Are failed HG's really all that common though...?

Some people are just lucky.
And it would depend on how hot the engine got.
I don't believe the computer engine would shut the engine down it if
got too hot. He was just lucky.
I went 301,000 before mine started to go. I replaced it before it cause any damage.

 

Just because we see a bunch here doesn’t mean they’re common.
Might be 1% for all we know.
We do know that the egr circuit tends to gum up over time, but that’s about the limit of definitive knowledge.
And Toyota claims only a small number of gaskets blow and it is due to incorrect programming of the water pump software

 

How can you say the head gasket is fine?

Report back here in 6 to 12 months with a follow-up, then we will all know if his head gasket is fine.

 

Look this does not happen per se to the 2ZZ engine non Atkinson that is in millions of cars on the road the same for a lot of the engines that I've driven for the last 50 years with this marque. It seems to be fairly common in the Prius Atkinson cycle version of that engine I don't know why because it's regurgitating its own puke most of the time it's running just a guess I know I wouldn't function very well operating like that of course I'm a human but anyway. It's common enough that I don't want any part of it if I could detune and made up a 2Z engine from a Corolla and not have to Atkinson cycle it I mean how much gas mileage are we getting from this regurgitating its own puke all the time and massive amounts of EGR being pumped into the intake I don't know I could take a 5 mi to the gallon hit for 4 or 500,000 uneventful miles like the generation 2. It's really that simple The Gen 2's go 500k pretty uneventful for the most part batteries fans tires you know come on normal stuff the few people that have ripped out transmissions and opened them up to six and play with motor generator one or two and all that stuff are so few and far between you have to spend time to look for the write-ups even here on this form that's how rare it is how rare it ever has been whatever but the head gasket on the 2Z Atkinson shoot that's a once a week issue here practically now I don't know how much of the Prius community is on Prius chat but doesn't really matter to me just seems like a poor design the interior is not so good The door panels are terrible on this model all the way up until 2016 so that's a whole 6 years of vehicles that are well to me worthless.

 

Has he had it since new? If not, when did he get it, and at what miles?

 

Don't freak out over the head gasket. Just start putting money aside to repace it.
Just check your oil every time or two you get fuel and check the overflow tank.
You'll notice if it starts going down, and you'll get a knocking when the engine starts.

 

Wait, I assume they sent a notice to all owners telling them to schedule for a free software update, right?

 

in europe, maybe. i think there might be a tsb here. see this thread:

tsb-eg-0127t-1014-sw-update-to-avoid-cylinderhead-gasket-failure.243712

 

In Europe they published a Technical Service Bulletin: TSB EG-0127T-1014 (SW update to avoid cylinderhead gasket failure) | PriusChat

That goes quietly out to dealers, not to all owners. It advises the dealers that a software upgrade "is available for vehicles driving under these specific driving conditions."

So it kind of works like, if you live in Europe, and there's a dealer mechanic who happens to hang out at the same coffee shop as you, and you happen to say, one day as you're making small talk, "you know, I frequently drive my Prius with Long period of engine idle time e.g. taxi use, city parcel delivery, traffic jam, etc., or High percentage of “stop / take-off‟ (go) operation e.g. traffic jam, city / door-to-door driving, etc., or High percentage of high speed / high load operation, or Use of low quality engine coolant, or Vehicle used for towing", and if the mechanic you're chatting with has already had enough coffee and remembers this, she might say "funny, you know, we have a software upgrade available for people like you that might make your head gasket last longer."

And even as aggressively proactive as that isn't, in Europe, it's more than they've bothered to say here.

 

Yeah, 1% who don't have a gen3 with failing headgasket... Of the dozen Gen3 owners I''ve worked with, only one of them has no issues with coolant loss. He changes his coolant often and has an oil catch can, but hasn't cleaned his EGR yet because his wife broke one of the bolts that goes into the block when they tried to remove it for cleaning, so now they're just waiting for warning lights to know it's clogged.

 

There’s one bolt, up at the top, and the rest are studs with nuts. If the rearmost studs (at connection to exhaust manifold nuts and studs are removed, I can’t see the issue. Maybe a snapped stud just scared them off.

 

yes, exactly... Their marriage seems less difficult if they don't talk about it. I didn't get the details because he didn't want to talk about it. But he went to war with rusted out wheel bearings mounts that were impossible to get loose and won, so this EGR problem isn't something that's gonna be that bad once he stops avoiding it. I guess we're all a little like that when we have to do something we've never done before.

 

You are probably hearing the flex plate/dampener at times depending on it's rotation when the engine last shut off might thump extra loud, or EGR valve as well. The HG rattle is much more pronounced and lasts 10-15 seconds...unmistakable.

 

You're right that the head gasket is not the only thing that can cause a cold start knock. If it is happening only occasionally, and especially if it just happens when the last use of the car before cold soaking was a very brief run that didn't warm the engine up, then probably it is the snort-of-water-condensed-in-manifold issue described in this TSB. You can reduce the incidence of that one by avoiding very brief non-warmup engine runs where you then let the car sit cold.

People were first reporting that issue as early as the fall of 2009 for the very newest Gen 3s for the 2010 model year, so it certainly didn't have anything to do with high-mileage head gasket wear or anything like that.

 

Yes... But you can go years without it being a problem... Catch is, you'll destroy the dampener in the transmission if you ignore that rough running at start up and it gets really bad. Once you get up to having to add significant amounts of coolant every day, it's time to stop and get it fixed.

 

Yes. Av 190k life