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

They also mention rough idle at start-up, but yeah, bottom line: these are all horses-have-already-bolted symptoms: by the time they get off their duffs you've already got blown head gasket.

 

Right but rough idle from a sticky egr valve as described is far different and longer in duration than a rough idle from coolant in the cylinder, which is not covered.

 

The two symptoms seem to have equal billing?



This is all "rearranging deck chairs on the Titanic" though; either symptom is typically head gasket death-knell.

Funny thing, they mention the noise comes from the HV transaxle, which is maybe admission of coolant in cylinders: it's specifically the damper between engine and transaxle that's balking, as pistons struggle to get over TDC.

It seems to me a clever lawyer could argue they're lying to owners, with the underlined portion of paragraph two above.

 

The "Bigfoot" warranty. They say Bigfoot exists but there is no proof good enough!

 

Don't count on warranty repair folks. Your shit will blow a head gasket. Be proactive, cut the loss, get the egr work done, and move on.

 

I'll throw it out there that the 2015 will give the same problems as earlier models. Head Gasket finally gone, and being in the Toronto area finding someone to work on it (disabled so cannot do it myself) without insisting on replacing the engine has been for naught.

It was a good car up til this point!

 

What’s the miles? EGR and intake manifold cleaned?

 

265000 km. Didn't know what an EGR or Intake Manifold was until a couple months ago.

 

The 2015 has the newer pistons and rings so it won't have the problem with the rings
sticking and scoring the cylinder walls. Also, it has been said that they don't seem to have the
head gasket failures from the previous years. Unless that was because it was newer and
they hadn't failed yet.

 

If you get a chance post pictures of the interior of the EGR cooler and valve.

 

Your last sentence rings true.

Doing a leak down test next week, I have a fairly good idea what to expect. EGR was cleaned when the water pump went out in June but I doubt the intake manifold was touched. Just curious at this point if it's going to be just a head gasket replacement or an engine swap (first quote was $7200 at the one local mechanic specializing in hybrids, which sounds at least 3-4 grand too high)

Toyota has been less than helpful throughout all this.

 

Also, if you have them, it never hurts to post the actual flow test results, which you can get by asking the car, as described in this thread:

Techstream EGR valve blockage data

The more sets of (mileage, result before cleaning, result after cleaning) can be added there, the better-informed our estimates can be of how the flow degrades over time.

The car can also exhibit a non-headgasket-related, very occasional rattle on startup, only after a cold soak and if the last previous run of the engine was very brief and did not warm up. You can tell this apart from a headgasket issue as it won't happen consistently, but only in those exact conditions, starting up fine any other time.

That non-HG issue can be observed in a Gen 3 of any age; the first reports were already coming in by October 2009 in the very newest 2010 models, clearly ruling out developed-over-time causes like EGR clogging or HG deterioration. Toyota evidently diagnosed it as a brief snort of condensed water remaining in the intake manifold's EGR passages. That's the issue that led to the TSB named in this thread's title.

 

Will they be putting a bore scope in each cylinder to look for coolant leakage?
Usually between #1 & 2 cylinders.
I guess it's easier & faster, and they make more money to replace the whole engine
than just to replace the head gasket.
Cleaning the intake manifold is fairly easy, you can do that yourself.

 

That's what I'm asking for. If I were not disabled I suppose I could get to the intake manifold myself. Alas ....

 

Okay, I didn't realize that.....
Well, then your mechanic could do it. Shouldn't be expensive, 1-1.5hr for labor?
If the egr ports get clogged, and usually #'s 1 and 2 get clogged the quickest,
you'll have differnt temps in the cyclinder. Some think this is part of the reason for
the head gasket leaking there.

 

You can see the toyota tech's on youtube talk about the piston and head gasket revisions. Toyota essentially released the same part under a different part number and called it an update. They didn't really fix the issue they just slightly improved upon them.

Solutions are easy though.

catch can for catching the water that condenses in the pcv system in the priuses during the winter.to stop cold start knocks, change the oil every 5k with full syn high mileage, clean or disable the egr, if the car burns oil try a piston soak.

Over a weekend for $75 you can essentially bulletproof a gen 3 prius that is running rough and burning oil if it hasn't blown the head gasket yet.

Also grease the brakes of course.

 

Well I just heard that crazy knocking noise for a few seconds this morning....it was 25 degrees outside. Guess I need to schedule a mechanic to schedule an EGR valve cleaning. The regular scheduled oil change at dealership is scheduled this Friday.

 

Mine a 2012 with about 65,000 miles does it on rare cold start in the winter. I know the EGR system is quite clean as I did a thorough cleaning at about 50,000 miles -- It was not too bad -- so in my case it is almost certainly a slightly sticky EGR valve which is a much smaller job than the system. However, deposits on the valve shaft need to be scraped of so it is more than just lubricating the valve drive thread. I will ignore mine till the summer.

 

Note that this whole entire thread was started by a Toyota TSB having to do with a different cause that doesn't mean anything wrong with the EGR system at all. It has a connection to the EGR system, only in that the little EGR passages in the intake manifold are where the condensed water collects, but it's normal for water to be there (it's 13% of exhaust) and in the right cold-soaky conditions it does condense there, especially if the last time the car was used was just a brief run.

So it could also just be that.

 

Hey there,

Sorry - I am not following something. What do you mean about the head gasket? What does that have to do with the brief rough start up?

My car (395k km) started doing this again on the weekend (hasn't happened in 14 years), and am just coming to this thread trying to sort out what's going on. Car threw P0301.