LOUD Banging/Rattling at Start Up!!!

I couldn't ignore this one. I speculate that some road trash might have blown up under the car towards the end of the last commute, or a rodent or something may have found a place to rest. The 2010s do not have an accessory belt right?, but this could have been located near one of the cooling fans.--

Was the A/C on when the car was started?

 

Sure sound odd, but as one poster mentioned could something have gotten in the cooling fan area perhaps??? You have not had it in for service in the past day or 2 prior?

Sounds like something was in the fan blade area, but maybe a check of that area to see that all blades are intact etc and nothing is stuck inside..PEST, BIRD..etc..

 

Completely baffled as I can see nothing that moves when the ICE runs except a bare pulley, AC and fans are independent of the ICE aren't they?
What would water do?
Was the car moving when it did this?

 

Here kitty, kitty, kitty.

 

Are there any other blind guys in your neighborhood? Are they all accounted for?

Tom

 

You wrote, "This morning when we went to start the car, it started normally, going into NO ICE initially, then after a few seconds the ICE came on and immediately there began a LOUD Banging/Rattling sound from the engine compartment. It was VERY, VERY loud! It was NOT a metalic sound, it sounded more like plastic, but not the plastic piece that covers the head of the ICE, it sounded more substantial than that."

This is NOT what you think it is. This has happened to me twice. What you are hearing is the engine trying to "catch" as it transitions from all-electric to ICE (internal combustion engine). I brought this to the attention of my local dealer and they said this is the first they have heard of it. It sounds like it may actually be an issue w/the engine(s). The sputtering/shuddering you're hearing is LOUD and I wondered if I ruined the engine or not, but just like in your case it did not occur after that. The best thing you can do is to make a note of it and report suspicious activity such as this to your local dealer. They should be keeping track of these issues. If nothing else, it begins a paper trail in case other issues arise in the future.

Other 2010 Prius owners may have had a similar experience. This is a good place for us to share our experiences to get the word out.

 

Hmm, perhaps the intake/exhaust valves where open and it had a little pre-ignition into the exhaust manifold? Just a guess.

 

Mine did the same a couple times. Just like Windows, I powered it off, and back on, and it was fine.

The second time, I just went on my way, and it settled right down.

If it becomes common, I'll head to the dealer with it. But, I'd bet dollar to doughnuts they won't be able to replicate it.

 

Wow,
I think "loud banging" needs investigating, not sure If I could let it go. Sounds stupid, but if it re-occurs, I'd start taping the starts with a video camera.
I've been on the fix-it side, and you really can't fix what isn't broken. That is another way of saying "could not duplicate"

 

I had this happen just after I washed the car during this past weekend. Turned it on, the sound happened, turned it off, turned it on again, sound happened, turned it off, never returned. Though the sound was not distinctly metallic in nature it couldn't have been plastic with the loudness and force the banging was doing. I suspect it was in the transaxle.

Wayne

 

You guy's are spooking me

 

I just though it was me. Had the same thing this last weekend, started when the ICE
came on loud non metallic push the off check under the hood nothing, turned it back on the sound came back but not as loud again off and checking, nothing, turned back on no noise??????

 

Same thing started to happen a few days ago. I noticed it only happens when I dont run the car for severl hours. Very loud noise and the whole dash vibrates. I let it run and it goes away within 7-10 seconds. I have almost 10K miles.

 

It is endemic, a lot of us have the problem, Toyota won't admit it exists. Best way I have found to deal with it is to floor the throttle as soon as it starts which, for me, has always made it quit.

http://priuschat.com/forums/gen-iii...nocking-noise-startup-there-may-hope-yet.html

http://priuschat.com/forums/gen-iii...troubleshooting/70128-rough-engine-start.html

http://priuschat.com/forums/gen-iii-2010-prius-technical-discussion/77856-violent-start-up.html

http://priuschat.com/forums/gen-iii...eshooting/72095-violent-shaking-start-up.html

 

Happened to me for first time today. 2010 III with 3500 miles. 55deg outside, hadn't been driven in about 70 hours. Violent banging from under hood, I thought a neighborhood cat met my fan, but even louder. Went away in 3-5 seconds without powering down. Opened hood and everything looked fine (and no, the fan wasn't running ;-)).

Will bring to dealer soon (Acton Toyota in Littleton MA) and see what they say. Will update, though I expect the usual run-around about being able to replicate the noise, etc.

 

Is this in any way connected to the 'knocking on start up' threads that have been on the site for some time now?

The symptoms are similar. Turn car on - engine knocks/shakes,bangs when it starts. Stop engine and restart and all is well.

If it is then the dealers are aware of it as are Toyota and as are many owners on this forum - including myself where it happened once after being stood for a few days in very cold weather.