Is Head Gasket failure common in Gen 3?

Actually sealants will identify an early or intermediate head gasket failure with some level of certainty. Generally clears symptoms for several months before the rattling comes back. But the wrong products, excessive quantities or shortcuts with the better old school sealers will certainly clog radiators and heaters and will likely allow the engine to degenerate enough where replacement is required.

By the way, its bad form to respond to old threads where the original issue is history.

 

You may be thinking of the old school sealants. These new ones are silica based and require a procedure to get them working.
I have a bud that puts outrageous miles on a fleet of Gen 2 and Gen 3 Prii. Any amount of miles you work with, add a zero or two and that's his usage.
He's had good luck using Blue Devil in his Gen 3's and it has allowed him to defer head gasket replacement by ? 50k miles or more after the first symptom.
And he now prefers Gen 2's because of the history of head gasket failures in the Gen 3. Last time he needed a replacement Prius I tried to talk him into a Gen 4, but the not knowing if there is a change in the head gasket system, he went with an old Gen 2.

So, back on topic !
Is it common to have the head gasket fail on a Gen 3 when in the +200k miles?

 

old thread, new life.

I was actually looking for the most recent active thread on this subject rather than to start another going over ground that has been covered in many threads. it is still possible with 7 pages that I missed answers to the questions I asked so it's always a question of style and efficiency whether particular aspects of this general topic deserve a well titled thread of their own. glad to follow it where-ever it goes. or if there are pointers to other threads for the specifics i'm asking.

appreciate the patient recitation by @Mendel Leisk of the relation between EGR clogging and head gasket failure.

only recently i found him talking about some techstream addressable sensor or code for EGR flow (maybe insufficient EGR flow P0401) . can anyone elaborate? my concern from another thread where this is mentioned is that the EGR was quite occluded to all appearances and yet it hadn't thrown the code yet. e.g

Will some other generic OBD devices with prius parameters interrogate for that code. I assume it shows a check engine/code light when it occurs? But it seems to me not that usefully prophylactic if you can get really gummed up before it throws the code? Can one interrogate the sensor to check flow short of the low flow code or is it simply a threshold sensor?

I did find one gentlemen who has seen quite a few of these Gen 3s in taxi usage who swears by every 10th tank run premium and do a partial tank Lucas additive treatment after than and before every third or 4th oil change run Rislone Engine [oil] Treatment for 40 or 50 hours with an intent to reduce EGR fouling amongst other engine problems.

Not sure if careful chemistry and cleaning on the go is really a substitute for removal and cleaning or extend time between cleanings?

And there seems to be some reference to changed cooler design for latter half of gen 4. Don't know if one knows by model year or when exactly the change came in and again, whether this is a significant improvement that extends service interval or with active cleaning from premium gas and additives might obviate the need.

I notice that folks will sometimes buy a used cooler (and valve?) and clean those to have a replacement ready to go. I take it there is no aftermarket version and to simply get a new one to start clean from toyota would require a second mortgage?

Thanks,
brian

PS In the inquiring minds department: there is another long thread about whether any of this is toyota's problem ( How do we get Toyota to recall Gen 3 Priuses with head gaskets issues? | PriusChat ). my main grief with toyota is what kind of maintenance bulletins and recommendations are out there short of the P0401 code. By the time you get that code, operation could already have compromised the head gasket as least from anecdotal reports. Would it make sense to reprogram the set point for that code. Or should there be active preventative maintenance cycle without the appearance of the code, whether those recommendations are for active chemical treament, physical removal and cleaning or checking the flow parameter at some interval. It certainly isn't a safety flaw that one anticipates the FHSA worrying about and more a customer satisfaction issue. surely, if it weren't for government regs they wouldn't have these complications on there. I'm not a whacko on this stuff but presuming (i'm not an emission engineer) that there are craploads more of the black sooty particulate that actually does get burned through recirc maybe it is justified). I am a little perplexed as to the extent to the extent of exhaust gas recycled, if it doesn't all go back through how clean can it be but obviously you can't continously recycle 100% of exhause or anything like that. Is there some centrifugal or other filtering design component that tends to channel particulates through the EGR vs. the bulk of exhaust gas? Is the EGR valve itself only operated or operated at signifcantly large recirc rate at times of cold operation or other challenging emissions parameters?

and one presumes that while this site is devoted to Prius so we read about this problem in relation to Prius I'm assuming that this technology leads to problems in other vehicles from toyota and other manufacturers. Although maybe there are designs that are less constrained than in this circumstance that aren't reputed to give as much trouble.

 

Toyota and the rest of the world outside of Priuschat do not see an egr hg cause and effect. A clogged egr will eventually code; Toyota mechanics simply replace the parts.

 

So what about archi's picture above? That is CLOGGED.

And without EGR working properly, are we thinking combustion pressures are getting so high that the head gasket fails?
Is detonation not part of this equation? Detonation should be stopped by the knock sensor.

As for getting toyota to care about cars in the +200k mile range,,, good luck.

 

For practical purposes, you can pretty much take it to the bank that a full cleaning every 100K miles, at the least, is warranted. They all seem to carbon-clog, quite reliably. If you want to know how it's progressing, removing just the stainless steel pipe between EGR valve and intake manifold is quite easy. @NutzAboutBolts has several good videos on the subject. There's links in a thread pinned at top of 3rd gen maintenance forum.

Haven't heard of that. Toyota appears to have "solved" the EGR clogging, right from the outset of gen 4. The cooler cross-section area looks to be roughly doubled, and the gas is (as of gen 4) being taken from downstream of the catalytic converter.

The price of used EGR components has jumped, presumably with demand. You can just clean it all, if you don't mind a day or three down time. A new EGR cooler is currently showing as $177 CDN for me, plus $35 shipping, from Japan:

Exhaust gas recirculation system for Toyota Prius XW30, 3 generation 01.2009 - 11.2011 - Toyota Car and Auto Spare Parts - Genuine Online Car Parts Catalogue - Amayama

Buy Genuine Toyota 2560137010 (25601-37010) Pipe Sub-Assy, Egr W/cooler. Prices, fast shipping, photos, weight - Amayama

For owners, yes. For Toyota, maybe not so much...

 

The P0401 code is thrown in response to a certain self test that the car periodically conducts; when the result goes below the allowable minimum, the P0401 code is thrown. It is easy to query for the latest test result value, so you can see how it is trending; you do not have to wait blindly for it to cross the alarm threshold and set the code. Techstream is not required; any scan tool that can do "mode 6" monitor result queries can show you the test result.

I don't know whether the image above is archibald's own or was copied from another thread. Clearly, it would be of great interest to know what the flow test value was just before that image was taken, and the mileage.

Test values slightly above 20 kPa seem to be typical of new or just-cleaned systems. Mine was 10 point something just before I cleaned it, around 15x,000 miles, and 21 point something after. The result is given in pressure units (kPa) because of the way it is measured: there is a pressure sensor in the manifold, and it is used to measure how much the pressure changes due to EGR flow when the valve opens.

For comparison to the image above, mine at that point when I cleaned it had an open passage with a layer of carbon on the walls, maybe the thickness of paper.

What's being shown as we collect data is that clogging proceeds at different rates in different cars. Expecting them all to be clogged within 100k miles does not seem consistent with the data so far. The more data we get (ideally with mileage attached), the more we can say.

A complication in this storyline is that the cross-section area is increased because the gas is taken from downstream of the converter: the pressure downstream there is lower, requiring all the plumbing to have its cross-section increased simply to keep the same flow properties. That's covered in the literature on "catalyzed EGR", which was a subject of industry-wide research during the Gen 3 years and was adopted for Gen 4 after a bunch of study of the different chemical composition of the gas downstream and its effects on combustion. The story does not seem to easily simplify into a morality tale about Toyota doing it wrong and then doing it right.

 

Still, going from chockablock carbon to minor soot is an improvement?

 

I have 263,351 miles, as of today.
Original head gasket, water pump, inverter pump....
Cleaned the EGR system twice. Shortly to be 3 times.......

1st time the cooler wasn't super bad, as I've seem some on here.
2nd time its was not quite as bad.

Averaging around 46mpg for the cooler weather...

 

you are an old hand priuschatter. but can't quite tell what side you come down on?

 

i follow your point that significantly reduced carbon build up is a solution. And if there are operational complications to post cat uptake i'm not clear what they are yet @ChapmanF .

This might be a good reason to get the popcorn for your earlier invitation to watch a gen 4 engine swapped into a gen 3 car. not sure if that means you need the cat and whether that would normally come with the engine or how the different cooler pathway is dealt with . . . maybe that's in the video that will have to wait til I have that binge time.

thanks all for attention to these questions.

brian

PS while some cars seem to build up more than others, does anyone think there is merit to the periodic crossover to premium gas and to periodic use of additives?

 

It's simply that pre-cat and post-cat EGR are two distinct approaches to engine design. The catalytic converter does two things: (1) it is a flow restriction, so the post-cat pressure is lower than the pre-cat pressure, and (2) it chemically changes the composition of the exhaust.

Because of (1), the size of the EGR plumbing has to be specified accordingly. The cooler and valve have to be larger for a post-cat system, or will not deliver enough EGR because of the lower pressure. Conversely, if you put the larger Gen 4 EGR plumbing into a Gen 3 fed from the higher pre-cat pressure, it will flow too much EGR, which has been exactly the experience in many reports of Gen 4 to Gen 3 engine swaps here when someone tried to use the Gen 4 EGR plumbing with the Gen 3 exhaust.

(I have not seen a project yet where someone tried to transplant the Gen 4 exhaust also, in order to get the lower-pressure gas after the converter. That project seems to have how-to-make-it-fit complications.)

Because of (2), which design is used changes which chemical reactions happen in the cylinder when the EGR is used, and those differences are taken into account designing the engine and the control strategies in the ECM. I'm not a chemist and if you're interested in that part of the picture, you should probably skip me and read the papers on catalyzed EGR.

 

He retains third gen EGR components. It's support points are all lost, so the system free-spans, from exhaust to intake connections. Seems fine.

 

At least you have the tools

 

Use a pressure washer for the cleaning and you'll be within the repair window and not extend it out.

15 minutes per cooler is about right.

But tackling the egr circuit is a very prudent move.

 

That's awesome. I had a class (partly) on Kohlberg's moral development model....

 

not sure the point. well OK lower miles and maybe greater availability since Gen 3 engines are getting snapped up to replace those with blown head gaskets.

Here's the guy who did it with the 4th gen EGR.

If cleaning the EGR really heads this off even in high mile cars with no symptoms yet, maybe my worry about engine swap is overdone. The cleaning seems perfectly well addressable but I can see that there is a degree of avoidance of gen 3 now that this problem is apparent, and especially because toyota seems to be strong arming it. (I'm not saying it is their responsibility to fix, I feel like they should do better in terms of advising prophylactic service, resetting the trigger for the EGR low flow code, or god forbid reprogramming onboard electronics to read out coolant temp in the corner of the onboard screen.etc.) as @rjparker has suggested, they don't seem to think–or admit– head gasket failure is associated with EGR clogging. If not what is it associated with? just a poor design of the engine or everybody who has this problem has had some kind of other coolant loss/failure they aren't aware of or disclosing? Agree with you (I think it was you) that added to the list of recipes for disaster lack of a coolant sensor. Is there any coolant temp monitor available in the vehicle section of the onboard electronics or is there one that can be plugged into the OBD?

 

Gen4 engines are far superior and have a stellar record since 2016. New cylinder cooling ports, insulators, intake, egr, improved cylinder tumble ratio, active grille shutters; the list goes on and on. Gen3 lasted five years and was a known problem on many fronts three years in. Gen4 is six years in and its engineering has been ported over to most vehicles in the Toyota and Lexus line.

I use an obd2 temperature monitor and alarm. However the gen3 cooling system in general is good and well monitored by the factory system. Owners who continue to drive after a temperature warning get a warped aluminum engine and a normal hg failure.

P10 obd2 Display

 

The 2015 or newer Prius has way less problems including head gasket. Yet, the 2010 with the highest head gasket problems still much better than any problematic european cars, Crysler, GM that barely can reach 100k miles.
Yes the number is high but statistically way more people I know has no issue. People with problems will always post and curse, I know how angry I was with my Altima 2002 too.

 

2010 Toyota Prius | CarComplaints.com
Reflect enough statistics that 2010 could be very problematic if it is not maintained properly. Head gasket after 150k miles is kind of bad for Toyota standard, but 100k miles is a dream for Fiat