My Journey with a prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 65caliente, May 10, 2021.

  1. 65caliente

    65caliente New Member

    May 7, 2021
    2006 Prius
    Me and my wife purchased a 2006 Prius in the summer of 2014 when gas prices were approaching $5 a gallon. Our current car was a V8 hot rod. Being poor college students we felt it was the logical choice when we saw such a great deal on the Prius in a craigslist Ad for $4500. Despite it having 140k miles we felt toyota reliability would carry us well past 200k. The car already had the speedometer and a/c compressor replaced due to defects.


    The car had originally been owned by a real estate company who had plastered and since removed vinyl advertising covering from the hood, roof and rear bumper. This had reacted with the clear coat badly and after a few years of the vinyl being removed, it started to deteriorate in the sun. This ended up being my first project with the car. I sanded down the roof and hood and applied a color matched basecoat/ clearcoat which I then wet sanded and buffed to a polish. I opted to just replace the rear bumper with a pre painted one as there was already a baseball sized hole punched into it.

    Despite the adhesive from the vinyl accelerating the degradation of the paint I have noticed other Gen 2 Prius with the clear coat failing particularly on the roof. Not sure how widespread this issue is.

    Spiral Cable

    Around the 155K mile mark we lost the ability to use the cruise control. All of the other steering wheel buttons still functioned so I assumed that the cruise control on/off button was either dirty or bad. Turns out the spiral cable inside the steering wheel had gone bad with just the cruise control lead losing signal. I purchased a $20 one off ebay (bad Idea) Replacing it was fairly easy after watching a YouTube video. There is a part attached to the old spiral cable (steering wheel position sensor I believe) that needs transferred to the new one but it was all fairly simple. After making sure the steering wheel was back on straight we once again were able to use cruise control (FOR NOW).

    CV axles, wheel bearings, brake pads, CVT fluid, and Struts

    Around the beginning of 2016 when we had hit the 170K miles mark I was inspecting the front end and noticed grease had been slung inside of wheel well on the passengers side. Upon closer inspection I discovered the boot on the CV axle was torn open. I decided to replace both CV axles just to get it over with and since I was going to be in there I also decided to replace the wheel bearings, tie rod ends, ball joints, and brake pads/ rotors along with the rear wheel bearings, rear brake pads and drums and all struts. I also decided to change the CVT fluid.

    Here are some things I learned in the this process:

    - Removing the the CV axles can be a PITA, especially if you don't have the special slide hammer tool (which I didn't) I had to resort to a carefully placed block of wood and a pry bar behind the knuckle closest to the CVT output or a chisel and hammer on the knuckle to pound it out

    - It is best to just replace both seals on each side of the CVT. The drivers side seal is harder to find as it is less leak prone (not readily stocked)

    - Removing the bearings from the steering knuckle is an even bigger PITA. The knuckle is Aluminum and the bearing assembly is Steel which causes them to chemically glue together after a while. Be sure to have a shop press handy (which I didn't) or a huge sledge hammer with more carefully placed blocks of wood while trying to avoid hitting the knuckle. Same deal with the rear bearings although they weren't as impossible to dislodge.

    - The brake pads STILL had life in them even after 170K miles credit the the R-braking but I replaced them none the less. The front disc pads were straight forward, I made sure to grease them along with the caliper pins. The new rear drums BARELY fit over the new pads even when adjusting them to the lowest position. What was even more bizarre is the drums I got from Oreilly's were not able to be turned to make them fit better even though they were brand new. Apparently you just have to replace them when they get worn instead of being able to turn them.

    - I replaced all the struts with quick struts pre assembled, we will see how they hold up.

    - The CVT fluid was somewhat dark but not much goop on the magnetic plug, very good for 170K once again.


    From the get-go the car was great although the engine sounded a bit loud/ clicky. I just chalked it up to the Atkinson style engine. I did, however, notice that the Oil was quite dark when I regularly changed it and found myself adding more oil than I would like to in between changes (up to a quart every 500 miles!) Turns out either the previous owners or the real estate company didn't know the importance of regular oil changes and let the oil level get to a low enough point causing irreversible damage to the rotating assembly within the engine. This all came to a head when we had just hit 200K miles and were on our way home from a vacation in 2017. Due to the high mileage on the battery the engine was working extra hard going up hills to the point that, even with full throttle, we were losing speed trying to go 75 mph. Out of nowhere we hear an explosion accompanied by an intense vibration which led to another bang and with that the engine was toast. We had thrown a rod straight through the crank case. Luckily we were close to a town with a U-Haul and the Prius had just enough battery left to drive it onto a car dolly and tow it the rest of the way home. After a couple weeks having a replacement motor/ cvt combo with 100K shipped for $600 on ebay and paying a shop $500 to swap the assemblies while I did the rest of the work I was back on the road.
    Here is what I learned from the process:

    - There are ALOT of electrical connectors on the harness but thankfully each connector is different and is pretty straight forward finding where they all reconnect.

    - The High voltage A/C compressor is bolted to the engine but you can unbolt it and hang it off the radiator core support without having to disconnect any hoses resulting in the need for an expensive recharge of the system

    - Right after I received the replacement engine/ CVT assembly I replaced all the tricky components that were hard to get to once the engine was back in the bay. I ended up replacing the water pump, water pump belt, belt tensioner, EGR valve, spark plugs, and oil control valve.

    - I used a fluid transfer tool to put antifreeze back into the motor and inverter. It connects to a compressor and sucks all the air out of the system and then vacuums the new antifreeze back in to the system so there are no air pockets. Very handy.

    - Before the motor was back in the engine bay I decided to replace the coolant mixing valve and inverter water pump both located under the front area of the inverter. I was hoping this would be preventative maintenance but led to big problems as I will explain later.

    Traction Battery

    The battery seemed a bit weak from the start but it got us where we needed to go although it struggled running the A/C and going up hills at times. When the Engine gave up the ghost I decided it was also time for a replacement battery. I found a 3rd gen pack on ebay with 30K miles for $700 shipped on ebay. Everything went smooth except that I forgot the re-engage the safety switch on the battery at first which gave me a Christmas tree on my dash.

    Steering wheel shaft and multi function display fans

    While studying the prius in general I discovered that the steering shaft was under recall and realized that the repair had not been done. I brought it into the Toyota dealership since the repair was free and upon the return of the prius I noticed a weird pulsating vibrating noise under the dash. I assumed that there was dash disassembly in the process of the repair and that a mechanic had knocked something loose. Instead of losing my car for another couple days i decided to investigate it myself. Turns out that there are two fans contained in the multi function display unit. One that is placed directly on the CPU that pushes air to the side and another on the side of the unit that takes the air from the cpu fan and pushes it out of the unit itself. I discovered that the CPU fan bearings had gone bad and the only place I could find a direct replacement was from a Chinese seller on ebay. There was like three layers of circuit boards I had to take off before revealing the CPU fan and there was plenty of dust buildup to be cleaned off the side fan. I scraped off the old thermal paste and added some fresh arctic silver paste. Once back together there was no more annoying noise.

    CV axles, front wheel bearings, spiral cable, and inverter water pump part 2

    One of the more important lessons that I ended up learning was DO NOT BUY cheap ebay parts like I did with the first set of CV axles, front wheel bearings, and spiral cable. Saving money can turn to a lot of headaches down the road. Within 5k miles of their purchase the front wheel bearings went bad again and within 30k miles the CV axles and Spiral cable went bad again. Make sure to get auto part store top quality or OEM parts for longevity. I took a gamble and it didn't pay off. Now the Spiral cable in particular is a bit of a rip off for what it is if you get it straight from the dealer at $350. You can find OEM spiral cables for a bit over $100 in other places, just don't get the $20 ebay one that I did!

    The replacement inverter water pump went out after about 30k miles as well which was almost a huge disaster. We were coming down the mountain from a camping trip and were just getting into town when all the sudden we see "problem" on the MFD. So we pulled into the nearest gas station and pulled the code from the code reader I always have plugged into the OBD port which hinted that there was an inverter coolant system failure. Sure enough peeking into the coolant tank there was no circulation going on. The cheap ebay pump had completely seized. Thankfully we were so close to town when it happened or else our inverter probably would have fried leaving us stranded. Needless to say I made sure to get the premium pump available at the parts store after that.

    Control Arms

    At around 220K miles I started to notice a single knock when I braked and then a single knock when I started accelerating again. It didn't happen all the time but fairly often. Having already replaced the CV axles (twice!) along with the ball bearings and tie rod ends. I figured it could possibly be the control arms since they were still original with the bushings.

    I found the passenger side control arm to be the biggest pain to remove as the pivot bolt that points towards the front of the car was too long and would hit the oil pan of the engine before coming out of its hole. I ended up having to unbolt the subframe from the main frame on just the passenger side and pry the subframe down just enough so the bolt would miss the oil pan. Questionable design. I guess it was meant to be replaced while the engine was out or with the subframe dropped.

    Transmission Mount

    Unfortunately the knocking noise still existed with no change in tone or frequency so I moved on to my next thought being that the transmission mount located under the inverter was the culprit. I read that there was a recall for the mount on my car so after removing the inverter, putting a jack underneath the transmission and replacing the mount I crossed my fingers but to no avail the knocking still existed the same as always...well at least the mount was replaced.+

    - Side note, I found that if you have to remove just the inverter to clamp off the two main cooling hoses to it in order to avoid coolant loss and once you remove the hoses stick your thumb on the top hose barb (the one connected to the holding tank). This will cause suction within the inverter so minimal coolant will spill out of the bottom barb. Lift the Inverter while keeping the top barb plugged and sit the inverter on the ground with the barbs facing straight up. Do the same thing while putting the inverter back in. Using this method I only needed to add around a 1/2 cup or less of fluid.

    Coolant Storage Pump

    Back when my engine bit the dust I thought about replacing the coolant storage pump when I did the inverter pump and heat valve but decided it was working fine and the only replacements were around $200. For some reason at that time there wasn't any third party ones available. In the winter of 2020 I got an error code P1151 saying the coolant storage tank sensor was out of range or something to that effect but I noticed that the pump was not running like it usually did when I turned the car off. Upon further inspection I noticed that the fuse had blown for the pump circuit. Knowing that the pump had been noisy lately I assumed it was the culprit and not the tank sensor. After replacing it with a Dorman branded part, which was much more reasonably priced, and resetting the codes the issue hasn't come back.

    Brake Position Sensor

    In the summer of 2018 while pulling into a parking space the dash lit up like a Christmas tree and there was a high pitch alarm noise. Pulling the code revealed that the brake position sensor had gone bad. Luckily the system worked most of the time so I was able to restart the car and drive it home without issues. The sensor itself attaches the to brake pedal but requires patience to replace as there is very little room to work with. You also have to make sure you install the sensor in the same position as the old one so take note of its position before you remove it. (it has oblong holes for adjustment to mount it to the brake pedal)

    Ongoing Issues

    - Under Dash vent air mixer actuator is starting to give out. Will sit and click when it is trying to move sometimes.

    - The single knocking noise when I hit the brakes or start from a stop is still there (I am out of Ideas)

    - The tire pressure monitoring sensor batteries are starting to die so I always have the low tire pressure light on now.

    (Current mileage on chassis is 250k)
    SFO likes this.
  2. JC91006

    JC91006 Senior Member

    Nov 10, 2013
    Los Angeles, CA
    2010 Prius
    "The single knocking noise when I hit the brakes or start from a stop is still there (I am out of Ideas)".

    Well the suspension would be at fault on this. Bushings would be my guess