2015 1.8L rattling at low rpm, head gasket?

Thanks. I always look online for good videos first and I see there are a bunch. I have a gen2 that I currently drive that is problem free, so I am not in a rush to get this done.
I can't see the downside to the catch can. Also seems easy enough to take out of the loop if needed, but I have never had to worry about one before. I think I am going to go with a budget model on Amazon with a bottom drain, to make frequent service easier.

 

I hope you keep us updated… I am sure most of your assumptions are wrong

 

It's from misfires, I'm pretty sure a hydro lock would cause serious damage. So yes, there are many things that can cause a rattle (anything that causes misfires), but if you have misfires on 1 and 2 and it regularly happens on cold starts then the writing is on the wall.

 

Learning so much tonight.

 

It might not be as important as far as effecting drivability, but one might argue that is important for maintaining proper cylinder temps and EGR function, which is why I clean mine every year. The theory of "it clogs quick so don't bother" is pretty wild to me. On the other hand, I barely ever fully clean my valve I just quickly wire-brush the seal. It's pretty much stayed at the same level of slightly carbon coated for the past 4 years. I'm certainly no expert.

 

Not much “H” in that IMHO LOL. The cooler carbon build-up is gradual, but inevitable. It’s a third Gen feature.

I see, oil just “scoots” through the combustion chamber.

Don’t get me started.

 

I can feel the tension in this thread

my only advice is to ask questions and take advice with an open mind and be ready to leave some assumptions behind. The Prius is not a typical car so what you have learned elsewhere may not apply fully

the big contributors on this site are very knowledgeable about these cars and answer questions like engineers and mechanics. I defer to them

 

PCV clogging would do that.

Like Gasket Master for example? Their forte is fixing them, and they have some theories as to why the gaskets blow, but... Keep in mind what keeps them in business.

 

Have you ever done a compression test yet? if so than you realize wihch cylinder is low compress, it should be arround 105 & up other than that YES you are right it's a Headgasket. make sure befor all of that check the spark plug and observe the antifreez tank to see if it's low, if you have access to run a DTC run
1- Sparkplugs
2- Engine waterpump
3- fuel injectros

 

LOL. Everyone here has been perfectly fine. You've received plenty of ideas and you don't seem to keen on listening to them, which is perfectly fair since this is a public forum, but stop pretending like you're "taking flak". I try to appreciate people taking their time to try to help me even if they don't do it exactly how I want them to.

 

Seems to me that an EGR system that is not doing its job correctly can contribute to head gasket failure. How do I know this? ChatGPT.
According to their knowlege base, a clogged EGR will result in ...

1. **Increased Combustion Temperatures**: A clogged EGR system can result in higher combustion temperatures, which can increase the thermal stress on the engine components, including the head gasket.

2. **Engine Knocking**: Higher combustion temperatures can also lead to engine knocking (pre-ignition or detonation), which creates excessive pressure and can damage the head gasket.

3. **Uneven Cylinder Temperatures**: A malfunctioning EGR system can cause uneven temperatures across the cylinders, leading to thermal expansion and contraction that can compromise the integrity of the head gasket.

4. **Increased Engine Load**: A clogged EGR system can cause the engine to work harder to maintain performance, increasing the overall stress on the engine and its components.

To prevent these issues, it's important to maintain the EGR system by cleaning or replacing components as needed. Regular maintenance and addressing any EGR-related issues promptly can help protect the head gasket and other engine components from damage. If you suspect a problem with the EGR system, it's advisable to have it inspected and serviced by a qualified mechanic.

So there you go... Several good reasons why the EGR is important to safeguard your head gasket. Is it the only way for one to fail? Nope. We have an electric water pump that can stop pumping, old age...

Point is that the Prius is a victim of EGR issues and it requires maintenance. Outside of this forum, do people know this? not sure. Does the owner's manual have a maintenance procedure to service it? I checked my car's history ( toyota owner's site, and unless EGR service was bundled in something else, it was not done).

 

And once the head gasket is blown, cleaning the EGR then does not fix the head gasket. In the course of head gasket replacement is a good time to clean it though, wipers and cowl off, coolant drained, intake manifold off, and so on.