How to replace engine coolant pump and thermostat

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Patrick Wong, Oct 10, 2013.

  1. Shazane

    Shazane Junior Member

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    Fellas, I thank you for responding. I know where the CHS relay is at. I've used three meters to get the pump to activate, one brand new and the wire trick. Non of them are working. I know how it should work, but it's like the relay box isn't getting proper juice. Everything thing is plugged back in. I'm simply going to replace the thermostat while I'm at this stage. Yes, the P1116 refers to a sensor and the code may be being tripped due to an air pocket. However, since my car isn't allowing me to trip the water pump, I have no choice but to take it to the dealer, which I dislike doing.
    Thanks again.





     
  2. dragonrand

    dragonrand Junior Member

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    Patrick,

    Just a shout-out to thank you. Last Sunday I replaced my coolant pump, and did a complete coolant replacement while I was at it. This and other posts in this thread, as well as your links to the other posts (by you and others) in other threads, gave me EVERYTHING I needed to know to complete this project successfully.

    The only place I drained coolant from was the valve near the CHRS canister. Because of the posts I had read, I was surprised to drain, in the end, a full 7 quarts from my 2005 Prius. I left the radiator cap on during the initial drain, then ran the pump manually a number of times, which triggered a lot more drainage. Removing the radiator cap allowed still more to drain. Once I thought it was done, I created a seal around the radiator neck with my hand and blew into the radiator. At first I mostly got spray, but suddenly, more legit draining took place. I was happy to get out as much as I could, since my car is at 290k miles, and I haven't changed the coolant in years.

    IMHO, this alone is reason enough to stick with a Toyota replacement coolant pump. I originally bought a third-party pump which came with a paper gasket. When I started doing research on sealing it properly, using the silicon goop, letting it cure overnight, etc., I called the Toyota dealer to ask them how much their gasket was, figuring they'd have pre-treated it with whatever it actually needed. He didn't have one in stock, but he offered to go look inside the box of a coolant pump, which they did stock, to tell me about it. He came back and said it was metal! Sounded strange to me, but doing more research showed me that the metal gasket by itself should seal fine, with no cure time required. SOLD. I went and bought the Toyota pump. (Also, my original pump was still working - albeit noisily - at 290k miles. Would the aftermarket pump last as long? Who knows? I returned it for a full refund.)

    Yes, this funnel was awesome. I bought it for $40 from a local parts shop knowing I might never use it again, and in the end I still think it was worth it. It was still a time-consuming process to refill and bleed the coolant system, but I spilled nothing due to this funnel. Since I paid $50 for 2 gallons of Toyota coolant, I'm happy not to have wasted any.

    I DID run the pump, using the cool twist on Patrick's technique posted by jreed in post #56 here:
    Changing engine coolant | Page 3 | PriusChat

    Although I could tell from the sound the pump made whether it was pumping air or fluid, it was still useful to have the current readout on my meter to confirm objectively what I was hearing subjectively. After a lot of back and forth - turn on heater, rev engine, run pump, check heater (still cool), run pump, rev engine again, etc, etc, ad infinitum - I finally ended up getting, afaik, about 6.5+ quarts of coolant back into it. By the end, the heater was blowing hot, there were no sloshing noises anywhere when driving, and after several days of driving, I've only been able to add a very small additional amount of coolant to the radiator; less than a cup.

    A few other things I'll note:
    • My tensioner pulley had virtually no slop in it at 290k miles - it still spins smoothly and quietly with no vibration. I thought about replacing it anyway, but now, after having removed and replaced the serpentine belt, I know it's no big deal to do it later, if I hear it start making noise.
    • Noise! I can't believe how much quieter my car is with the new pump. The old pump had probably been failing for quite a while, but the increase in noise was so gradual I just assumed that was normal as the engine aged. It was only toward the end, when it sounded like something was rattling and rasping under the hood, that I started investigating and discovered how sloppy the pump was. You could actually see the pulley rattling side to side as it spun. I'm lucky it didn't seize or fail. But I'm still a newbie when it comes to DIY maintenance on cars. I'm pretty proud of myself for tackling this by myself.
    • It took a while to figure out how to wedge the pulley in place so it wouldn't turn as I loosened the nuts holding it to the pump. Once removed, the pulley itself had lots of junk caked onto big portions of the inside edge - it looked and felt like cement. It had to have been pretty out of balance because of it. Fortunately a couple of minutes in the sink with hot water and a stiff plastic brush cleaned it up good as new.
    • I bought a razor scraper for this project, assuming I'd have to clean some gunk off the mating surface for the pump on the engine side to prepare it for the new gasket. Nope. It was nearly spotless. There appeared to be one slightly dirty area that wasn't perfectly smooth, so I took a brand new kitchen scrubby and scrubbed with moderate pressure for a minute, then wiped the whole thing clean with a shop towel. Done. Perhaps the clean state of the whole area is support for two arguments; 1), use the proper Toyota coolant, and 2) use the Toyota gasket and avoid using a paper gasket with the RTV stuff.
    • Overall the project took me a solid 6 hours - but I'm new at this. I struggled with how to hold the pulley stationary for a while. I also lost the tensioner pulley nut somewhere down behind the washer fluid tank at one point, and had to partially remove and twist that around, just to try to see where it might have gone. Thankfully I got it back. I tried at first to avoid removing the under-engine cover on the passenger side, thinking I wouldn't need to get to the coolant pump from underneath the car. I was wrong, and eventually ended up removing it anyway.
    Seriously - did I mention how quiet my engine is now? It's like I have a new car! :-D
     
    #42 dragonrand, Aug 3, 2016
    Last edited: Aug 3, 2016
    blaisep and Patrick Wong like this.
  3. Peter Freudenberger

    Peter Freudenberger New Member

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    This thread is amazing - even 1 year since anyone posted; this still stands as the best source of information I could find on doing a DIY pump replacement. After reading through all the posts, and posts in linked threads, I ended following almost the exact procedure from the YouTube video. A few stray observations that may help others in the future:

    -As others have pointed out - a special funnel kit (search Amazon for "EPAuto Spill Proof Radiator Coolant Filling Funnel Kit") makes this job an absolute breeze. I didn't even have to use the bleed screw, put the car in inspection mode, or mess with the CHRS relay - I just ran the car for ~20 minutes with the heat on blast. Most of the bubbles escaped before the ICE was even turned on, with just a small burst when I'm guessing either the CHRS pump ran of its own accord, or the thermostat opened. After completing the process, driving the car around the block, and letting the engine cool down, I only needed to add ~1 ounce of additional SLCC to the radiator.

    -This job is definitely doable (although it helps to be left handed and/or have small hands) without pulling the bottom engine shroud/wheel well shroud off. Mine were held on with rusted screws and generally a pain, so I just did everything from the top. Job took about 3 hours/4 beers, most of which was spent being bad at getting the orientation of the new gasket + pump correct, and swearing at the idler pulley nut.

    -You definitely don't have to drain the whole engine of coolant to replace the pump. I just pulled the pump right off, and ended up only dumping & needing to replace ~3/4 of a gallon of SLCC. Given all the stories on this forum about how hard the ICE coolant loop is to bleed of air, I think not draining beforehand may have made my experience much easier. It wasn't even that messy - the coolant just poured downwards in a predictable way and into a waiting oil change pan. Of course, you may want to completely replace the coolant for maintenance reasons, but mine was in fine condition.

    -If you're going to replace the idler pulley when you're in there (might as well if your car has high mileage), definitely use a good quality 6-point socket and a breaker bar of some kind to loosen the nut, as others have suggested. I initially started with a crappy multipoint socket, and damn near rounded off the nut.

    One question if anyone reads this:

    During the process, I somehow managed to lose the.... lil 2"ish round thin metal plate thing that sits between the idler pulley and the nut. Does anyone know if this thing is important? Is it just a dust cover of some kind, or is it necessary to properly secure the idler pulley? Everything seemed to run just fine without it, and it does not affect the positioning of the pulley. It doesn't really seem like it's purchasable as an individual part, and my new idler pulley did not include it.

    Srsly, the reduction in sound from replacing a failing pump with a new one is crazy. Sounds like a whole new car! A lot of the discussion makes this DIY sound rather intimidating, but it's really not that bad.
     
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  4. James1964

    James1964 Member

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    The bleeding of air and the pump relay jump part seem pretty troublesome potentially. I might have my mechanic on stand by just in case although i'm sure it feels really good to pull this one off true DIY and hear the quiet.

    Posted via the PriusChat mobile app.
     
  5. Singh.seattle

    Singh.seattle Junior Member

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    How many thermostat prius 2009 have sir?
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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  7. K8A

    K8A New Member

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    Hope this video helps
     
  8. DLC82SV

    DLC82SV Member

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    So helpful! Thank you!

    Posted via the PriusChat mobile app.
     
  9. prius8654

    prius8654 Junior Member

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    How do you know when the thermostat needs replacing (other than taking a long time to get heat from the vents in the winter). Would there be a code or something that pops up? Thanks Patrick!
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P0125 and P0128 might be logged by the engine ECU if the thermostat remains open and the engine does not reach normal operating temperature. I am not aware of a DTC related to engine overheating, but an overheating warning message might appear in the MFD.
     
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  11. sjguy

    sjguy New Member

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    Has anyone tried this method for just changing coolant? I'm thinking about attaching a coolant funnel kit and filling it up first. Then drain about 1.5 gallons from the bottom drain near the storage tank while keeping the funnel filled during the process to prevent air from getting into the system. The downside is some mixing of old and new coolant, but I wouldn't have to play with the relay nor run the engine.
     
  12. gsu13

    gsu13 Junior Member

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    I realize this is an old thread but wanted to ask what else would you change when doing the engine coolant pump? This is purely preventative as my 2005 Prius has 255K miles and the pump (and serpentine and coolant) was last changed at ~150K. As far as I know, I don't hear any issues - no loud squeals or grinding but I've always heard it is best to change the pump before a breakdown occurs. So if I'm doing that, then what else is good to change since the coolant will be drained anyway? I never thought to do the idler pulley and thermostat until reading this thread, so makes me wonder what else is good to change. Any sensors I should be worried about?

    BTW - I was surprised the idler pulley is as much as the water pump - this is from 355 Toyota Darcars in Rockville. I also am doing the transaxle ATFWS fluid and inverter coolant and pump

    P/N Quantity Price Each Description
    1632562010 1 $ 5.31 GASKET, WATER INLET HOUSING, NO. 1
    9091603093 1 $ 21.56 Engine Coolant Thermostat
    1663021020 1 $ 58.36 Accessory Drive Belt Idler Pulley
    161002915783 1 $ 56.69 Engine Water Pump
    9091602570 1 $ 8.44 Serpentine Belt
    G902047031 1 $ 120.10 Drive Motor Inverter Cooler Water Pump
    9043018008 3 $ 1.43 Transfer Case Shift Shaft Seal (Front, Rear)
    00289ATFWS 4 $ 8.45 Genuine Toyota Automatic Transmission Fluid-WS
    00272SLLC2 2 $ 15.40 Toyota 50/50 Pre-Diluted Super Long Life Antifreeze/Coolant
     
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