Please help me diagnose this

Leaking into cylinder can lead to bent piston arm, since the coolant won't compress. I would confirm coolant in cylinder (with boroscope and/or leakdown test) and get on it soon.

 

Clogged EGR and intake is likely cause: makes engine run hotter.

 

Is there some go-to thread on this topic on PriusChat, the one that says how much hotter, measured by what methods, published where?

I know it's reposted like everywhere, I just haven't found the place that looks like anything besides a reposting yet.

 

I don't think so. But it's accepted lore that introducing exhaust gas displaces oxygen, reduces combustion temps?

Just googling, a quote:

When the air/fuel mixture in an engine is burnt at a very high temperature, greenhouse gases such as nitrous oxide tend to be produced. By reducing the combustion temperatures through the use of the EGR valve, this is reduced dramatically without having a significant impact on the efficiency of the truck. In the end, the presence of the EGR makes your truck more environmentally friendly.

Found here:

How Do You Identify Problems Associated With The EGR Valve? | Pacbrake

And this:

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide emissions reduction technique used in petrol/gasoline and diesel engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures.

At the outset of the wiki article:

Exhaust gas recirculation - Wikipedia

 

Right, but again, my question was about the quantification, and the strength of support for linking it to HG failure. I'm not even being skeptical, merely curious. The necessary work may have been done, and there may be someone who knows where or by whom and can cite it. I don't mean my curiosity to come across as a challenge to anyone who doesn't, but just to open a door for someone who does to respond.

 

One hope: keeping on top of the EGR cleaning, will that keep the blown head gasket "wolf" at bay? Stay tuned...

 

Have they diagnosed head gasket failure, done a leak-down test, or just going with the codes? That's very likely the issue, but still...

At least run a boroscope in through the spark plug holes, look for coolant?

Both those quotes are reasonable, but I'd assume both would be the bare-bones approach.

For example with the head gasket that's the only gasket they'd replace, and that wouldn't include a machine shop going over the head, replacing valve seals, cleaning/checking.

And the engine swap a salvage, likely with more miles than yours. And would they pre-emptively do the head gasket on that one, or at least leak-down test it?

But maybe that's ok, in particular the head gasket route, get's you on the road, and finger's crossed good for another 100K.

Do completely clean the EGR circuit and intake manifold. And look into oil catch can.

 

Yeah they exist. Our 2010 currently has 86,000 kms, roughly 54K miles.

Good luck with your repairs. Again, I think it's the clogged EGR that's killing head gaskets, just have to keep on it.

 

Theres no proof that the miles on the engine are really 97K miles or not. They can slap an arbitrary mileage driven sticker and it doesn’t have to be true. Bring the devil advocate reading from others experience

 

Yeah leak-down test is not really something owners normally need do. A shop that's advocating head gasket repair should also have the competence to do leak-down. It takes a particular set of gauges and some know-how, but it's not that involved. Or at least boroscope inspection, look for coolant atop the pistons.

I get the sense he went in, said "I think my head gasket's bad", and they responded "we can fix that".

Ultimately, it'll hopefully work out, but it's a little sketchy...

 

Cha-Ching for them

 

Yeah, I bought a used Engine with 90 something thousand miles on it (yeah right) I showed up with a bad head gasket.
Just Bought a 2012 For $700 with a Blown Head Gasket | PriusChat

 

For that reason alone, the head gasket only repair might be better option. A new engine is a new variable.