Headgasket failure imminent?

Hi all!

2010 Prius with 160K miles on it.

I’ve cleaned the intake manifold and the EGR pipe about two-three weeks ago.

The EGR valve and the cooler: haven’t touched them yet.

The car sat for a couple of days while I was waiting for a side glass replacement.

I’m in Washington state, no cold startup (the lowest reading tonight was 13°C).

Got a quick rattle this morning and three codes (no check engine light yet):
P0300
P0303
P0304

Is this what I think it is: the beginning of the head gasket failure?

No noticeable engine coolant leak yet.

 

BTW, I forgot to mention in the initial post that I performed EGR flow test about a month ago. Got close to normal numbers in Techstream (18-19) despite yet-to-be-cleaned intake manifold and EGR pipe.

The only difference today was that the car sat for 2-3 nights. I usually do lots of short trips.

I’ve driven 100 miles mostly highway since I wrote this post and haven’t heard a single misfire.

I will try to do a radiator pressure test sooner than later - but Amazon keeps delaying my order for CTA Tools 7103 adapter- are there any alternatives that I could buy? Already got the Maddox radiator pressure test kit from HF.

 

Well, I have a privilege of owning both 2010 Prius and 2012 Prius v.

Just did a test with a liquid on 2010 and it doesn’t look good:

2010 Exhaust Leak Test by bkman posted Jul 6, 2024 at 9:58 AM

When the same test was performed on 2012 Prius v, the liquid came the same color.

Probably will do a pressure test just to be sure, but I desperately need an adapter for the tank.

 

I inspected all four cylinders today with the boroscope after the car has been in the garage for the entire night - nothing close to leaking coolant that I can see. Amazon finally shipped the adapter, so hopefully I can do the pressurized coolant test next weekend or so.

I did the cylinder leak test using HF Maddox tester at TDC for every cylinder - found minimal (0.5 PSI) leak on all of them (at 70 PSI). I pulled the oil dipstick and took off the coolant radiator cap but haven't disconnected the PCV valve hose during the test.

Found some the beginnings of cylinder wall damage on #2 and #3 - haven't really grasped what to do next.

 

Had anyone used oil cleaners? AMD mentions them here:

?

While changing the head gasket is on the edge of my abilities (mostly at confidence level: I've cleaned the intake manifold and EGR tube two times and took cowl and spark plugs multiple times without an issue, but that's about it), taking the engine apart (even the simple one as 2ZR-FXE) is the entire different story - as a homeowner I don't have access to a lift, crane and an engine stand. And no desire of getting them for a job or two.

I'm trying to decide what to do best now - just attempt to change the head gasket and run the cleaner in order to dissolve any existing carbon deposits inside oil tension rings or buy the updated pistons and rings and pay a mechanic to rebuild the engine.