Blow by causing service hybrid

What were symptoms as it got increasingly worse? Also has the EGR valve been cleaned or replaced ever? That's the biggest problem with these Gen3 cars, which blows head gaskets so addressing/excluding those issues makes the diagnosis way more legit. For the moment I'm suspicious that the force involved to pop off a hose is at play unless the hose is clogged or was improperly attached.

 

300k miles is a LOT!

 

"Check Hybrid light pcv hose blown of of valve cover"???
Maybe that's what they told you, but the PCV valve is under the intake manifold on the Prius.

 

There's a second PCV hose, between valve cover and intake snorkel? There's some big hose there, you need to remove to take off the snorkel; I think it's for PCV.

 

And it’s clamped at both ends. Granted, just a squeeze clamp, but that’s some pressure to blow that off.

 

if you do decide to keep it I'd recommend AAA or another auto club.
I'm considering it at 35k, but I have two other headaches approaching 200k in the stable.

 

Yes, the hose to the valve cover is the pcv breather. It supplies fresh air to the crankcase while the pcv valve draws fumes into the intake manifold.

I couldn't imagine the breather hose getting "blown" off unless it was clogged (??) while there was a ton of blow-by. The engine would be leaking oil from most every seal and gasket if that was the case.

If the ends of the breather hose aren't petrified or split I would secure them with gear clamps & see what happens.

Posted via the PriusChat mobile app.

 

I'm guessing a leak down test and/or compression test would be a great idea. Advance Auto Parts - Down for Maintenance

Wondering about piston rings and how they allow for leakage. There are some posts regarding fuel additives and engine oil additives that owners used in their Prius to break up the carbon deposits on the rings since they can bind in their seats reads like and not seal correct and therefore letting pressure from combustion enter into the crankcase through the leaky space that the rings are supposed to seal between the piston and cylinder wall.

Other leakage can be through the valves and I guess somehow coming backwards to blow out the PCV Valve Ventilation Hose from the direction of going backwards to the PCV Valve from the Intake Manifold.

Guessing the other way around where the pressure is building up from leaky rings on the pistons and going into the crankcase and then PCV Valve into the Ventilation Hose before the intake. Possibly, the intake is clogged really bad at the intake manifold location where the PCV Valve Ventilation Hose attaches as I guess that's the hose coming off.

Might even be the Ventilation Hose is clogged since I recently posted an image and video of the preliminary work I've performed regarding the PCV Valve circuit preventative maintenance (PM) and upgrade... where I was stunned to find chunks of carbon deposited inside the Ventilation Hose just prior to the intake in the larger ~5/8" ID section.

Not certain in any of your scenarios since there really isn't enough information presented to detail a more likely situation.