Your opinions on 2012 engine failure

i haven't had any luck either. i think the problem is that it is not mentioned in the title

 

It's debatable, but my 2 cents:

Coolant got into the cylinders because the head gasket failed.

The head gasket failed because of elevated combustion chamber temperatures over a protracted time.

The elevated combustion chambers were due to clogged Exhaust Gas Recirculation system. The latter is instrumental in keeping the combustion chambers lower. The EGR system is a new design for gen 3, and woefully inadequate, prone to inexorable clogging.

The clogging of the EGR circuit may also have been accelerated by the propensitiy of the Positive Crankcase Ventilation system to dump an oil/water/gas oleo into the intake manifold.

Solution:

Clean the full EGR circuit, the intake manifold, reclean after another 50K miles, and set a service for future cleaning based on how much fresh carbon has accumulated.

Also: install and an oil catch can. Monitor it more frequently at first till you get a feel for how fast it fills.

The simplest way to see where you're at with the EGR, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Some tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough (or 1/2 plus reducer)
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

 

I think your best bet with the EGR is to read up, watch the videos, and then DIY. It's hopeless, and very expensive too, to get "pros" to properly resolve the issues.

More'n likely nothing needs replacement; thorough/complete cleaning is all that's required.

 

You don't need to replaced the valves

 

I'm suspect of the coolant/hydrolock theory. I don't see how it would even be possible for an engine to hydrolock while running at highway speeds.
Here's my rationale -- please correct me if my logic is flawed.
Say the engine is spinning at 3500 rpm. That's 58.3 revs per second. Because this is a 4 stroke engine, half of those will be compression strokes, so that's 29 compression strokes per second. I wouldn't think a fire hose could introduce enough fluid to hydrock the engine in 1/29th of a second.
Additionally, 200 degree coolant endering a 700 degree combustion chamber is not going to remain a liquid for very long.
I think the tech who did the engine swap is probably right: the engine ran low on oil, and self-destructed.
Or so it seems to me.

 

The combustion chamber volume is only about 55 cubic cm, or 1.85 oz. it wouldn’t take much coolant at all to fill the combustion chamber.

A slow leak from head gasket would burn off, but a sudden failure of it would overwhelm the cylinder quickly.

 

you will have issues......sooner or later.............

 

Something jumped the rails on that? The engine overall displacement is (admittedly nominally) 1.8 liter, or 1800 cubic centimeters. 1/4 of that is 360 cc, which is about a cup and a half, about 12 oz.

 

Well, the 1.8 l, or 360 cc per cylinder, is the displacement. Most of that gets displaced as the piston moves to the top of its stroke, leaving only the combustion chamber volume.

 

Good point. I wonder if you could determine remaining volume at TDC from the compression ratio, but I think there's something tricky about that ratio? Maybe due to valves remaining open longer than usual?


Maybe that's the volume @cnc97 was meaning?

 

Yes, the actual chamber volume is very small. For a frame of reference, a 350 Chevy typically has a 63 to 65 cc chamber volume in the head. And the piston is flat, so there is very little room to compress liquid as the piston travels up to TDC.

 

Thanks for the reply -- I didn't know it was that little. But I still don't think it's possible to hydrolock at highway speed.

Again, assuming 3500 RPM.
1.8 oz per stroke, 29 compression strokes per second, that's 52.2 oz per second -- for one cylinder. x 4 cylinders = 208.8 oz.

So 6 quarts per second still wouldn't be enough to hydrolock the engine. And at that rate, the engine would be out of coolant in 1.5 seconds. I just don't see a scenario where coolant could vacate the engine at that rate.

 

The bent/broken connecting rod and broken piston from my failed engine would beg to differ with you.

 

All it takes is one stroke, with more coolant in the cylinder than the minimum volume with the piston at TDC, and everything tight, valves sealed and so on.

 

Good point.

And a failure would likely be in just one cylinder anyway, so the other three aren't really a factor.

 

So just had the 180,000 2012 V tuned up, EGR valve/cooler cleaned and about three days later started noticing white smoke. Got the car returned to garage and was told the head gasket was leaking. Head gasket replaced 25 miles later BANG, oil poured out the bottom on the side of the road had it towed back to shop. Engine pulled, used engine put back in. Mechanic said just bad luck.
Interesting discussion here around the EGR coolers and coolant issues. Nice to be able to come here and get some info.

 

Not bad luck. Bad mechanic. You already had a bent rod before the hg change and they did not check it.

Waiting until white smoke started was a bit late in the first place. A rebuilt engine is the best solution for 2010-14 Prius engines.