Engine Knocking (twice) at Startup - Anyone Else Experience?

Hey all,

Same issues here.

When I started my Prius yesterday morning, the MOTOR sounded like it started just fine but there was also a hollow, plasticky, clonking/thumping noise like something caught in the fan belt being tossed around in the engine compartment. It only lasted for about 4 seconds and the motor continued to run just fine. No warning lights appeared on the dash. The car only has 90 miles on it.

Long story short, the dealer was able to replicate the sound (vindication!) the next day after starting it in the morning and the service manager said that Toyota has no idea what is causing the problem at this point but that they'd document it. Originally the dealer thought it was perhaps a dieseling motor, but I know what dieseling sounds like, and this ain't it and I was proved correct when they heard it themselves, (although they said it only lasted about 2 seconds for them).

I mentioned this issue to the guy who convinced me to buy a Prius and asked if he'd experienced anything similar in his 2010. At first he said no but then he did recall a time when he started his and heard the same noise. He described it as the sound that might occur if one had a squirrel (or other small animal) caught up in the fan belt, which is a better description of the noise, I believe. It only happened once to him.

Knowing Toyota's less-than-stellar reputation for dealing with problems like this, I'm mighty upset. This is the first Toyota I've ever purchased as I'm generally a Honda guy. The thought that I just shelled out $20k-plus for something that has an unidentified/so-far unrepairable problem has me feeling a bit duped.

Hope they work it out soon. When I buy a car I plan on driving it for at least 15 years and don't like the thought that, even if fixed, the issue is putting undue stress on other parts of the motor that might fail at some point off in the future.

 

Oh...

Forgot to add ambient WX conditions.

It was about -5 degrees F but here in Alaska we have engine block and oil pan heaters, which pre-warm motor for starting. Mine was 'plugged in' for about three hours before starting. Plenty of time to warm the engine.

The fact that the motor was pre-heated before starting and because it didn't sound like motor dieseling to me leads me to suspect that the problem is something ancillary to the ICE.

 

I still believe it is an oil/lubrication problem. My problem ran away when I switched to the TRD oil filter and Amsoil oil

 

I'm with you. Two days ago this happened for the first time. Within a second of the terrible noise I turned it off. I popped the hood and video taped what happened on the restart. Horrible shaking and knocking for about 15-20 seconds before it settled to a normal idle.

 

From what you can tell, what kind of damage is that causing?

I am going to do an oil analysis to see if it shows any unusual wear. I will post the results.

 

Re: work around

Thanks. If this happens again I will certainly try this immediately.

 

So nobody knows what kind of damage this is causing?

 

According to Toyota they are aware of the problem, haven't pinned down the cause, don't have a fix, and somehow know it doesn't cause damage. I cannot see how they can claim a problem they don't understand and can't fix doesn't cause damage. Can you?

 

Last Saturday I moved the Prius to get another vehicle out of the drive. I shut it down before the warm up cycle finished. The next morning, I started it up to a shocking racket of ICE noise. It shook so violently, I could see my dashboard shaking and could hear exterior body panels vibrating. I've heard a lot of engine noises from regular gas engines and this was just as bad or worse than a V8 on it's last leg from spun bearings or broken rods. It was around 36 degrees both days. It lasted about 10-15 seconds until smoothing itself out for another 40 seconds or so. The car only has 970 miles!
I called the dealership and the service rep said she heard of the issue before and scheduled an appointment for me next week.

Add me to the list

 

Started the 2010 Prius the other day. Backed out of garage, and as the gas engine started and sounded like it was bound up and couldn't hardly turn over. Very loud knocking sound, like it was completely out of oil or something. Shut it off. Lifted the hood and looked around. Thought maybe something was in the drive belt. Couldn't find anything. Started back up and just as the engine kicked in, had a brief knock and then ran fine. Only a couple of miles from the dealer, so took immediately to the dealer. They checked it out, could find nothing, so I had to pay, and acted like they never heard of this before. After a couple of tanks of gas since, we were getting 48-50 mpg consistently. Now we are getting 44-45 mpg. Going back to the dealer to report the mileage drop. Not happy with this. There is definitely wrong with the car.

 

Get your money back. Toyota is aware of this problem.

 

Yes I think it could easily be the same or at least a related problem. Our cars use a modified Atkinson cycle version of the same 2ZR engine.

This has been happening to quite a few of us for over two years now, it is beyond me why Toyota doesn't step up to the plate, accept responsibility and come up with a fix.

 

I've had the cold start engine rattle too so I understand your concern but I think your mileage drop is probably more due to the increasing cooler temps.

 

They are always like that until government's investigations.
Maybe it leads to the damage to engine or the danger to the safety?

 

I'm SURE Toyota is aware. Too many people on this website alone are having the problem. I'm starting to HATE Toyota. ...and to think I almost bought the Honda Insight! I wish I had ...

 

I had an oil analysis done and everything was good even after 15,000 miles with Mobil 1 extended drain. Copper, Iron, and Zinc was a little higher than the average oil tested at 7.900 miles. They said I could go to 17,000 miles next time(Blackstone Labs). Makes me feel a little better but I still don't want that terrible knocking to happen again.

 

Wouldn't shake if it were only the oil taking its time getting to the top of the engine.

Likely a VVT-i controller issue, as detailed previously.

_______

Oil Analysis Metals:

—Zinc: Alloying element for bearings, Thrust washers
—Copper: Valve train bushing, Wrist pin bushing, Cam bushings, Connecting rod bearings, valve gear train components
—Iron: Most common of the wear metals. Cylinder Liners, Piston Rings, Valve train, Crankshaft, Rocker arms, spring gears, lock washers, nuts, pins, connecting rods, Oil pump

________

Just curious, why would you want to extend oil change intervals that far?

 

About 3 weeks ago upon starting my 2010 Prius IV (8,500 miles) the computer booted up as normal, but when the ICE started it sounded like something was stuck somewhere and made a horrible rattling/thumping/banging noise. I immediately turned the power off and lifted the hood to see if anything was caught in a fan blade or?. Powered up the car again and same problem, so immediately shut the car off. Since I was in the garage and the light wasn't the best, I decided to back the car out in EV mode. Once outside, I shut the car off and restarted it allowing the ICE to start also and the noise was absent. Hasn't happened since and dealer service rep that checked me in didn't indicate he had every heard of such a issue. He insisted taht I need to reproduce the sound before they could diagnose it. Same old bs that dealers always say. Does anyone know any progress on this issue?

 

My VIN # is JTDKN3DU5A0242941. T-SB-0010-12 indicates VIN numbers that have a "B" as the last letter. Assuming this TSB does not apply to my Prius then?

 

http://priuschat.com/forums/gen-iii...n-engine-knocking-startup-t-sb-0012-10-a.html