Loud clunk when stopping hard and accelerating after the clunk

!!!SOLVED!!! Loud clunk when stopping hard and accelerating after the clunk

Recently at about 84K miles my 2004 2nd Gen Prius has started exhibiting a "clunk" sound coming from what sounds and feels like is the left side of the car.

I am able to reproduce it most times by breaking relatively firmly with heavy steady pressure on the brake. After the "clunk" happens, which I can feel with my foot on the floorboard something actually moving/shifting. When I accelerate after the "clunk" happens, it always happens again, like something is moving back into position.

This also happens often times when making a left hand turn, I haven't heard it when making a right hand turn yet and it has been about 3 weeks of the same symptom, although it has gotten more frequent. I have seen another post about bolts or looseness in the steering shaft, although I don't have any steering loosness that I can detect.

I am hoping someone else can shed some light on what my problem might be and if they have experienced anything similar. Items I am considering are the steering shaft/linkage, bolts for the steering, CV half shaft, ball joint, brakes and suspension. I poked around under the car about a week ago and didn't see anything loose or obviously wrong. I am mechanically inclined and have rebuilt engines, transmissions and am very familiar with cars but this eludes me so far.

Thanks for any help you can offer. Fellow Prius fan.

 

Thanks for the suggestions.

Definitely not anything in my storage area in the back, and the noise is louder outside the car than inside.

I agree with the CV joint assumptions, seems like low miles for a failure, but very possible. Has anyone replaced one on a Prius, I am wondering about the difficulty and if any special tools are needed or any cautious areas. On a standard FWD car, it is usually pretty straightforward, but I don't have a manual to reference yet so I don't know what is invlolved. As far as manuals go for repair, does anyone recommend a specific manual over any other? I have seen posts about Alldata DIY for $16/year which I am going to look into.

 

My plan at this point is to replace the CV half shaft instead of rebuild it and I will report back on my findings and results when I get around to changing it. Unless I find something else when looking for a cause, this makes the most sense

 

You are correct, it is a single "clunk" on braking, but will also occur when making a left turn without braking. There is definitely something physically moving since you can feel it when it happens in the floorboard. Sounds definitely like the left (driver) side and I have driven down the street at 5mph and had people listen on all sides and definitely eminates from the front left. Since no visible problems are evident, the most likely problem is the CV joint which is hidden by the boot. At almost 100K miles, they do have a limited life span anyway and I plan on keeping the car until 200K, so I look at it as preventative maintenance as well. I also wonder if the regenerative braking puts more stress on the CV shafts since they are under tension when coasting unlike traditional vehicles. This combined with a marginal part would definitely cause this type of problem.

I did look at loose suspension, bushings, etc... and found nothing out of the ordinary.

Thanks for you suggestions, I do appreciate them all. I ordered the CV shaft part today (no one has them in stock). It will be here next week and I hope to change it next weekend.

$80 from Kragen in the Bay Area, not too bad.

 

I did what you recommended with the left tire off the ground and the right tire on the ground. I was not able to hear the noise, but I believe it takes a good amount of force for it to occur. I have had CV shafts that seem fine when turning the steering wheel while off the ground and then after they are replaced the problems are gone, so I am hoping this is the cause.

In my experience, the CV shaft usually comes with the axle nut since they are almost always one time use unless they use a cotter pin. Otherwise I will definitely be picking one up at Toyota.

Thanks for the tip about the buffer/spring between the ICE and PSD. If the CV shaft does not cure the issue, I will have a look at that next.

 

The issue happens in electric only mode, so I (hope fingers crossed) that it is in fact the half shaft causing the problem. Part should arrive on Wed/Thurs. of the coming week and I hope to work on it as soon as it arrives.

 

Here is the latest update. I replaced the CV shaft, problem still exists. Disconnected the anti-sway bar, problem still exists. Pulled off both brake assemblies and bought new shims (existing shims had a small metal tab almost torn on on both sides), cleaned, inspected greased the shims and caliper pins, everything is in great condition. I will post pictures of the brake shim when I get a chance.

I spent some time troubleshooting and looking at things further with my wife and came accross a missing transmission nut on the tranny mount on the driver side. So I proceeded to follow the repair manual on how to remove the inverter. I successfully removed it, overall it was pretty easy, just a lot of parts to remove. Once it was out of the way, I could clearly see that the bracket that supports the brake lines and ABS controller is supposed to bolt to the transmission bracket was missing a bolt and not connected!

There was a piece of rubber wedged between the bracket and tranny mount instead of the bolt because the holes didn't line up. This car was in a collision and is salvaged due what I was told was a relatively minor accident, even though the insurance company totalled it out. I have had it for about 3 years and put about 50K miles on it without one problem yet. This must have been a quick fix or someone being lazy during repair. I spent about 15 minutes straightening out the bracket so that the holes line up again and put a bolt back in, along with installing a new nut on stud that was missing one on the tranny mount. All seemed good, I proceeded to put everything together and it was pretty straightforward.

I went to power on the car after reconnecting the safety connector for the HV battery in the trunk and then connected the 12V battery in the trunk. Upon starting the car, I got a red triangle and all of the standard lights like check engine, vsc, etc... Eventually after putting a charger on the 12V in start mode (high amperage), the red triangle went away, but the other lights did not and it will not start or go into READY mode. I can use acc fine, I hear the pump running in the engine, but it seems like there is a battery drain because I have to keep a charger on the car, but this may just be becasue the car isn't starting and it is the original battery from 2004 so it doesn't hold much charge.

If anyone can lend any assistance as to what I may be able to check in order to get it to start again, I would really appreciate it, othewise I will have to have it towed to the Toyota dealer. It seems like when I remove the battery charger off the 12V, eventually the red triangle comes back again, almost like it is too low voltage. I don't know why this would have changed since I disconnected the HV using the safety connector in the trunk area and the 12V before doing anything. I am a little stressed out and hope that it is something relatively minor. When removing the inverter, there isn't much to do other than disconnect some connectors and bolts for the main power feeds, nothing you can reverse or put in incorrectly and I double checked my work.

I have tried disconnecting the battery multiple times for several minutes and tried again with no change. I have entered the service mode and the battery voltage is between 11.6-12.4 and fluctuates, but will stay around 12.0-12.4 with the charger on it. If I remove the charger it immediately starts to go down.

I hope someone has some good tips, I have searched for hours with nothing obvious to try.

 

You were correct, I had not slid the orange traction battery interlock switch down after turning it 90 degress. Thank you very much, this was an oversight on my part.

The car now turns on and goes into ready, but when I shift into drive, I get the Red triangle and it tells me to put it back into park.

Any ideas on why this may be happening now that the hybrid system appears to be functioning ok?

I agree, hopefully the air bags and other components are in tact, the air bags did not deploy in the accident I was told, which I tend to believe since the damage was very minimal, someone was just being lazy.

I am supposed to be leaving for a trip tomorrow of about 350 miles, so I really hope to get this working for our trip, otherwise I will be stuck driving a less fuel efficient vehicle.

 

I found the solution to the red triangle when shifting into Drive. The rear hatch was not closed all of the way. As soon as shutting the rear hatch, it runs without any errors! :frusty:

Patrick, I would like to extend a big thank you for your comment about pushing the connector down, I was about to have it towed to Toyota which would have definitely been at least $100 plus time for them to move a switch. This help with the WAF!

Hopefully I can extend some help the next time someone needs help in regards to changing a CV shaft (drivers side at least), brakes or removing and installing the invertor.