NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10

Oh thsts what it was this morning. It sounded like a rock was bouncing off in the engine compartment but it wasn’t that cold.

 

How many miles? EGR and intake been cleaned?

 

It's at 170k. I haven't done anything besides oil changes since 100k miles. Not sure what the big maintenance interval entails, besides changing the inverter, transmission fluids, cabin filter. All things I can probably do. I just have the synthetic oil change regularly and tires pretty much. The inverter warning came on the other day saying it was too hot, but that was due to the rear seat folded and covering the intake for the inverter I think. The temp has been 55F, not terribly cold. Not sure why the engine kind of shook the other day. I've been afraid to drive it so haven't driven it much. I graduated in January, studying to past my licensing exam so I cant find a new job for another month or so. I was hoping to take the Prius for a roadtrip since I started school in 2018 and haven't had a break since, but it doesnt look likely if the car acts up with all these lights coming on and shuddering. Although the shuddering hasn't come back since 3-4 days ago.

 

EGR (Exhaust Gas Recirculation) components and the intake manifold EGR passages are likely very carbon-clogged. Cleaning is best done by 100K, at the latest. I would get on it ASAP, but if the knocking at start-up continues you may have failing head gasket already.

To see where you're at with that, a leak-down test is best. If that the coolant level is stable in the engine coolant reservoir, that's a good sign. Keep an eye on that as well.

It's my personal opinion that neglecting a carbon-clogged EGR leads to head gasket failure. It's hotly debated here though, so...

Anyway, more info in first link in my signature.

 

Thanks Mendel. Yes sir, knocking may have been my loose Innovited power module that got loose and was scraping the inverter module I guess. Not sure why the knocking was so loud when I started the engine even if it was loose. I haven't felt it since I ziptied i tback in place. 5 years is a good time for a ziptie I guess. Yes I saw the YT on EGR cleaning. Not too bad. My battery might be causing all the lights to come on without starting the car. The start button is not responsive either. Luckily, after turning it off and waiting for 5+ minutes and restarting the lights went off. It's peculiar. The battery is at least 4 years old so it may be time to change. Usually in the desert I have to change the battery every 2-3 years. So far changing the oil on a regular basis and cleaning the air filter was the only maintenance I've done. Even if it's a head gasket issue, I sure hope it's as easy to replace as my Corolla that I had a few years ago.

Now, I must investigate why the car doesnt start and all the lights come on. Not a good sign. Hoping it's just the battery.

 

Have you tested the 12v battery? Or at least put a 4 amp charger on it overnight?
If it is getting weak, weird things happen.

 

If you have check engine light and it is about inverter, then check your VIN number if it has inverter recalls. Not sure from 2010-? Inverter and brake booster is in recalls and campaign for a while.

 

My first post on Prius Chat!

I'm a new owner of a 2010 Prius with 134K. Test drove at a dealership on a cold (20 F) morning outside Boston last week. The car ran great, and the mechanic I paid to do the pre-purchase inspection found nothing of concern other than the need for an oil change (albeit it was just a random shop nearby with good Google reviews as I'm new to car ownership and the dealership was a ways away from me).

Today (a mild 40F), a week after purchase, on start up I hear a brief but very noticeable knocking when the ICE kicks on 10 seconds after starting the car. I drove for 30 minutes, no knocking at any point during the drive. Let the car sit 90 minutes after getting home, and go again to start and no knock, so I hope this is just intermittent cold starts for the time being. From research, it sounds like there could be several different causes (clogged EGR, failing *shutters in dread* head gasket, spark plug issues, intake manifold, etc...).

Besides the Carfax report showing regular oil changes, there is no maintenance history to this car, so I'm not sure where start. My plan is to find a shop that really knows their stuff about higher mileage Priuses. I'm very excited to do some of my own preventative maintenance (I'm totally new here), but this knocking issue and the fact I just bought this car makes me want an expert's eyes to start.

Any general links folks can share for gathering more information on this before I have it looked at? Is there a way I can ensure a mechanic is considering all the possible causes/fixes to this issue? Again, totally new to my car so trying to learn as much as possible right now, and I'm frankly very concerned. There is a 30 day return / 1000 mile warranty, so if there are any nails in the coffin already I should be able to act.

 

Leak-down test is definitive for testing head gasket integrity. If you keep the car, head gasket repair or not, I’d get on EGR cleaning, soon as practical. Info on that in my signature.

 

Check the coolant level, it will gives enough info if you have head gasket issue, waterpump, radiator, etc.
Knocking in the first cold start is a good sign of head gasket too.
EGR clogging symptoms is only when the engine is warm and try to cruise at low speed and the car shuddering from unstable RPM.
Bad sparkplugs or coils are consistent, not only at cold start.
Smell the exhaust too, if it smell sweet glycol, it is coolant smell

 

Another EGR clogging symptom: miles on the odometer. If you've got 100K miles it's pretty much certainty the EGR components (and intake manifold EGR passages) are getting significant carbon build-up.

 

Thanks all.

Had a mechanic look at it yesterday and showed him a video recording of the issue (tried posting a youtube link to it, but you have to post 4 times before you're allowed to share links). There were no codes, and said he would not be that worried if he were me. I explained my head gasket paranoia and he was very skeptical this would be the cause, but also suggested marking the level in reservoir would be a good way monitor (the level is plenty high at the moment).

I mentioned doing a leakdown test, but he dismissed this based on his read of the situation. Can you confirm this would be a cylinder leakdown test, and not a leakdown test where I pressurize the coolant reservoir and measure from there? Confusing as people on the internet seem to test their gaskets' integrity using either, with the latter being a much more approachable DIY... Wonder how much it would cost to just pay a shop to do the former despite their lack of concern.

Point taken on the EGR Mendel. Will get on that soon as I feel more sure this is not a failing gasket. Also seems like now's the time to clean the throttle body, mass airflow sensor, and intake manifold based on what I'm seeing online.

 

Posting again so I can share links...

 

And hopefully post #4 does the trick...

 

Here it is:

 

Honestly with the knock being so brief I'd barely be concerned about it. If I were you I would be doing as the mechanic said and mark the reservoir and monitor it for loss of coolant.

 

ZF3 warranty extension 2010-2012 Prius for cold start engine rattle thru 10 years/150k .
They replace the egr valve and update the egr software. 2010 no longer eligible but maybe yours was already done? Maybe $1000 or so ? If you have to pay for it. Known issue for 2010-2012 Prius. Scary when it happens, can't be good for engine. I'd ask seller to pay for it if you have a warranty or return window.

 

It may be a cold weather problem. That is the only time I had issues.
I used a 16 oz can of Seafoam for gasoline, and so far so good.
Are you losing water? Take a photo for reference. If you are you may have the head gasket problem. I did not, and the additive seemed to work. Maybe it will work for you before you go deeper.

 

Don't punish your self yet. Take a look at the mass airflow sensor first. Clean it with CRC airflow sensor cleaner or pure isopropanol well, don't rub it unless you are very gentle.
I had this problem after my brother made mistake using a contact cleaner that contain silicon on it. It rattles like that for a split of seconds. However, I have no coolant lost and I have 2015 which has much less issue and burns no oil. It is not the EGR if the problem is in coldstart. EGR will start opened only after the engine warmed up.

 

Except: clogged EGR and head gasket failure seem to be steady dance partners.