EGR Maintenance

My take:

With third gen, Toyota engineers were under the gun, to come up with a more fuel efficient engine. They accomplished this, albeit with an engine that would run hot, counting on the new EGR system to both keep the temp down and reduce pollution.

It was their first crack at EGR, they didn't test it enough, give it enough cross-section area to flow, and they connected it upstream of the catalytic converter.

The EGR slow-but-sure clogged up, engine temperatures climbed, and that caused all sorts of bad things.

Fourth gen actually mentions "revised EGR" in some of the sales documentation, which seems strangely deep-dive.

My admittedly seat-of-pants view: if you've gone from a shiny-new EGR and intake manifold, to one that's near-completely socked-in with carbon, that can't be good.

It's a chicken-and-egg thing, hard to say for sure. I'll just keep on top of EGR (and intake manifold) cleaning, see how it goes. That's my lab test.

Only trouble: our usage of the car is like one of those drum solos, where the beat goes slower, and slower. At almost 87K now (been closing in on it for about 3 months, lol). I don't know if the car will ever get to 100K, in our hands. So far no drop in the oil level, between changes.

Those odometer values are in kilometers...

 

HI Mendel,
Nice try.
There is no evidence the the engine temps where higher than design.
Here's the kicker.
My 2016 engines, that's 2 of them, running on 2012 EGR's, coolers and intakes, have not burned any oil, have not needed to be cleaned and have run flawlessly for 30,000 and 40,000 miles.
I expect to go another 300,000 each without any major repairs, only scheduled maintenance.
Bad rings to good rings makes all the difference.

 

I agree, there's tacit admission in the attached.

Toyota:

"Got high oil consumption?"

"We'll do an oil consumption test, and if you fail (or is it pass?), we'll put in some different pistons and rings."

"What was wrong with the old pistons and rings you ask? Oh, don't worry about that."

"Wait a sec, you have over 60K miles? Go pound sand."

Funny thing: if you look up the 2015 Prius (the one year with the revised pistons/rings, for sure) mpg numbers on fuelly, they barely budge. That's another sand pounder.

Toyota Prius MPG - Actual MPG from 8,161 Toyota Prius owners

Something else with the above link: if you look at the number of fuelly registered vehicles, year-by-year: what the heck happened with 4th gen? Could be owners just aren't registering with fuelly, but it sure looks like the sales volume ran off a cliff, lol. Even with mpg a solid 10% better.

Still, I'm putting some of my money on the EGR, will just keep maintaining my test subject.

 

The "problem" was too-small return holes in the piston behind the oil ring. Designed around 0W-20 oil, Toyota didn't count on people being "frugal," and using 5W30, or whatever their pappy used to run, with extended intervals. Oil through the rings is also a cooling mechanism, and the higher kinematic viscosity oil brings compound problems to the table. First is that it doesn't flow through the small holes as well, leaving it in the rings longer. So it tends to coke. Less flow also cools the rings less efficiently, so it tends to coke. The rings end up bound in burned oil, and not able to seal against the cylinder wall, as well as the oil return holes completely closed off.

The new pistons have larger oil return holes.

We've been able to actually reverse oil burning when it's caught early by simply returning the car to a 0W-20 diet, and changed frequently. I've heard stories of well and properly maintained engines that start burning oil, but never seen one. The gen-2 and newer taxis we work on have unbelievable mileage on them, and zero problems, but they're all maintained by the book.

Knowing this, it's amazing to me that Toyota warranties it at all. GM will actually test the oil on early engine failures, and if it's not a certified oil (note that "meets or exceeds" is not "certified"), you'll be buying an engine.

 

I'm wondering if there's any data on early Gen 3's with high miles and no EGR circuit issues. On forums we tend to hear about failures more often than non-events. I don't think I would trust a hired mechanic to properly clean my EGR circuit. Definitely a DIY situation to make sure it's done thoroughly - but it looks like a job that would test my patience and skill level. If the alternative is a blown head gasket, then the decision is easy. What percentage of early Prius Gen 3's do you think are out there that never burned any oil, ran with fresh high quality synthetic oil changes every 5k, and quality fuel, and made it to 300k without an EGR circuit issue?

I can imagine pulling my EGR pipe and cooler, and spark plugs too, and finding them looking quite serviceable at 150k. Maybe it's a "pipe" dream......but Toyota's are funny like that.

 

probably a decent amount. we've had plenty of reports of no oil burning and no egr clogging. it's a lottery though

 

Nice new avatar.

A socially distanced pool, that you lost your hat in?

 

Dibs on zero.

 

There seems to be a fairly non-invasive way to get an idea how clogged yours might or might not be. It doesn't necessarily clue you in to imbalance caused by non-uniform clogging of the passages in the intake manifold, but then getting just the manifold off by itself for a look-see isn't much of a knucklebuster.

So, a lottery where you're allowed to peek, a little.

 

The v has the same problem.

 

Yes, unfortunately same engine/egr...so sad for this joke of an issue toyota turns the cold cheek to us

I just hit the big 33k on my 2015 liftback, so I am way behind @Mendel Leisk albeit younger model
I have no clue at what mileage I will do the check. I am antsy on checking manifold for oil.
But my oil changes come from time vrs distance. was at 1 yr, but I am now doing 9 months.

haha, but real question of this thread is the Prius 'C" well at least that was what OP was asking. No issue there!

What is nice about this thread is that we have 3 or more "causes" that are different and they
all sound like good guesses.

Still leaves my 15 with the updated pistons and rings sitting on the sidelines just watching the grass grow lol

 

I've been wondering the same thing.

 

Howdy, my first post. Greetings from Finland Just bought a 2010 Prius with 210kkm in the clock (130kmiles). Taking it to official Toyota service in two weeks since last time it was there seems to have happened 80kkm ago (2017). Engine oils seems to have been changed promptly, though. Anyway, at the service they said car is missing sw updates (”engine/HSD”) so they’ll update sw and replace all fluids&oils including transaxel, filters, spark plugs. Inverted coolant change needed in 240kkm so they did not recommend. Budget was very reasonable in my eyes. This wide maintenace for my Volvo would have cost lot lot more.

Anyway, just wondering that could the sw update relate to egr by any chance? And isn’t clogged intake manifold bad for mpg? I hear turbodiesels are more tolerant by nature. Saw a picture of diesel Toyota manifold that was so clogged that one could barely stick little finger there. That car had just exhausted in the highway and needed to be towed to shop.

Reason why i’m interested in egr is the engine wash(flush) that previous owner had had done during last oil change. There may have been oil consumption issues or not, lets see. During first 1000km i have not noticed anything dramatic

 

The software is supposed to be updated every time it's at toyota.......

 

It Is??

Am I forgetting or missing some software updates not connected to a recall notice or a TSB?

Or is Toyota being confused with Tesla?

 

You stated it had good records. Was the oil changed at toy?
Pretty hard to confuse a prius with a Tesla.....

 

If a software update is part of a recall, you're not supposed to have to ask for it, and it's free.

There can be software updates announced in TSBs, and you might ask to have those installed if you are having the issue described in the TSB. In those cases you might pay for around an hour of shop time to install the update.

Some updates are paired with hardware changes. There is a software update related to EGR that should be installed if and when you change to the different EGR valve that was announced in the same TSB.

 

Checked from local Toyota webpage and it appears there is a valid recall for this particular VIN. ”Hybrid system control unit software update” and it’s naturally free of charge. Previous owner had not bothered.. I assume their system does check whether car has been to shop for this or not. This was only one system reported for this VIN.

 

This car has not been to Toyota shop since 2017 autumn. Serviced at some independent shops (oil changes).

 

It has a PCV valve that is positioned in a much less problematic place - ie top left of the valve-cover. It also has an inline secondary heat-exchanger to keep the gasses at engine running temp. (A tube running down the right-hand side of the block)