mode and that allowed it to sit there and idle.

    That gave me time to pull the laundry list of codes while it sat and idled relatively quietly. Codes for EGR, Cylinder Misfire, Catalytic converter, etc. These all sound like "this car has been driven into the ground."

    I've got a compression tester, I wonder if I can just check compression vs a leak down test?

    Any other obvious way to determine if the head gasket is bad or going bad?

    I've got a boroscope so in theory I could take a peak at the pistons and cylinder head to determine if there is any tell-tale signs there while cleaning the EGR system.
     
    #3 Pollymath, Mar 4, 2020
    Last edited: Mar 4, 2020
  4. bisco

    bisco cookie crumbler

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    Look for loss of coolant
     
  5. fotomoto

    fotomoto Senior Member

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    Bought a cheap no-start bike one time that ended up being a 10 cent cracked fuel pump line hidden inside the tank. Yeah, I was a happy camper.


    Approx. 10-12 sec time frame from On to first ICE start procedure.

    Gen 3 are known for HG failures (sometimes spectacularly). Check oil for milky color is one method but doesn't rule out a leak into cooling system. That's usually seen a loss in coolant or high pressure in the cooling system.

    GOOD LUCK!
     
  6. Pollymath

    Pollymath Junior Member

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    My main concern with driving it is that if it does have a bad head gasket, I don't want to force coolant into that cylinder and end up with a bent rod.

    I'd prefer to determine head gasket condition before driving it anymore.

    Would cleaning the EGR system allow for a more gradual decline of the head gasket rather than the bent rod scenario?
     
  7. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I'd do a leak-down test.
     
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  8. Pollymath

    Pollymath Junior Member

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    Here's my new plan:

    1) Tear apart the engine bay to get easy access to the spark plugs, coils, and EGR system. This will not only allow me to clean the EGR, but also start the tear down for a head gasket if need be.
    2) Do a Leak Down Test - (Anyone use the cheap $30 Harbor Freight Leak Down Tester?)
    3) Get Dr. Prius and Bluetooth OBDII adapter to test traction battery. ($12 for PanLong adapter?)

    My thought is, even if the traction battery is dying, it's probably still worth replacing the head gasket myself. We're talking a $90 part on a vehicle still worth $2500-$3000.

    If the car somehow magically doesn't need a head gasket but the traction battery is dying, it'll totally be worth reconditioning it.

    A Prius ONLY getting 30-35mpg in town is far better than my truck getting 12mpg.
     
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  9. dig4dirt

    dig4dirt MoonGlow

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    True.

    Panlong works, I have that one for the Dr Prius app.

    $90? I think a bit more for the set, and most will recommend using new head bolts and such.
    Plus obviously oil change and coolant from that engine tear apart.
     
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  10. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    Sounds like a good plan in general. Like you are kind of eager to get in there and do the work, which changes the economics vs. people who would need to be paying someone else to do it. (y)

    There's really not much to a leakdown tool. As long as you understand how it is supposed to work, you'll be able to understand the results. The gauges need to be sized right (e.g., to read up to 100 psi, even if they only display a percentage or color), and the orifice needs to be right, with no other significant flow-limiting connections in the setup, and it will work. Unfortunately, the people that manufacture them mainly focus on how it looks in the box and underpricing their competition any way they can. The other thing about using a leakdown tool is that part of the test it to listen to / feel / observe where the air is escaping - e.g., coming out of cylinder #2 when you pressurize #1, bubbling in the coolant, air out the tailpipe, air out the intake, ... and the observation there is pretty much independent of the tool used - you're just pressurizing the cylinder and seeing where the air goes.

    Good idea to open things up to the spark plugs as the first step. I'll suggest that if you're doing that, and perhaps before doing some of the other things, you could try pressurizing the cooling system. In some (most?) HG failures, that will allow pressurized coolant to squeeze past the failed HG, and into the cylinders. So much that if you leave it pressurized for a while (e.g., hour) you should be able to detect coolant on a screwdriver or q-tip taped onto one that you stick inside the cylinder.

    If you do that and get coolant confirmation, it will give you more confidence in everything else you're doing as you go through the HG job. Much more fun to work on a problem where you know that your work is actually solving it, vs. maybe not.

    When you finally do get down to the HG, realize that although many report the problem as being with the HG only, a head crack, head warp, and even a problem with the block are all things to think about and maybe inspect carefully for.

    I have not yet touched anything in the EGR for my 2012 due to low mileage (60k). But my understanding is that while the main problem is with the EGR cooler, you can at least get a good idea for the state of clogging by just removing / inspecting / cleaning the EGR pipe / tube. E.g., a 20 minute job vs. an all day one.
     
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  11. Pollymath

    Pollymath Junior Member

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    I see that the Prius head bolts are Torque to Yield, so yea I guess head bolts are required too. Drat.
     
  12. Pollymath

    Pollymath Junior Member

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    Which is more important or more accurate determination of head gasket condition:

    Leak Down Test
    Coolant System Pressurization Test

    I'd prefer not to buy the tools for both. I've got a endo/boroscope already, as well as compression tester.
     
  13. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    If you take the valve out of the compression tester, you can use it for a quick-and-dirty leak-down test. Google "eric the car guy leak down test". He has troubles with his newly purchased gauge set, but makes do, discusses tips-and-tricks.

    No offense, but I would read up a lot more, before diving into a head gasket replacement. I've linked a couple of Gasket Master videos here, that'll give you some feel for it:

    New head gasket replacement video from Gasket Masters | PriusChat

    And @The Critic has a good thread here:

    2011 Prius Head Gasket Failure | PriusChat
     
  14. Pollymath

    Pollymath Junior Member

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    I've replaced probably 5 or so head gaskets so not super concerned with them. Did on a few motorcycles too.

    Thing is, every motor is different. My old 91 Dodge Shadow was definitely much easier than the more recent dual cam motors (and Subarus, ugh).

    I will say however that I've never replaced a head gasket on a vehicle that was A) as new as a Prius and B) not spewing a white cloud of coolant. I've never had to be so precise as needing a leak down tester because those head gaskets were clearly bad. It's a been bit strange to be so concerned about such a minor leak. I drove a 95 Escort for nearly 25k miles on a bad head gasket.

    So if it seems like I'm asking a lot of questions its just because I want to learn the myriad of ways people approach the problem and diagnoses as sometimes the "common way" is not the best.
     
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  15. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    I personally put a very high value on good information when working on hard problems, so I'd do both tests.

    The coolant pressurization tool can be rented for free at most auto parts stores. Maybe the leakdown gauge too. Perhaps not obviously, the leakdown tester will require an air compressor, so if you don't have that ...

    As a very wise friend of mine once explained to me, every time you work on your car is an opportunity to financially justify buying some awesome tools based on the $$ you're saving by doing it yourself.

    Also, on the TTY head bolts, there is a specification to torque them by angle. Actually, first of all the spec is to use a 10mm bi-hexagon socket (although substitutes are known to work - off the top of my head, maybe a 12mm XZN is virtually the same). Then the torquing spec is for 49 Nm followed by 90 degrees, followed by another 45 degrees. This is a torque to angle (TTA) spec of the *procedure*. Sometimes TTA is specified when the bolt is torqued to yield (when it plastically deforms), but sometimes not.

    In many cases, head bolts are TTY, and need to be replaced. In some cases (e.g., as I've seen for my Lexus LS400), there is a specification in the service manual to measure the bolt diameter to see if sufficient plastic deformation occurred, as a go/no-go test on reusing or replacing the bolts. I don't see anything in the manual about TTY or testing or mandatory bolt replacement. If it were me, I'd probably replace them anyway - not very expensive in the scheme of the overall project.

    But then I'd buy a full gasket set, overhaul the head, etc.

    And I know the awesome youtube video makes it look like a HG is an afternoon job, but if I ever have to do it on my Prius, I will watch and follow the video for guidance, but will follow the service manual step by step.
     
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  16. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I've done, um, none. :oops:

    There is Repair Manual info on the whole process; if and when you get into it I can post excerpts.
     
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  17. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    Another thing I just noticed - you can get the engine idling. That's a big step.

    It means there is a 3rd test to consider: what is known as a "block test" - it checks for combustion gases in the cooling system. This would happen on a HG problem that has that leak - cylinder to cooling passage in the head or block. So be aware that some HG failures will give a false negative on a block test like this.



    Lisle 75500

    Similar to other tools, many auto parts stores will rent things like this for free, but you'd need to buy your own testing fluid.

    ---
    Also, if you can pressurize the cooling system (using a freely rented tool) and confirm no coolant in the cylinders, and that would give you sufficient confidence to drive the car without concern for hydrolocking a cylinder, that may get you rolling to better evaluate high level strategic decisions on repairing this thing. E.g., how well does the battery work. Do cleared codes come back, etc.
     
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  18. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    That boroscope might be a good first step.
     
  19. Pollymath

    Pollymath Junior Member

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    My EGR Cooler was so blocked that filling one end would result in NO water (or cleaning chemicals) flowing through. It took days of soaking and two trips the car wash for a pressure washer to clean it out. There are some still some passages on the corners that are blocked, but the majority of it is clear and I wanted the car back on the road.

    Strangely enough, the head gasket appears fine. I'll need to monitor it, but I'm less afraid of hydro-locking the motor after checking the cylinder again for coolant buildup - nothing. The two center cylinders are little more oily, but no coolant.

    Dr. Prius says the battery is OK. Not great (two low modules) but not dead. I'll need to run the "Personnel Subscription" tests.

    I think it needs brakes. Sounds horrible when braking. Shocks too, rides like sports car.
     
  20. Pollymath

    Pollymath Junior Member

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    Car is tagged and insured. Drove it in anger last night. Drove it to work this morning. No check engines lights.

    Still needs a new 12v battery. Cheapest I've found so far is about $175. Powersports batteries are way cheaper, but will require adapters.
     
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