Is Head Gasket failure common in Gen 3?

How is this explained?

And once again,
WHAT is the scientific explanation of: how is decreased EGR flow (with out a CEL showing a problem) doing anything in regards to the head gasket?
This car has two O² sensors, a knock sensor and a modern ECU, all designed to keep the engine clean and safe.

Maybe the relationship is all hearsay cooked up by clean-freaks.
My hearsay is 2 dudes that rack up the miles on Gen3's (both +400k miles) and have never done this 'Cleaning'.
Have any other HIGH mile Gen3's reported not doing this cleaning?

I'm guessing the dudes that never drive above of the 'ECO' display may have the clogging problem, if it exists.
Knock at a cold start up is definitely a serious problem and harmful to the head gasket.

Side question: What triggers a CEL for an EGR problem? Is it just the feedback of the EGR valve not opening as commanded?

 

I always appreciate a bit of skepticism... I've seen many dozens of posts related to this Gen3 EGR = Blown headgasket risk issue. Also Toyota issues a service bulletin and this thread has lots of valid references of where to learn more. But it seems like you're comfortable with where you're at and don't want to learn more. So it's all good...

 

I do want to learn more. I do, I do, I do!!
"Toyota issues a service bulletin..." Please post a reference to this!!!

 

Clogging the EGR has nothing to do with driving slow. It's a combination of how cold the coolant is and how incomplete the combustion. Incomplete combustion comes from things like high RPMs, rich mixtures (wide open throttle), oil burning and bad spray patterns from the injectors. An Italian tune-up would probably make things worse.

I posted some SAE articles and links to research papers regarding EGR cooler deposits and EGR vs combustion. They are in the other EGR threads.

Pixel XL ?

 

I don't have the free time to repost old information every time there's a new EGR thread. That's why it's a really good idea to read completely the links we serve up for you. Or do your own search. I also wish one of the admins would STICKY an EGR thread.

Pixel XL ?

 

He’s from Missouri, so you have so show him exactly where things are for it to be true.

But I do highway driving as 95% of what I do and not at 35-55 mph .

Just did a trip down south where speeds of up to 80 mph were common and a trip up the grapevine had put our 2010 with 192 k miles to the test. But it did well:



This includes LA traffic, some Bay Area traffic and driving in and around Palm Springs.

I bet even with this trip involved I will find similar deposit levels in the egr circuit at 220 k miles when I perform the job again.

 

I wonder what type of driving makes EGR issues more or less likely?

 

Using top tier gas helps lengthen the time between cleanings.

HydroCarbons are a byproduct of combustion. So they’ll always be there. The cleaner the combustion, the slower the buildup.

 

yes, Mr Expert, but there is no rich mixture at WOT in prius.

 

Oh course it did well! And so would mine at 182k miles (and no EGR dikin) !
It's a great engine design linked to a great hybrid drive system!

With the ECU controlling the exhaust emissions and the VVT (which controls the engine's effective compression ration), this engine acts as a pseudo-Atkinson cycle engine.
All these systems make it one of the most efficient car engines in terms of power extracted from the gas.

However you will always see deposits in any engine's EGR system. It is after all dealing with the 'sewage' side of the engine.
Make all your house sewage pipes squeaky clean and "100k miles" later you will see "deposits".

"Top Tier gas" has less Fiber and burns differently? Where are your references that statement?
I thought it was only about a regulated amount of detergents in the mix.

Really? The Carb doesn't have enrichment ports at high power?
What you do get at WOT is max EGT and max flow rate of this hot sewage, but it is still 'clean' sewage, and may contribute to keeping passages flowing adequately.

 

Yes, Mr Contributor. But do you really think that one oxygen sensor guarantees that all cylinders are always lean of stoich? Also, do sensors last forever? Do you understand open loop? What happens when the injectors collect deposits and become unbalanced? Have you heard of an injector being stuck open?

Pixel XL ?

 

OMG, "the carb" - there's a carburetor on this engine? LOL

Pixel XL ?

 

Perhaps EGR clogging is inevitable. I can't recall anyone here with higher miles that hasn't had clogging.

Apart from a couple of cabbies that keep getting trotted out...

 

It’s there.

They just take the Sergeant Schultz approach.

 

Google "thermophoresis EGR". Thermophoresis is the deposition of soot particles by condensation of the gasses onto the EGR cooler walls. If the engine coolant is near the boiling point of exhaust gasses - less condensation occurs. This leads to less deposits.

On the Gen 4 the deposition is reduced because the EGR is taken after the converter. The converter breaks down soot particles and hydrocarbons.

Pixel XL ?

 

"Perhaps"
Now, when you say "clogging", does this mean deposits in the EGR system (Like every car everywhere with EGR), or do you mean complete lack of flow through the EGR Cooler?

Exactly way the VAST majority of Prius owners operate their Prius. (You know most have never heard of PC...).
And what are ALL these owners experiencing when and if their EGR system gets partially or completely clogged?
Less fuel economy ?
Less Max power, when asked for it ?
Or the hypothetical 'early head gasket failure' ?

 

Yes, I have. you don't take criticism easy, do you?

 

I drove ours with ScanGauge connected for about the first 3 years, often saw coolant temps plateau only around 65~70C, especially in winter, even on extended drives.

 

that results in engine knocking under heavy load conditions. countless PC threads on this, if you search. Some assume such knocking damages the HG. I believe it because the corresponding 1.8L corolla engine has no HG problems.