2010-2012 Head Gasket failure analysis

Just to clarify: by “oil breakdown “ would you mean a loss of viscosity, an exhaustion of the anti-wear additives, or both? I ask because I would think that a really thorough User Oil Analysis could fairly easily check for the viscosity breakdown, but probably not for the amount of anti-wear additives as I understand that each oil brand may use a different mix of those. Possibly you could have some kind of resistance-to-abrasion test done, but unsure if any UOA firm does that. My understanding was that the fully-synthetic oils were more resistant to viscosity breakdown than the older, multi-weight traditional ICE oils, but 10,000 is a long interval.

 

Two things why I don’t think your theory is valid:
- In Europe Toyotas have ~9k miles (15k km) service intervall since about 2000 - including second generation Prius. (VW group has 18k miles [30k km] service intervall, but that cause quite some issues and require special oil.)
- Some VVTi engines - 1ZZ and 3ZZ - have started consuming oil when 10W-40 oil was used instead of the recommended 5W-30.
- Very similar issue with the 1.33 engine - sorry, I don’t know the engine code - when using 5W-30 instead of 0W-20.

 

Apples vs oranges, those are different engines compared to Prius.

 

It’a very similar that Toyota recommended more viscosous oil and not using the recommended caused problem for the engine.

 

Thanks for the thorough investigation. My 2012 Prius II was just in to the dealer for an engine light. The car had been bought new and dealer maintained (every 5k miles). The diagnosis: blown head gasket, with coolant leaking into 2 cylinders. The dealership wanted me to replace the engine ($6500). A trip to a second shop indicated that one cylinder was misfiring, very limited. Conclusion, perhaps a small leak in the head gasket, but car could still be driven, perhaps for a while. I contacted Toyota customer service and they denied all blame for faulty head gaskets. I also filed a complaint with the NHTSA. My advice, if you have a 2012 Prius, trade it in now. If you're looking for a used Prius, avoid the 2012 models.

 

Honestly I think it is all the Gen3's. The older they get, the more likely this is to happen...especially if the EGR circuit hasn't been cleaned.

Ironically, my daughter has our 2010 and just reported the dreaded engine knock...which seems to be an indication that the EGR circuit is partially/fully plugged. The theory is that this later leads to head gasket failure. I better get my butt in gear and get that EGR cleaned!

 

^ What he said.

Again: how many miles, and on which cylinders did the failure occur?

 

Now is as good a time as any to do it.

What other activities you got going on?

 

There is nothing wrong with the 3rd Generation Prius head gasket.
The EGR system IS a weak link. Now, most people know that. Someone who doesn't know anything
about the Prius, doesn't. But, if they did some research, they would. It's really a minor problem.
If the system is cleaned, most importantly, the cooler, there really is no reason for the head gasket to
fail any sooner than any other car.
I bought my 2010 Prius in July 2017 with 116,xxx miles on it.
In June 2018, with 138,745 miles on it, I cleaned the egr system and intake manifold.
The manifold with oily and the egr holes were only slightly blocked. The egr valve wasn't bad, and
the cooler was sooty, but mostly clean. Easily cleaned with oven cleaner and hose.
Monday the 23rd of March of this year at 199,932 miles, I did it again. The manifold was very oily, and the egr
holes were about 1/3 blocked. A brass bore brush in a drill and gunk clean that up!
The egr valve was very sooty, but easily cleaned with a brass brush and brake cleaner.
The cooler on the other hand, was almost completely blocked. I could see a little light through it.
I was VERY glad I have purchased a spare cooler! And that one was in the same shape as mine was when I
first cleaned it.
This time I used a pressure washer to clear it out as suggested by Raytheeagle(correct me if I'm wrong). It did
clean it out. But Sunday, I decided to use the oven cleaner just to see just how clean it was. Even though it was clear,
nasty black stuff came out. I cleaned it 3 times and rinsed with just a hose before it was clear.
The difference between the first 138,745 miles and the only 61,187 miles was I drive a lot more at 70mph, and faster
in town then the first time.
As with any car, the harder you drive it, the more it wears. I burned a quart and a half of oil this past oil change when I
normally only use about 1/2 to 3/4.
So it's back to 65mph for me!

 

This is interesting because it seems to indicate that the EGR system was reasonably functional until around 125K(?), but sometime in the last 60-75K it was unable to keep up with the amount of oil the engine was consuming. Some questions: what is your oil change interval, what weight oil are you using, and did you install an oil catch can? If you are using an OCC, did you notice the quantity of oil/water/etc captured increased over the last 50K? Thanks in advance.

 

The man I purchased it from was the original owner. He had EVERY record of maintainence!
He drove 65mph or less. He was easy on the car. So was I. The first time I cleaned it.
But, I was behind in time, and drove faster. Got tired of jerks on the road and just wanted to get
off the road as fast as possible. My fuel milage dropped too of course.
I was using about 1, maybe 1.5 quarts of oil between 10,000 mile oil changes. 0w-20 oil for most of it.
The last two oil changed have been 0w30. I really haven't notice any difference between them.
No OCC. The one I bought won't fit! It's too tall. Maybe next time.
I've been driving 65mph, and easy in the city. So far the oil level is only down a little on the stick.
I did replace the pcv valve this time. Last time I just cleaned it. I think I will change it each time
since it just cost $9. I believe the spring gets weak so cleaning it with carb cleaner doesn't help.

I believe, like any car, if you drive the Pruis, like a Prius, and not a Formula 1 car, you'll use less oil,
and less clogging of the egr cooler.
Coolant levels have not changed when I've changed them. I've had to ad a little after driving a normal
day's drive and letting it sit overnight. Which is more or less normal with any car.

 

Thanks for your reply ASRDogman.

Interesting that you changed your PCV valve and have noticed oil usage was reduced. I've read numerous other posting where other Gen 3's started noticing around the 100K miles that their Gen 3 oil usage went up, usually at fast highway speeds. Gasket Masters mentioned in their YouTube video that replacing (vs cleaning) the PCV valve usually cured oil burning in high mileage Gen 3 Pruis', and especially in those used in taxi fleets. Many YouTube viewer comments seem to confirm their statement. So could a stuck or worn/weak spring in PCV valve be the initial cause for oil burning, which then leads to a clogged EGR system, high combustion temps, engine knock and blown head gaskets?

 

I did not change the pcv valve the first time, just cleaned it. I did change it the 2nd time.
I "might" have helped to reduce oil burning, but driving 65mph versus 70-75mph, and driving
more economically in the city is what reduced it the most.
The Prius is (was) designed for fuel economy, not racing. If you drive it like that, it will give you
great mpg and use less oil. That is why I got it.
My Town and County van, with 375,000+ miles on it, was getting 16mpg in the city, and 22-25mpg
on the highway, driving 60mph. And use about 2 quarts of oil during 7-8000 mile oil changes.
I use 1-1.5qts every 10,000 mile oil changes.
I average 37mpg in the city and 44-49mpg on the highway driving 65mph. I'm very happy!

 

My 2012 v 135K miles is in the shop right now... for everything mentioned above: cold start hard shakes for nearly 10 seconds then smooth idle but no smoke that I noticed but in the last couple of days it was getting worse and worse...I called it in and took it to the shop. Still waiting for diagnosis but I wouldn’t be surprised if this is the culprit...

 

I just bought a 2012 Prius v at 186k and this imminent engine failure is giving me a lot of anxiety. It was a clean title, original owner, with good maintenance history. No lights no codes.

Is it worthwhile to change the head gasket to the most recent part number before anything bad happens or can that cause more issues and require machining. Is there any other maintenance I can do to try and prevent these engine issues?

Right now I about to change my transmission fluid and maybe the coils and spark plugs. Besides that, I do regular maintenance like changing air filters and oil. I hear it's good to clean the EGR regularly and add an oil catch can on these. I'm hoping there is something else I can do to avoid an engine rebuild or replacement.

 

If there’s currently no signs of head gasket failure I’d get on Exhaust Gas Recirculation and intake manifold cleaning ASAP. More info:

Bad Flywheel | PriusChat

 

I spoke to the dealer tech about this and he said it is a common misconception the the head gasket issue is caused by the EGR when it is not. He mentioned the real reason is that the coolant water pump. Especially the early ones. They variable E pump starts to fail and does not work correctly and that causes the hot spots. Anyone heard of this? He said to replace the pump at every 100k miles and not get the Asian brand because they are fakes get the OEM from the dealer.

 

IIRC, The Car Care Nut talked about it similarly in one of his Youtube videos. He attributed it to coolant issue (either corrosion or water pump failure).

 

How early? Are pumps sold by dealers now more durable than my 2011 one?

 

And the 4th gen pumps are miraculous…