Another 3 gen head gasket

What kind of miles are they at? How do the EGR systems and intake manifolds look?

What are you, an independent shop, freelancer?

 

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.

 

Good info for others........ I personally think the cars are poorly designed.

 

Hey Tim (or others),
I've been thinking a lot about getting a Prius and have looked around 2010-2013s... haven't even driven one yet... Do you think these are good cars in other years perhaps? Should I shy away or look into certain year ranges?

 

Pistons and rings were revised somewhere through model year 2014. Maybe someone could track down a VIN range, not sure. 2015 for sure will have the revised pistons/rings. Object of the revision was apparently to reduce oil consumption (see attached ...169, it shows the new piston/ring part numbers, and an interesting read).

FWIW, there are some earlier years still with little or no consumption. Maybe lower miles in particular? Cleaning the intake and Exhaust Gas Recirculation might help as well. Shorter oil change interval might help also, say 5000 miles or 6 months, whichever comes first.

A survey, year vs oil consumption:

3rd gen model year and oil consumption | PriusChat

 

Should I Change The Engine Or Head Gasket On My 2010 Prius? | Torque News

 

From the article:

"The EGR cooler and system can get plugged up with carbon deposits. When this happens, you will get a P0401 EGR Insufficient flow code, and your Prius will not function as designed. The other thing that happens is you are not allowing full pressure to be released from the engine.

Not allowing full pressure release from the engine can cause unnecessary back pressure and overtime contribute to the head gasket weakening and eventually lead to coolant consumption. This process does not happen quickly, which is why many owners will not notice the problem until it is too late."

He's saying "back pressure", by this he means exhaust back pressure? On my first read, I got the impression he was talking about the kind of back pressure you'd get with a clogging PCV valve.

I think exhaust back pressure is more likely to be caused by a clogged Cat? Not really knowledgable, but I suspect the EGR flow is not that much, even with brand-new, fully clean system.

I definitely think the EGR is connected to head gasket failure, but my take it's due to an ensuing rise in combustion chamber temps (which the article doesn't mention): EGR flow keeps those temps down. Someone may be along shortly to say in the absence of testing I shouldn't speculate about this.

 

Yes, here I am.

It's weird, because you totally noticed that an article was saying (flat-out saying, like something established), yada yada back pressure release yada yada, and it totally triggered the correct reaction in you, namely: hold on a sec, by how much are you saying EGR flow affects back pressure, and how big an effect on back pressure would be needed to damage the head gasket?

And then you move right on to the "EGR flow keeps those temps down" business, which is simply begging for the exact same reaction: hold on a sec, by how much are you saying EGR flow keeps those temps down, and how big an effect on chamber temps would be needed to damage the head gasket?

It's not that either proposition lacks truthiness. It stands to reason that EGR flow lowers back pressure to some extent, and that it lowers peak combustion temps by enough to reduce formation of NOx, because that's what it's there for. We just don't know if either effect is in the ballpark of enough to explain HG damage, or twice that strong, or half that strong, or ten times, or a tenth, or a hundredth. That's what both propositions are suffering from, in exactly the same way.

As far as the temps go, I'm actually not saying "in the absence of testing ..." because the necessary questions (like "how much combustion temp difference does cooled EGR make? how much difference does carbon in the cooler make? what are typical temp limits for head gasket materials?") probably all have answers that can be looked up. Testing would only be needed as a way to escape the dire fate of entering a library.

 

2 Ways To Avoid $6,000 In Repairs On Your Toyota Prius | Torque News