Need New Engine in my 2010. Head Gasket. Have many 2012 and newer fell the same fate?

The Prius C has the same startup knock problem. I witnessed my mother-in-law's '16 C do this as I had to repark it. It happened in Florida in 80* weather.

I find that my OCC is half full once a week in the cold weather. My OCC sits in the intake air. I prefer this as I know my intake is staying clean.

Pixel XL ?

 

Pics of your setup?

 

IMG_20170717_122331_mod by mjoo posted Jul 18, 2017 at 1:16 PM

 

Thanks for the visual .

I see this pic is from a couple of months ago.

Have you had any issues with the braided hose pinching or collapsing. The hose has to snake around the throttle body inlet to get over there, and it might be kinking en route.

Just curious.

 

The braided hose that came with the OCC kit is in the landfill. I purchased the braided hose in @danlatu's OCC shopping list. Still going strong with no kinks.

 

How many miles are you doing in that time? That seems like a lot: I saw about 100 cc over 6 winter months, around 3000 kms travelled. Maybe your lower winter temps at play?

Or more efficient catch can? I'm thinking to at least have another look through the throttle body, or maybe lift it off, see what if anything is accumulating.

 

Unless we're on vacation maybe 50-100 miles per week

Pixel XL ?

 

I’m in the 80 miles a day and 400 miles a week club. In that time I’ve gotten about 3 ounces collected from 7 k miles driven.

I check the catch can dispstick every weekend though just in case.

 

I guess I'm not quite following how head gasket failures are related to the PCV system. Usually head gasket failures are a symptom of overheating. When the engine overheats, the top and bottom halves of the engine warp unevenly and then the head gasket can't seal properly. Replacing the head gasket doesn't usually solve the problem as the top and bottom of the engine are still warped and it just fails again. Generally the solution is to machine the top and bottom of the engine flat again and install a new head gasket (sometimes an extra thick one to account for the loss of material and maintain the same compression ratio). Home mechanics will do this with a very flat surface and sandpaper.

Are you saying that the cause of the head gasket failure is from the PCV valve clogging or not working properly, and therefore excessive pressure developing in the crankcase, putting extra stress on the headgasket and therefore failing? I'm not sure if I believe this is really the cause - the headgasket is tested against the full pressure of combustion in the cylinders on each ignition; some additional pressure in the crankcase seems unlikely to cause a problem. To me it sounds like you have two unrelated problems: slight engine block warping and worn piston rings. The general cause of oil usage in the Prius as I've understood it, is from the piston rings wearing and/or getting gunked up with hydrocarbons.

 

Maybe a domino effect? Just speculating: oil vapour is migrating from the crankcase to the intake manifold via the PCV system, burning, and the carbon from that combustion is contributing to clogging of the EGR cooler,valve, pipe and intake manifold passages. And, a properly flowing EGR is instrumental in keeping engine temperatures in normal range.

 

This is possible. The high heat of combustion in the cylinders with uncooled exhaust gases might not show up via high coolant temperature either. But similarly to running an engine lean, there would be very high combustion temps that could certainly heat up and warp the metal around the head gasket. This is a good theory , worth it for the OP to look into.

 

I have a hard time understanding how EGR gases can cool an engine, say compared to ambient air. But this has been stated a few times, by knowledgeable members (who specifically, escapes me), that the engine is actually dependent on properly operating EGR, to keep it's temperature in normal operating range.

My first take would be that EGR is just a necessary evil, to reduce pollution, and the engine can tolerate it. But apparently if you were for example try to defeat the EGR system, block it, engine temps would climb. Maybe someone can explain why.

 

I couldn't help myself, so I looked into this. There are three main reasons that EGR gasses result in lower temperature combustion. Go Science!

1. It reduces the amount of available oxygen in the combustion chamber. This results in a slower, cooler combustion. This is similar to the effect as can be seen when switching from a lean to stochiometric mix. Lean combustion occurs as a fast and hot flame front due to the extra oxygen available. The recirculated exhaust gas has almost no oxygen in it, so instead of burning fuel in 21% O2 air, you could reduce this to 18% O2 air (15% exhaust gas/85% air mixture). This slows down the combustion rate, hence results in lower combustion temperature.
2. Exhaust gas has a greater specific energy than air. Exhaust gas has high amounts of water and CO2 in it. Both of these molecules have higher specific energy than N2 or O2 (the majority of air). What this means is if you add the same amount of energy to the exhaust gas, it will heat up less.

One way of thinking about this is if you take two pans and fill one with water and one with alcohol (same amount in each). You place both on the stove on identical burners and turn them on maximum for exactly two minutes. The temperature rise of the alcohol will be more than the water. This is because alcohol has a lower specific energy than water. In this example, the alcohol is analogous to normal air in combustion chamber and the water analogous to the exhaust.

3. The total mass of air entering the cylinders is increased. As there is more total air in the cylinder, for the same amount of added heat, it warms up less.