What is the chief cause of head gasket failure on the gen 3

Does anyone think thinner 0W-20 oil contributes to this? Thinner means easier to escape with blowby even with improved engine tolerances.

Of course having oily blowby filtered out to keep intake clean is good practice. Lots of engines can do this without a catch can. Is gen3 Prius's blowby oil trapping mechanism particularly bad?

 

Look through the throttle and you'll see a pool at the bottom of the intake manifold, and who knows how much just passes through.

 

Didn't somebody have a theory that it was the position of the PCV valve or EGR ? There were changes in EGR for Gen 4 so we wonder if that has helped with the issue. It is too early to tell.
An oil catch can, regularly emptied, seems to help a lot with the issue.

 

Yeah seen that in my prior TB cleaning effort which suggest a fairly poor blowby oil filtering design.

Every design I've seen before (a couple of turbo engines which has really complex PCV designs due to losing intake vacuum when boosting) uses baffles to concentrate the oil from the blowby vapor and gravity drip+drain it back to the block/pan. Haven't pulled IM yet on this engine but I think there is a hose that goes to the block which would be the filtered oil drain return. If this isn't located at the lowest spot, then can't remove all the filtered oil, hence, catch can is the only remaining solution.

 

There is a bit of a labyrinth in the engine block, right where PCV valve screws on. It's behind a bolted on plate, maybe 6" square. Drains a little back. Not really effective though.

 

If it's "not really effective," how can normal oil consumption (i.e., before becoming a heavy drinker) be so extremely low overall? So far, mine seems to manage better than 30,000 km/liter (by extrapolation, NOT direct test!).

 

I guess from what accumulates just below the throttle body, and/or in an oil catch can.

 

Specualtion: Excessive blow-by can force more oil out the PCV valve. It seems that the updated piston and rings in 2014/2015 might have been to help with blow-by. More speculation, by having more oil fed back if not caught by a catch can, there's more carbon buildup in the combustion chamber, which might prevent the rings from sealing properly, further increasing the blow-by. The more oil you suck into the intake to be burned, the more oil consumption you will have. If you haven't reached stage 2 blow-by, then maybe it's only a little oil burn, slowly building up carbon as the miles go on, then when you hit the right carbon level so the rings don't seal, the heavy consumption starts.

 

how about this possibility. prolonged driving at the HSI settings just over the mid point to the right when ICE is in low RPM/high load regimen (about 2000RPM). when i do that, usually cruising about 50MPH, the ICE clearly works hard and you can feel some vibrations, that otherwise go away when one goes to the right end of ECO zone (about 3000RPM). maybe that stresses the HG, especially when the EGR cooler is not pristine.

 

My 2011 Prus had a broke haed gasket at 167k miles.. As diagnosed by the dealer. I took my car to Hybrid 911 in Garden Grove California and had my engine rebuilt. Since then have put 30k plus miles on the vehicle..

If I understand this article correctly , oly the 2010, 2011 and 2012 have issues?

 

So far, but we’ve seen some 13’s and 14’s suffering a similar fate.

Mind sharing details on your experience .

Thanks in advance for anything you’re willing to share.

 

I'm curious about how much it cost and how long it took. Also, what made you choose having it rebuilt versus having a different engine installed?

 

What about 2015? Did anything get changed for 2015 that is supposed to have fixed -- or at least mitigated -- the problem? Ours was built in June 2015 -- late in the model year; could it even have changes that became standard in the Gen4 cars?

 

In 2014 model year the pistons were revised, and in 2015 the piston rings as well. I suspect these measures were only to reduce oil consumption. I put this summary of part numbers based on info at McGeorge Toyota Parts website:



It's debatable, and I'm really not the knowledgeable, but I suspect the regular 3rd gen head gasket failures are due to clogged Exhaust Gas Recirculation system, and that's the same for all the model years, as far as I know.

 

They changed the rings and piston design.

@Mendel Leisk has the details with part numbers in an excel spreadsheet usually at his fingertips .

But those help with oil consumption of nothing else .

 

Looks like I’m slow on the draw today.

 

I thought you were supplying the Coles Notes version, lol. My pre-coffee rambles can be near-illegible.

 

Is Cole what Cliff is below the 49th parallel ?

 

Cole notes came out in '48. Cliff's came out in '58.

Pixel XL ?

 

You are going to see a certain number of failures for any major component for any car. The question is, "Are the numbers significant?" That's my question. What is the rate of failure over what period? And what was the cause and mechanism of the failures? Did the car overheat? Was the cooling system maintained and serviced? Was the proper coolant used?

There are so many things that can cause an individual failure. Let's get some stats, not just anecdotes.