LOUD Banging/Rattling at Start Up!!!

This happened to me this morning. Exactly as the OP described, normal behavior when the electrical system is booting up, and then this loud plastic clanging sound just as the ICE kicks in. Sounds like a spinning object hitting something else. Went away after 5-7 secs without throttle input. As if the problem wasn't bad enough, it's downright embarrassing if it happened in a mall.

I didn't even take the car out yesterday. I did wash it though but I did not spray water into the engine bay. My car is always garage parked, probably 5 deg C overnight last night. 10003km

Is this a random problem or is predictable? I was also dealing with a buzzing noise at startup (during the electrical startup phase) under the hood last week, but I'm thinking it's tied to the cabin fan. I'd hate to think of this car as a Cracker Jack box, a surprise under hood every time you fire it up.

 

The good news is is that is seems to go away with age. I had it happen to once about a year ago and never since (14K miles now).

 

I had this at 5500 mlies once. I'm at almost 11k now and have not had it since. only ever had it the one time.

http://priuschat.com/forums/gen-iii...304-2010-rattling-in-engine-bay-start-up.html

 

I'm sure I've read somewhere that it was a batch of dodgy coil packs which may have been replaced under warranty at service time?

 

I think it's the ghost of Toyota Quality past...trying to escape.

 

So I explored the other threads and I'm blown away by how common this issue is. Like a few others, I moved by car down the driveway to wash my car, so the ICE ran for 3-5 sec before shutdown. Then repeat to put car back in. Then, next morning, BAM! You get that rough start very much like that youtube video.

I'm glad to hear that some of you have only experienced this once. I had a weird squeak under the driver's footwell while stopped at a light. Somebody thought it was brake pump or actuator!? Haven't heard it for a couple months now. I'll chalk up the rough start to teething pains.

 

I had this happen once last fall when it was about 70 deg F out at the time, probably about 18K miles, after sitting for 9 hours (8-5 work) after a 28 mile highway drive, and I thought the same about the whole animal under the hood thing. I was working kinda in the sticks at the time (figuratively of course not actually in the woods) so it seemed likely. It went away after running the engine for a litttle while and I was a bit shaken by it, definitely different from the annoying buzzing that my A/C made in the summer.

Back in January I started my car up, 23K miles, 7 deg F, sat overnight after coming home from work (28 miles) loud knocking sound. I had enough time to pop the hood and stick my head in the engine compartment. The ICE was running smoothly and the nasty TACK TACK TACK!! sound was coming from between the ICE and the Inverter box right where that Transmission Input Damper Assy and the flywheel are.

I took it to the dealer and they were certain they reproduced the sound I was hearing. I told the service manager I found that a little hard to believe being that it had happened twice in five months and the last time was one week before the service appt. I told him that I didn't blame them for it I just found that very hard to believe.

Being a mechanic I totally understand not being able to reproduce a problem, it happens all the time and it's frustrating for the customer and the service provider. It may be they don't know whats wrong or honestly think that's the answer but I think there's more to it.

 

How many hundred threads are we going to start about this? Can we collate these down into one massive "My engine rattles sometimes" thread?

 

Hi FireEngineer,

Did anything ever come of your noise? I washed my Prius last night and this morning when my wife left for work the sound happened when the gas engine turned on. We turned car off, repeated and the sound came again. We'll see if it continues. I am very tempted to call the service shop and have it looked at.

Thanks

 

Possible solution if this is true my car from new always showed oil up to the full mark. I just changed my oil yesterday and put in the 4.4 quartes as specified in the owners Manuel. The oil level is exactly where this video states it should be which is below the full mark.

Thus far prior to this oil change I have had two instances of this issue posted in this thread.

Please see this link and video. Overfilled oil in a Toyota Prius. | evtalk

 

This is going to sound weird, I had that same issue today, and after washing the car last night too. I used a pressure washer, and gave extra attention to the front air damn and bumper. I normally use a bucket and hose. Not overly concerned about it, but a coincidence how a few happened after washing...

 

Everyone is banging their heads about this. Here is my opinion.

MG 1 is a AC Motor/Generator, I think what is happening for a very brief time 5-7 seconds. Or until MG 1 spins up the ICE. During this brief time.....somehow MG 1 is getting DC current.

What we are hearing is a MG that is sputtering, not spinning, but rocking back & forth. This is what normally happens when DC voltage is feed to a AC motor.

Unless you have heard this before during your life....you would never recognize the sound from coming from your engine compartment.

For those who want to experience this.....take a AC motor, feed DC current to it...it won't spin,,just rocks back & forth. Magnify this by the amount of DC current going into MG 1,,,,,,you will get the idea.

 

This has now happened to me 2 days in a row during the first start in the am. I guess there is nothing new from Toyota regarding this?

 

Just out of curiosity since it is occurring consistently check you oil level, let us know what you find. Thanks

 

Had this happen to me for the first time today (about 34k miles on a 2010). The best way I can describe it is that is sounds like someone shaking a box of rocks.

 

Try starting the car in a different pattern.

Instead of your normal start........put the car in Aux mode for a few seconds. (Press the start button without your foot on the brake)

After a few seconds......then start the car......foot on the brake,,press start button a 2nd time.

see if this changes anything.

 

Oil is full but it is at the end of it's oil change cycle now that you mention it. It's got 9800mi since last oil change. I can't rmember when it did it earlier in the year how many miles the oil had on it.

 

Trouble is now it's been fine the last few days and it probably won't do it again for a few months. Maybe it's a mood thing LOL

 

It's very possible that our Pri are female (only kidding girls) that would explain why they only do certain weird things when they want to, never when we want them to.

 

Blind Guy/and others...I have experienced this very situation. Have you had your oil changed recently? It is a stretch but I was leaving the house this morning...heard the same noise when I started the engine...as I drove down the highway the undercarriage oil panel/cover fell off and was lodged under the engine. There is a TSB on this...dealer will replace under warranty.